Hydrogel composed of potassium acrylate, acrylamide, and mineral as soil conditioner under saline conditions

Hydrogels have potential as soil conditioners due to their high capacity to retain water and mitigate soil salinity. However, investigations under saline conditions are necessary because there are losses in both water absorption and salinity mitigation depending on the composition of hydrogel and ions involved in salinity. In this work, we studied a commercial hydrogel in two experiments. The first experiment was conducted in the laboratory to evaluate the absorption by the hydrogel of water with electrical conductivity (EC) of 0.5, 1.5, 3.0, and 4.5 dS m-1, promoted by NaCl. The second experiment was conducted in a greenhouse in a 2 × 4 factorial scheme (with and without hydrogel × EC of the first experiment). Although salinity reduced water absorption by hydrogel by 84 %, the polymer applied in a sandy soil under saline conditions reduced water losses by 58 %. However, hydrogel did not increase the final soil moisture (~ 0.10 g g-1). The polymer reduced Na+ concentration in leachate from 1,499 to 1,219 mg L-1 at the highest salinity level (4.5 dS m-1), but it increased Na+ soil availability by 0.1 mg kg-1 in comparison with polymer absence. Hydrogel application increased Na+ content in plants from 9 to 13 mg kg-1 at the highest salinity, while K+ content was 10 to 16 mg kg-1 lower than that observed without a polymer. Hydrogel 0.07 % (w/w) reduced maize biomass, indicating damage by monovalent ions, compromising the polymer potential under salinity.

Sensitivity of tuberous roots crops to salinity in a protected environment / Sensibilidade de culturas de raízes tuberosas à salinidade em ambiente protegido

Soil salinity has been a limiting barrier for the production of vegetables in protected environments. Thus, the understanding of the sensitivity of species to this stress factor must be explored, seeking better growing conditions.Under the hypothesis that beet and radish crops are sensitive to variations in soil salinity, even at low levels, the objective of this work was to evaluate the development and productivity of these two species in soils with different salinities in a protected environment. The experimental design was completely randomized and treatments were formed by the soil salinity levels, obtained with the application of saline solution (NaCl in water), considering the soil electrical conductivity of 0.36 dS m-1as low salinity, of 1.05 dS m-1as moderate salinity and 2.43 dS m-1as elevated. For all variables analyzed, except for the relative chlorophyll index in beet plants, it was found that the increase in soil salinity resulted in significant development losses of beet and radish plants. Therefore, we concluded that beet and radish crops are sensitive to the variation in soil salinity, even in relatively low concentrations, making these species an unattractive choice for cultivation in systems that present this problem.(AU)

A salinidade dos solos tem sido uma barreira limitadora para a produção de hortaliças em ambientes protegidos. Assim, o entendimento quanto a sensibilidade das espécies a esse fator de estresse deve ser explorado, buscando melhores condições de cultivo. Sob a hipótese de que as culturas de beterraba e rabanete são sensíveis às variações da salinidade do solo, mesmo em níveis baixos, o objetivo deste trabalho foi avaliar o desenvolvimento e a produtividade dessas duas espécies em solos comdiferentes salinidades em ambiente protegido. O delineamento experimental foi inteiramente casualizado e os tratamentos foram formados pelos níveis de salinidade do solo, obtidos com a aplicação de solução salina (NaCl em água), considerando a condutividade elétrica do solo de 0,36 dS m-1como baixa salinidade, de 1,05 dS m-1como salinidade moderada e 2,43 dS m-1como elevada. Para todas as variáveis analisadas, com exceção do índice relativo de clorofila em plantas de beterraba, verificou-se que o aumento da salinidade do solo resultou em perdas significativas de desenvolvimento de plantas de beterraba e rabanete. Assim, concluímos que as culturas de beterraba e rabanete são sensíveis à variação da salinidade do solo, mesmo em concentrações relativamente baixas, tornando essas espécies uma escolha pouco atrativa para cultivo em sistemas que apresentam este problema.(AU)

Growing broccoli under salinity: the influence of cultivar and season on glucosinolates content

The evaluation of factors that affect glucosinolates (GLS) concentrations in the roots, leaves, and inflorescence of broccoli plants is important in the improvement of the concentration of bioactive compounds and thus in the enhancement of the nutritional properties. In this work, the yield and the concentration of GLS of seven broccoli cultivars (Brassica oleracea var. italica) grown under salinity in field conditions were studied during three different seasons (autumn, winter, and spring). The results show that, generally, salinity did not alter significantly the inflorescence yield during any of the seasons, indicating a high tolerance of the cultivars tested. Yield was reduced only in cultivar Gea in autumn and in cultivar Parthenon in spring. The distribution of the GLS showed that their accumulation was greater in inflorescences and leaves, with higher concentrations in autumn and spring. The activation of GLS synthesis by salinity was restricted to several cultivars and depended on the season, with no reductions compared to control plants. In this study, we discuss the appearance of a Cinnamoyl-indol-GLS derivative in some of the cultivars and seasons with higher incidence in NaCl-treated plants.

Growing broccoli under salinity: the influence of cultivar and season on glucosinolates content

The evaluation of factors that affect glucosinolates (GLS) concentrations in the roots, leaves, and inflorescence of broccoli plants is important in the improvement of the concentration of bioactive compounds and thus in the enhancement of the nutritional properties. In this work, the yield and the concentration of GLS of seven broccoli cultivars (Brassica oleracea var. italica) grown under salinity in field conditions were studied during three different seasons (autumn, winter, and spring). The results show that, generally, salinity did not alter significantly the inflorescence yield during any of the seasons, indicating a high tolerance of the cultivars tested. Yield was reduced only in cultivar Gea in autumn and in cultivar Parthenon in spring. The distribution of the GLS showed that their accumulation was greater in inflorescences and leaves, with higher concentrations in autumn and spring. The activation of GLS synthesis by salinity was restricted to several cultivars and depended on the season, with no reductions compared to control plants. In this study, we discuss the appearance of a Cinnamoyl-indol-GLS derivative in some of the cultivars and seasons with higher incidence in NaCl-treated plants.(AU)

Herbaceous biomass yield in the saline soils during the dry and rainy seasons in the municipality of Pentecoste, CE, Brazil / Rendimento da biomassa herbácea em solos salinos nas estações seca e chuvosa no município de Pentecoste, CE, Brasil

This study was an endeavor undertaken to assess the biomass yield of the species that are native to a particular region characterized by saline soil, in the Irrigated Perimeter Curu-Pentecoste, in the municipality of Pentecoste-CE, corresponding to the qualities of moisture, pH and electrical conductivity (EC) of the soil. The experiment was conducted in six areas, with area 1, the one nearest to the collecting drain, the end having the highest salinity and area 6, the one furthest away from the collecting drain, the end with the lowest salinity. The factorial design with the 2 x 6 scheme was adopted, in which the first and second factors referred, respectively, to the seasons (drought and rain collection) and collection areas. In each area, eight permanent 5 x 5 m plots were demarcated, which included 8 repetitions per treatment. Within each permanent plot the quantity of forage was gathered within an area of 0.25 x 0.25 m. Soil samples were taken from a depth of 0-20 cm, and the EC, pH and soil moisture were determined. The phytomass was oven dried, after which the water content and yield were recorded. Three subsamples per area were burned in a muffle furnace to determine the percentage of ash content. The resultant high pH and EC values, typical of arid soils and related to the significantly low humidity, can cause harm to most of the crops cultivated in the Northeast of Brazil. However, the biomass yield was substantial, indicating that the species occurring there possessed adaptive mechanisms to enable them to tolerate the conditions of saline soil and water stresses prevalent there.(AU)

O objetivo do trabalho foi avaliar o rendimento de biomassa vegetal de espécies presentes naturalmente em uma área com o solo salinizado no perímetro irrigado Curu-Pentecoste, no município de Pentecoste, CE, correlacionando com os atributos umidade, pH e condutividade elétrica (CE) do solo. O experimento foi realizado em 6 áreas, sendo a área 1 mais próxima do dreno coletor o extremo mais salinizado, e a área 6 mais distante do dreno coletor, o extremo menos salinizado. Utilizamos do delineamento fatorial no esquema 2 x 6, com primeiro fator referente às estações de coleta (seca e chuva), e o segundo relativo às áreas. Foram marcadas em cada uma das áreas 8 parcelas permanentes de 5 x 5m e em cada parcela permanente foram realizadas coletas da porção forrageira dentro de um quadrado de 0,25 x 0,25 m. Amostras de solo de 0-20 cm de profundidade foram coletadas para a obtenção da CE, do pH e da umidade do solo. A fitomassa foi secada em estufa, onde foram mensurados o seu conteúdo de água e biomassa seca. Três subamostras por área foram queimadas em mufla para a obtenção do seu conteúdo de cinzas. O pH e CE elevados do solo mostraram características típicas de solos de clima árido, que associados a uma significante diminuição da umidade desse, podem causar prejuízos na maioria dos cultivos no Nordeste brasileiro. Entretanto, o rendimento de biomassa foi elevado, o que demonstra que as espécies ali presentes possuem mecanismos adaptativos para tolerância aos estresses salino e hídrico.(AU)

Aplicação foliar de prolina no crescimento e fisiologia do milho verde cultivado em solo salinizado / Proline of leaf application on growth and physiology of green corn on soil salinity different levels

O milho (Zea mays L.) é uma das culturas mais cultivadas no mundo. No Brasil, este cereal tem ampla diversidade de uso. A maioria das áreas onde há produção de milho, utiliza-se a irrigação, entretanto, quando realizada de forma inadequada, torna-se preponderante para a salinização dos solos. Assim, objetivou-se avaliar, o efeito da aplicação foliar de prolina no crescimento e fisiologia da cultura do milho cultivado em solo salinizado. O experimento foi conduzido no Centro de Ciência e Tecnologia Agroalimentar (CCTA), pertencente à Universidade Federal de Campina Grande (UFCG), Pombal, PB, no período de março a abril de 2015, utilizando-se a variedade de milho AG 1051. Os tratamentos foram constituídos por dois níveis de salinidade do solo, (CE= 3,26 e 0,86 dS/m) e cinco concentrações de prolina (0; 2,5; 5,0; 7,5 e 10 mmol L-¹) aplicada via foliar nas plantas de milho. O delineamento experimental foi inteiramente casualizado, no esquema fatorial 2 x 5, com quatro repetições. Foi observado um maior crescimento e acúmulo de massa quando as plantas foram conduzidas em solo de menor salinidade (CE= 0,86 dS/m).  A transpiração foi influenciada pela salinidade e pela concentração de prolina. A maior taxa de concentração intercelular de CO2 (Ci) foi obtida na concentração de 7,5 mmol L-¹ prolina. As concentrações de prolina não influenciaram nos aspectos de...

Corn (Zea mays L.) is one of the most cultivated crops in the world. In Brazil, this cereal has a wide diversity of use. Most of the areas where maize production is used is irrigation, however, when performed inadequately it becomes preponderant for salinization of soils. The effect of proline foliar application on the growth and physiology of the green maize cultivated in salinized soil was evaluated. The experiment was conducted at the Center for Agro-Food Science and Technology (CCTA), belonging to the Federal University of Campina Grande (UFCG), Pombal, PB, from March  to April 2015, using maize variety AG 1051. The treatments consisted of two levels of soil salinity (EC = 3.26 and 0.86 dS/m) and five concentrations of proline (0, 2.5, 5.0, 7.5 and 10 mmol L -¹) applied by leaf on corn plants. The experimental design was completely randomized, in the 2 x 5 factorial scheme, with four replications. A higher growth and mass accumulation was observed when the plants were conducted in soil of lower salinity (CE = 0.86 dS/m). Transpiration was influenced by salinity and proline concentration. The highest rate of intercellular CO2 concentration (Ci) was obtained at the concentration of 7.5 mmol L-¹ proline. Proline concentrations did not influence the growth and mass accumulation aspects of maize.

Aplicação foliar de prolina no crescimento e fisiologia do milho verde cultivado em solo salinizado / Proline of leaf application on growth and physiology of green corn on soil salinity different levels

O milho (Zea mays L.) é uma das culturas mais cultivadas no mundo. No Brasil, este cereal tem ampla diversidade de uso. A maioria das áreas onde há produção de milho, utiliza-se a irrigação, entretanto, quando realizada de forma inadequada, torna-se preponderante para a salinização dos solos. Assim, objetivou-se avaliar, o efeito da aplicação foliar de prolina no crescimento e fisiologia da cultura do milho cultivado em solo salinizado. O experimento foi conduzido no Centro de Ciência e Tecnologia Agroalimentar (CCTA), pertencente à Universidade Federal de Campina Grande (UFCG), Pombal, PB, no período de março a abril de 2015, utilizando-se a variedade de milho AG 1051. Os tratamentos foram constituídos por dois níveis de salinidade do solo, (CE= 3,26 e 0,86 dS/m) e cinco concentrações de prolina (0; 2,5; 5,0; 7,5 e 10 mmol L-¹) aplicada via foliar nas plantas de milho. O delineamento experimental foi inteiramente casualizado, no esquema fatorial 2 x 5, com quatro repetições. Foi observado um maior crescimento e acúmulo de massa quando as plantas foram conduzidas em solo de menor salinidade (CE= 0,86 dS/m).  A transpiração foi influenciada pela salinidade e pela concentração de prolina. A maior taxa de concentração intercelular de CO2 (Ci) foi obtida na concentração de 7,5 mmol L-¹ prolina. As concentrações de prolina não influenciaram nos aspectos de...(AU)

Corn (Zea mays L.) is one of the most cultivated crops in the world. In Brazil, this cereal has a wide diversity of use. Most of the areas where maize production is used is irrigation, however, when performed inadequately it becomes preponderant for salinization of soils. The effect of proline foliar application on the growth and physiology of the green maize cultivated in salinized soil was evaluated. The experiment was conducted at the Center for Agro-Food Science and Technology (CCTA), belonging to the Federal University of Campina Grande (UFCG), Pombal, PB, from March  to April 2015, using maize variety AG 1051. The treatments consisted of two levels of soil salinity (EC = 3.26 and 0.86 dS/m) and five concentrations of proline (0, 2.5, 5.0, 7.5 and 10 mmol L -¹) applied by leaf on corn plants. The experimental design was completely randomized, in the 2 x 5 factorial scheme, with four replications. A higher growth and mass accumulation was observed when the plants were conducted in soil of lower salinity (CE = 0.86 dS/m). Transpiration was influenced by salinity and proline concentration. The highest rate of intercellular CO2 concentration (Ci) was obtained at the concentration of 7.5 mmol L-¹ proline. Proline concentrations did not influence the growth and mass accumulation aspects of maize.(AU)

Variedades de feijão-fava submetidas à níveis de salinidade e adubação orgânica / Varieties of bean-fava submitted to levels of salinity and organic fertilizing

As altas temperaturas e baixa pluviosidade salinizam água e solo na Região Nordeste, ocasionando redução no desenvolvimento de diversas espécies, dentre elas, o feijoeiro fava.Para tanto, objetivou-se avaliar variedades de feijão-fava submetidas a níveis de salinidade e adubação orgânica. O estudo foi conduzido em ambiente protegido, nas dependências da Universidade Federal de Campina Grande, campus Pombal. O delineamento experimental foi em blocos ao acaso, disposto em esquema fatorial 3x4x5, sendo: três variedades de feijão-fava (V1: lavandeira; V2: raio-de-sol e V3: rajada), quatro volumes de esterco bovino (A1: 0% - sem adubação; A2: 8%; A3: 16% e A4: 24%), aplicados em função do volume de solo do recipiente e cinco níveis de salinidade na água de irrigação (S1= 0,3 dSm-1; S2= 1,0 dSm-1; S3= 1,7 dSm-1; S4= 2,4 dSm-1e S5= 3,1 dSm-1). A variedade Raio de Sol apresentou maior crescimento em relação às demais, entretanto a cultivar Rajada apresentou maior aclimatização às condições salinas, principalmente com uso do esterco bovino na concentração de 24%. O esterco bovino atenua o efeito nocivo da salinidade, entretanto doses acima de 16% de esterco em altas salinidades podem ser prejudiciais ao feijoeiro-fava.

The high temperatures and low rainfall salinize water and soil in the Northeast Region, causing a reduction in the development of several species, among them, fava bean. The objective of this study was to evaluate bean-fava varieties submitted to levels of salinity and organic fertilization. The study was conducted in a protected environment, in the dependencies of the Federal University of Campina Grande, Pombal campus. The experimental design was a randomized block design, arranged in a 3x4x5 factorial scheme: three varieties of bean (V1: lavandeira, V2: sunshine and V3: rajada), four volumes of bovine manure (A1: 0% - without fertilization; A2: 8%; A3: 16% and A4: 24%), applied as a function of the soil volume of the container and five levels of salinity in the irrigation water (S1 = 0.3 dSm-1; S2 = 1.0 dSm-1; S3 = 1.7 dSm-1; S4 = 2.4 dSm-1 and S5 = 3.1 dSm-1). The Raio de Sol variety presented higher growth in relation to the others, however, the cultivar Rajada presented a higher acclimatization to saline conditions, mainly with the use of bovine manure in the concentration of 24%. Bovine manure attenuates the harmful effect of salinity, however, doses above 16% of manure at high salinity can be harmful to common bean.

Variedades de feijão-fava submetidas à níveis de salinidade e adubação orgânica / Varieties of bean-fava submitted to levels of salinity and organic fertilizing

As altas temperaturas e baixa pluviosidade salinizam água e solo na Região Nordeste, ocasionando redução no desenvolvimento de diversas espécies, dentre elas, o feijoeiro fava.Para tanto, objetivou-se avaliar variedades de feijão-fava submetidas a níveis de salinidade e adubação orgânica. O estudo foi conduzido em ambiente protegido, nas dependências da Universidade Federal de Campina Grande, campus Pombal. O delineamento experimental foi em blocos ao acaso, disposto em esquema fatorial 3x4x5, sendo: três variedades de feijão-fava (V1: lavandeira; V2: raio-de-sol e V3: rajada), quatro volumes de esterco bovino (A1: 0% - sem adubação; A2: 8%; A3: 16% e A4: 24%), aplicados em função do volume de solo do recipiente e cinco níveis de salinidade na água de irrigação (S1= 0,3 dSm-1; S2= 1,0 dSm-1; S3= 1,7 dSm-1; S4= 2,4 dSm-1e S5= 3,1 dSm-1). A variedade Raio de Sol apresentou maior crescimento em relação às demais, entretanto a cultivar Rajada apresentou maior aclimatização às condições salinas, principalmente com uso do esterco bovino na concentração de 24%. O esterco bovino atenua o efeito nocivo da salinidade, entretanto doses acima de 16% de esterco em altas salinidades podem ser prejudiciais ao feijoeiro-fava.(AU)

The high temperatures and low rainfall salinize water and soil in the Northeast Region, causing a reduction in the development of several species, among them, fava bean. The objective of this study was to evaluate bean-fava varieties submitted to levels of salinity and organic fertilization. The study was conducted in a protected environment, in the dependencies of the Federal University of Campina Grande, Pombal campus. The experimental design was a randomized block design, arranged in a 3x4x5 factorial scheme: three varieties of bean (V1: lavandeira, V2: sunshine and V3: rajada), four volumes of bovine manure (A1: 0% - without fertilization; A2: 8%; A3: 16% and A4: 24%), applied as a function of the soil volume of the container and five levels of salinity in the irrigation water (S1 = 0.3 dSm-1; S2 = 1.0 dSm-1; S3 = 1.7 dSm-1; S4 = 2.4 dSm-1 and S5 = 3.1 dSm-1). The Raio de Sol variety presented higher growth in relation to the others, however, the cultivar Rajada presented a higher acclimatization to saline conditions, mainly with the use of bovine manure in the concentration of 24%. Bovine manure attenuates the harmful effect of salinity, however, doses above 16% of manure at high salinity can be harmful to common bean.(AU)

Seed priming improves the germination and growth rate of melon seedlings under saline stress / Condicionamento de sementes melhora a germinação e a taxa de crescimento das plântulas de melão sob estresse salino

The germination and growth of melon (Cucumis melo L.) plants can be severely affected by excess salts in the soil or irrigation water; however, negative effects of salt stress can be attenuated using appropriate methods of seed priming. Thus, effects of osmopriming as inducer of salt stress tolerance in melon seeds exposed to salinity levels were investigated in this study. Seeds were soaked for 22 h at 25 °C in the dark in distilled water (hydropriming) or 0.5% KNO3 solution (osmopriming), and after drying, were distributed in plastic boxes with blotter paper containing different NaCl solutions prepared with osmotic pressure of 0.0 MPa (control), -0.3 MPa (mild stress), and -0.6 MPa (severe stress). Unprimed dry seeds were taken as control. The plastic boxes were kept into a seed germinator, at 25 °C for 14 days. A completely randomized design in a 3 × 3 factorial schemes with four replicates of 25 seeds was used. Results showed that the seed priming with water and KNO3 may be successfully applied on melon seeds to alleviate the adverse effects of saline stress in initial stages of plant growth. However, under severe salt stress conditions, hydropriming should be used because it results in higher germination and initial growth rate of the seedlings when compared to the osmopriming. Use of unprimed seeds should not be adopted in cultivation areas affected by salinity because they result in low germination rate and reduced initial plant growth.(AU)

A germinação e o crescimento de plantas de melão (Cucumis melo L.) podem ser severamente afetadas pelo excesso de sais no solo ou na água de irrigação. No entanto, os efeitos negativos do estresse salino podem ser amenizados com o uso de métodos adequados de condicionamento das sementes. Assim, este estudo objetivou investigar os efeitos do osmocondicionamento como indutor da tolerância ao estresse salino em sementes de melão expostas à níveis de salinidade. As sementes foram imersas por 22 h à 25 °C em água destilada (hidrocondicionamento) ou em solução de 0,5% de KNO3 (osmocondicionamento). Após secagem, as sementes foram distribuídas em caixas plásticas com papel mata-borrão contendo as diferentes soluções de NaCl preparadas com potencial osmótico de 0,0 MPa (controle), -0,3 MPa (estresse suave) e -0,6 MPa (estresse severo). Um tratamento com sementes secas não condicionadas foi utilizado como controle. As caixas plásticas foram mantidas em germinador de sementes, a 25 °C por 14 dias. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 3 × 3, com quatro repetições de 25 sementes. Os resultados mostraram que o condicionamento de sementes com água e KNO3 pode ser aplicado com sucesso em sementes de melão para amenizar os efeitos adversos do estresse salino durante o estágio inicial de crescimento das plantas. No entanto, sob estresse salino severo, o hidrocondicionamento deve ser utilizado por resultar em maior percentagem de germinação e maior taxa de crescimento inicial das plântulas quando comparado ao osmocondicionamento. O uso de sementes de melão sem condicionamento prévio não deve ser adotado em áreas de cultivo afetadas pela salinidade, pois resultam em baixa taxa de germinação e reduzido crescimento inicial das plantas.(AU)

Salinidade do solo em ambiente protegido / Soil salinity in protected environment

Por muito tempo, a exploração dos sistemas agrícolas em sua totalidade vem associado ao manejo inadequado dos agroecossistemas. Um dos problemas que afetam o processo de produção agrícola é a salinização do solo, pois elevados níveis de salinidade dificultam a absorção de água e nutrientes pelos vegetais convertendo-se em problemas de ordem nutricional, toxicológico, físico, químico, biológico e, em casos mais extremos, a salinidade do solo pode desencadear outro processo conhecido como desertificação, tornando o solo inapropriado para o cultivo. No ambiente protegido, o principal meio de adubação é a fertirrigação, cujas causas da salinidade são evidenciadas pelo uso excessivo de fertilizantes e pela má qualidade da água de irrigação que provém em sua maioria de poços com alto teor de cloreto de sódio (NaCl). Diferentemente do que ocorre em cultivos a campo, que há entrada de água, por meio da precipitação natural, a água que entra no ambiente protegido provém unicamente da irrigação, precipitação artificial, onde o método da irrigação localizada é utilizado pela maioria dos produtores. A salinização em ambiente protegido é independente das condições climáticas ou do tipo de solo empregado no cultivo, uma vez que ocorre um aumento da condutividade elétrica da solução do solo aliada a altas doses de adubos que proporcionam o acúmulo de sais na superfície. O presente trabalho teve como objetivo abordar por meio de uma revisão de literatura, os principais fatores que promovem o processo de salinização do solo em ambiente protegido.(AU)

For a long time, the exploration of agricultural systems in their entirety comes associated with the inadequate management of agroecosystems. One of the problems that affect the process of agricultural production is the soil salinization, because high levels of salinity hinder the water and nutrients absorption by vegetables, becoming nutritional, toxicological, physical, chemical, biological problems and in more extreme cases, soil salinity can trigger another process known as desertification, making the soil unsuitable for cultivation. In the protected environment the main means of fertilization is the fertigation, whose salinity causes are evidenced by the excessive use of fertilizers and by the poor quality of irrigation water that comes mostly from wells with high sodium chloride (NaCl) content. Contrary to what happens in field crops, where there is input of water through natural precipitation, water entering the protected environment comes solely from irrigation, artificial precipitation, where the irrigation method is located and used by most producers. The salinization in protected environment is independent of the climatic conditions or the type of soil used in the cultivation, once there is an increase in the electrical conductivity of the soil solution with high doses of fertilizers that provide the accumulation of salts on the surface. The present study had as objective to approach through a literature review, the main factors that promote the process of soil salinization in a protected environment.(AU)

Aplicação de silício no solo: efeito na expressão enzimática de sementes oriundas de plantas de arroz sob estresse salino / Application of silicon to the soil: effect on enzymatic expression in rice seed produced under salt stress

A utilização de silício pode acarretar em aumento da capacidade biológica da planta em resistir às condições adversas do meio ambiente. Diante disso, o presente trabalho teve por objetivo avaliar a expressão isoenzimática de sementes oriundas de plantas cultivadas com aplicação de cinza da casca de arroz, via solo, sob estresse salino. O delineamento utilizado foi em blocos casualizados, em esquema fatorial A x B (Fator A- Cinco doses de cinza da casca de arroz aplicada via solo: 0; 500; 1000; 1500 e 2000 kg ha-¹; Fator B- Três concentrações salinas: 0, 4 e 8 mM), com quatro repetições. Foram realizados os testes de primeira contagem de germinação e germinação, e expressão dos sistemas isoenzimáticos glutamato oxaloacetato transaminase, álcool desidrogenase, glutamato desidrogenase e sorbitol. Variações nos quatro sistemas eletroforéticos analisados podem estar associados ao estresse salino causado durante o crescimento e desenvolvimento de plantas de arroz. O sistema isoenzimático glutamato oxaloacetato transaminase é uma ferramenta complementar à avaliação do potencial fisiológico de sementes de arroz.

The silicon utilization may result in the increased biological ability of the plants to withstand the harsh conditions of the environment. In this sense, the study aimed to evaluate the effect of the application of rice husk ash to the soil in rice plants under salt stress on isoenzymes expression. The experimental design was a randomized block in factorial A x B (Factor A- Five doses of rice husk ash applied to soil: 0.0, 500, 1000, 1500, and 2000 kg ha-¹, Factor B- Three salt concentrations: 0, 4, and 8 mM), with four replications. Tests were the first count of germination and germination, and expression of isozyme systems glutamate oxaloacetate transaminase, alcohol dehydrogenase, glutamate dehydrogenase, and sorbitol. Variations in the all analyzed electrophoretic systems may be associated with salt stress caused during the growth and development of rice plants. The isoenzyme system glutamate oxaloacetate transaminase is a complementary tool to assess the physiological rice seed quality.

Aplicação de silício no solo: efeito na expressão enzimática de sementes oriundas de plantas de arroz sob estresse salino / Application of silicon to the soil: effect on enzymatic expression in rice seed produced under salt stress

A utilização de silício pode acarretar em aumento da capacidade biológica da planta em resistir às condições adversas do meio ambiente. Diante disso, o presente trabalho teve por objetivo avaliar a expressão isoenzimática de sementes oriundas de plantas cultivadas com aplicação de cinza da casca de arroz, via solo, sob estresse salino. O delineamento utilizado foi em blocos casualizados, em esquema fatorial A x B (Fator A- Cinco doses de cinza da casca de arroz aplicada via solo: 0; 500; 1000; 1500 e 2000 kg ha-¹; Fator B- Três concentrações salinas: 0, 4 e 8 mM), com quatro repetições. Foram realizados os testes de primeira contagem de germinação e germinação, e expressão dos sistemas isoenzimáticos glutamato oxaloacetato transaminase, álcool desidrogenase, glutamato desidrogenase e sorbitol. Variações nos quatro sistemas eletroforéticos analisados podem estar associados ao estresse salino causado durante o crescimento e desenvolvimento de plantas de arroz. O sistema isoenzimático glutamato oxaloacetato transaminase é uma ferramenta complementar à avaliação do potencial fisiológico de sementes de arroz.(AU)

The silicon utilization may result in the increased biological ability of the plants to withstand the harsh conditions of the environment. In this sense, the study aimed to evaluate the effect of the application of rice husk ash to the soil in rice plants under salt stress on isoenzymes expression. The experimental design was a randomized block in factorial A x B (Factor A- Five doses of rice husk ash applied to soil: 0.0, 500, 1000, 1500, and 2000 kg ha-¹, Factor B- Three salt concentrations: 0, 4, and 8 mM), with four replications. Tests were the first count of germination and germination, and expression of isozyme systems glutamate oxaloacetate transaminase, alcohol dehydrogenase, glutamate dehydrogenase, and sorbitol. Variations in the all analyzed electrophoretic systems may be associated with salt stress caused during the growth and development of rice plants. The isoenzyme system glutamate oxaloacetate transaminase is a complementary tool to assess the physiological rice seed quality.(AU)

Antioxidant response of cowpea co-inoculated with plant growth-promoting bacteria under salt stress

Soil salinity is an important abiotic stress worldwide, and salt-induced oxidative stress can have detrimental effects on the biological nitrogen fixation. We hypothesized that co-inoculation of cowpea plants with Bradyrhizobium and plant growth-promoting bacteria would minimize the deleterious effects of salt stress via the induction of enzymatic and non-enzymatic antioxidative protection. To test our hypothesis, cowpea seeds were inoculated with Bradyrhizobium or co-inoculated with Bradyrhizobium and plant growth-promoting bacteria and then submitted to salt stress. Afterward, the cowpea nodules were collected, and the levels of hydrogen peroxide; lipid peroxidation; total, reduced and oxidized forms of ascorbate and glutathione; and superoxide dismutase, catalase and phenol peroxidase activities were evaluated. The sodium and potassium ion concentrations were measured in shoot samples. Cowpea plants did not present significant differences in sodium and potassium levels when grown under non-saline conditions, but sodium content was strongly increased under salt stress conditions. Under non-saline and salt stress conditions, plants co-inoculated with Bradyrhizobium and Actinomadura or co-inoculated with Bradyrhizobium and Paenibacillus graminis showed lower hydrogen peroxide content in their nodules, whereas lipid peroxidation was increased by 31% in plants that were subjected to salt stress. Furthermore, cowpea nodules co-inoculated with Bradyrhizobium and plant growth-promoting bacteria and exposed to salt stress displayed significant alterations in the total, reduced and oxidized forms of ascorbate and glutathione. Inoculation with Bradyrhizobium and plant growth-promoting bacteria induced increased superoxide dismutase, catalase and phenol peroxidase activities in the nodules of cowpea plants exposed to salt stress. The catalase activity in plants co-inoculated with Bradyrhizobium and Streptomyces was 55% greater than in plants...(AU)

QTLs for seedling traits under salinity stress in hexaploid wheat / Caracterização de QTLs por traços de sementes sob o estresse de salinidade em trigo Hexaploid

Soil salinity limits agricultural production and is a major obstacle for increasing crop yield. Common wheat is one of the most important crops with allohexaploid characteristic and a highly complex genome. QTL mapping is a useful way to identify genes for quantitative traits such as salinity tolerance in hexaploid wheat. In the present study, a hydroponic trial was carried out to identify quantitative trait loci (QTLs) associated with salinity tolerance of wheat under 150mM NaCl concentration using a recombinant inbred line population (Xiaoyan 54×Jing 411). Values of wheat seedling traits including maximum root length (MRL), root dry weight (RDW), shoot dry weight (SDW), total dry weight (TDW) and the ratio of TDW of wheat plants between salt stress and control (TDWR) were evaluated or calculated. A total of 19QTLs for five traits were detected through composite interval mapping method by using QTL Cartographer version 2.5 under normal and salt stress conditions. These QTLs distributed on 12 chromosomes explained the percentage of phenotypic variation by individual QTL varying from 7.9% to 19.0%. Among them, 11 and six QTLs were detected under normal and salt stress conditions, respectively and two QTLs were detected for TDWR. Some salt tolerance related loci may be pleiotropic. Chromosome 1A, 3A and 7A may harbor crucial candidate genes associated with wheat salt tolerance. Our results would be helpful for the marker assisted selection to breed wheat varieties with improved salt tolerance.(AU)

A salinidade do solo limita a produção agrícola. O trigo mole é uma das culturas mais importantes com característica allohexaploid e genoma altamente complexo. O mapeamento QTL é uma maneira muito útil de identificar genes para traços quantitativos, como a tolerância à salinidade em trigo hexaplóide. No presente estudo realizou-se um ensaio hidropónico para identificar locos de traços quantitativos (QTLs) associados à tolerância à salinidade do trigo sob concentração de NaCl 150 mM, usando uma população de linhagem consanguíneo recombinante (Xiaoyan 54 × Jing 411). Os valores dos traços de mudas de trigo, incluindo comprimento máximo da raiz (MRL), peso seco da raiz (RDW), ponha o peso seco (SDW), peso seco total (TDW) e a proporção das plantas de trigo TDW entre o estresse salgado e o controle (TDWR), foram avaliados ou calculados. Um total de 19QTLs para cinco traços foram detectados através do método de mapeamento de intervalo composto usando a versão 2.5 do cartógrafo QTL sob condições normais e de estresse salino. Estes QTLs distribuídos em 12 cromossomos explicaram a porcentagem de variação fenotípica por QTL individual variando de 7,9% a 19,0%. Entre eles, foram detectados 11 e 6 QTLs em condições de estresse normal e sal, respectivamente, e dois QTLs foram detectados para TDWR. Cromossoma 1A, 3A e 7A podem conter genes que são candidatos cruciais associados à tolerância ao sal de trigo. Nossos resultados seriam úteis para a seleção assistida por marcadores para produzir variedades de trigo com tolerância salina melhorada.(AU)

QTLs for seedling traits under salinity stress in hexaploid wheat / Caracterização de QTLs por traços de sementes sob o estresse de salinidade em trigo Hexaploid

Soil salinity limits agricultural production and is a major obstacle for increasing crop yield. Common wheat is one of the most important crops with allohexaploid characteristic and a highly complex genome. QTL mapping is a useful way to identify genes for quantitative traits such as salinity tolerance in hexaploid wheat. In the present study, a hydroponic trial was carried out to identify quantitative trait loci (QTLs) associated with salinity tolerance of wheat under 150mM NaCl concentration using a recombinant inbred line population (Xiaoyan 54×Jing 411). Values of wheat seedling traits including maximum root length (MRL), root dry weight (RDW), shoot dry weight (SDW), total dry weight (TDW) and the ratio of TDW of wheat plants between salt stress and control (TDWR) were evaluated or calculated. A total of 19QTLs for five traits were detected through composite interval mapping method by using QTL Cartographer version 2.5 under normal and salt stress conditions. These QTLs distributed on 12 chromosomes explained the percentage of phenotypic variation by individual QTL varying from 7.9% to 19.0%. Among them, 11 and six QTLs were detected under normal and salt stress conditions, respectively and two QTLs were detected for TDWR. Some salt tolerance related loci may be pleiotropic. Chromosome 1A, 3A and 7A may harbor crucial candidate genes associated with wheat salt tolerance. Our results would be helpful for the marker assisted selection to breed wheat varieties with improved salt tolerance.

A salinidade do solo limita a produção agrícola. O trigo mole é uma das culturas mais importantes com característica allohexaploid e genoma altamente complexo. O mapeamento QTL é uma maneira muito útil de identificar genes para traços quantitativos, como a tolerância à salinidade em trigo hexaplóide. No presente estudo realizou-se um ensaio hidropónico para identificar locos de traços quantitativos (QTLs) associados à tolerância à salinidade do trigo sob concentração de NaCl 150 mM, usando uma população de linhagem consanguíneo recombinante (Xiaoyan 54 × Jing 411). Os valores dos traços de mudas de trigo, incluindo comprimento máximo da raiz (MRL), peso seco da raiz (RDW), ponha o peso seco (SDW), peso seco total (TDW) e a proporção das plantas de trigo TDW entre o estresse salgado e o controle (TDWR), foram avaliados ou calculados. Um total de 19QTLs para cinco traços foram detectados através do método de mapeamento de intervalo composto usando a versão 2.5 do cartógrafo QTL sob condições normais e de estresse salino. Estes QTLs distribuídos em 12 cromossomos explicaram a porcentagem de variação fenotípica por QTL individual variando de 7,9% a 19,0%. Entre eles, foram detectados 11 e 6 QTLs em condições de estresse normal e sal, respectivamente, e dois QTLs foram detectados para TDWR. Cromossoma 1A, 3A e 7A podem conter genes que são candidatos cruciais associados à tolerância ao sal de trigo. Nossos resultados seriam úteis para a seleção assistida por marcadores para produzir variedades de trigo com tolerância salina melhorada.

Gas exchange of citrus rootstocks in response to intensity and duration of saline stress / Trocas gasosas de porta-enxertos de citros em resposta a intensidade e duração do estresse salino

Soil and water salinity cause physiological disorders in sensitive plants, such as altered gas exchange in citrus genotypes. However, it is possible to analyse these effects and to identify genotypes tolerant to salt stress. An experiment was carried out in order to evaluate the tolerance of citrus genotypes considering the irrigation with saline water during rootstock formation. The study took place under greenhouse conditions in Pombal county, Paraiba, Brazil. A randomised block design was used, with treatments arranged in a factorial scheme (5 x 8). The two factors were: [i] five salinity levels of irrigation water (0.8, 1.6, 2.4, 3.2 and 4.0 dS m-1) and [ii] eight genotypes of citrus rootstocks: 1. Rangpur Santa Cruz lime (LCRSTC); 2. common Sunki mandarin (TSKC) x Swingle citrumelo (CTSW) - 028; 3. TSKC x CTSW - 033; 4. TSKC x CTSW - 041; 5. Volkamer lemon (LVK) x Rangpur lime (LCR) - 038; 6. Sunki of Florida mandarin (TSKFL); 7. TSKC and 8. Florida rough lemon (LRF). Gas exchange was evaluated at 15, 30 and 60 days after the beginning of the saline water application. High water salinity reduces gas exchange in citrus genotypes, which was more evident at 15 days from the beginning of stress. The genotypes Santa Cruz Rangpur lime, TSKC x CTSW - 041, LVK x LCR - 038 and Florida rough lemon exhibit a satisfactory physiological behaviour during the first 30 days ofexposure to the stress, showing moderate tolerance to salt stress. The genotypes TSKC x CTSW 033 and common ‘Sunki mandarin are the most sensitive to salinity.(AU)

A salinidade do solo e da água ocasionam distúrbios fisiológicos em plantas sensíveis, a exemplo das trocas gasosas em genótipos de citros, podendo-se identificar, a partir dessas variáveis, genótipos tolerantes e a resposta das plantas à salinidade. Assim, objetivou-se avaliar a tolerância de genótipos de citros à salinidade na fase de formação de porta-enxertos. O experimento foi desenvolvido em casa de vegetação, no Município de Pombal, Paraíba, empregando-se o delineamento experimental de blocos casualizados com três repetições e tratamentos arranjados em esquema fatorial, 5x8, relativos à combinação de: [i] cinco níveis de salinidade da água de irrigação (0,8; 1,6; 2,4; 3,2 e 4,0 dS m-1) e [ii] oito genótipos de porta-enxertos de citros: 1. limoeiro Cravo Santa Cruz (LCRSTC); 2. tangerineira Sunki comum (TSKC) x citrumelo Swingle (CTSW) - 028; 3. TSKC x CTSW - 033; 4. TSKC x CTSW - 041; 5. limoeiro Volkameriano (LVK) x limoeiro Cravo (LCR) - 038; 6. tangerineira Sunki da Flórida (TSKFL); 7. TSKC e 8. limoeiro Rugoso da Flórida (LRF). Avaliaram-se as trocas gasosas das plantas aos 15, 30 e 60 dias após o início da aplicação de água salina. A salinidade da água reduziu as trocas gasosas de genótipos de citros, sendo mais evidente aos 15 dias após o início do estresse. Os genótipos limoeiro ‘Cravo Santa Cruz, TSKC x CTSW 041, LVK x LCR 038 e o limoeiro Rugoso da Flórida têm comportamento fisiológico satisfatório durante os primeiros 30 dias de exposição ao estresse, sendo moderadamente tolerantes ao estresse salino. Os genótipos TSKC x CTSW 033 e a tangerineira Sunki Comum são mais sensíveis à salinidade.(AU)

Effect of soil conditioners on the chemical attributes of a saline-sodic soil and on the initial growth of the castor bean plant / Uso de condicionadores nos atributos químicos de um solo salino-sódico e no crescimento inicial de mamoneira

This work aimed to study the effect of chemical and organic conditioners on the chemical attributes of a saline-sodic soil and on the initial growth of two castor bean cultivars. Two experiments were performed in the green house of the Center of Human and Agrarian Sciences of the Paraíba State University (CCHA-UEPB), Campus IV, Catolé do Rocha-PB. In the first experiment, an entirely randomized experimental design with five treatments [(saline sodic soil without conditioners (SSC), saline sodic soil + biofertilizer at 10% of the soil volume (SS + B), saline sodic soil + chalk at 100% of the chalk requirement (SS + C), saline sodic soil + chalk + biofertilizer (SS + C + B), and non-saline soil (NSL)] and eight replicates was adopted. In the second randomized experiment the treatments were displayed in a 5 × 2 factorial scheme, referring to the five corrective treatments used in the first experiment and the two castor bean plant cultivars (BRS Nordestina and BRS Paraguaçu), with four replicates. The application of chalk combined with biofertilizer promoted a better initial development of the castor bean plant in comparison with other recovering treatments. This indicates the corrective effect of chalk on sodicity and of both treatments on the nutrient availability for the plants. The bovine biofertilizer alone did not reduce the sodicity of the sodic saline soil. Under...(AU)

O objetivo do trabalho foi estudar a aplicação de condicionadores de natureza química e orgânica nos atributos químicos de um solo salino-sódico e no crescimento inicial de duas cultivares de mamoneira. Dois experimentos foram conduzidos em casa de vegetação do Centro de Ciências Humanas e Agrárias da Universidade Estadual da Paraíba (CCHA-UEPB), Campus IV, Catolé do Rocha-PB. No primeiro experimento adotou-se o delineamento experimental inteiramente casualizado com cinco tratamentos (Solo salino sódico sem corretivo (SSC), Solo salino sódico + biofertilizante à 10% do volume do solo (SS + B), Solo salino sódico + gesso à 100% da necessidade de gesso (SS + G), Solo salino sódico + gesso + biofertilizante (SS + G + B) e solo não salino (SNS)) com 8 repetições e, no segundo experimento, também conduzido em delineamento inteiramente casualizado, os tratamentos foram arranjados em esquema fatorial 5 x 2, referente aos cinco tratamentos de correção obtidos no primeiro experimento e duas cultivares de mamoneira (BRS Nordestina e BRS Paraguaçu), com quatro repetições. A Aplicação de gesso associado ao biofertilizante promoveu o maior desenvolvimento inicial das plantas de mamoneira quando comparado aos demais tratamentos de recuperação e indica ação positiva do gesso como corretivo da sodicidade e de ambos no aumento da disponibilidade de nutrientes às plantas...(AU)

Spectral indices for the detection of salinity effects in melon plants

Water scarcity and soil salinization affect large semiarid agricultural areas throughout the world. The maintenance of agricultural productivity implies better agricultural practices and a careful selection of resistant crops. A proper monitoring of the physiological status of plants can lead to better knowledge of plant nutritional requirements. Visible and near-infrared (VNIR) radiometry provides a non-destructive and quantitative method to monitor vegetation status by quantifying chemical properties using spectroscopic techniques. In this study, the capability of VNIR spectral measurements to detect salinity effects on melon (Cucumis melo L.) plants was tested. Melon plants were cultivated under multiple soil salinity conditions (electrical conductivity, (EC)1:5: 0.5, 1.0 and 2.5 dS m-1). Spectral data of leaves were transformed into vegetation indices indicative of the physiological status of the plants. The results showed differences for N (p 0.05), K and Na content (p 0.01) due to salinity suggesting different degrees of salt stress on the plants. Specific leaf area increased with salinity levels (p 0.001). The capabilities of VNIR radiometry to assess the influence of soil salinity on melon physiology using a non-destructive method were demonstrated. A normalized difference vegetation index (NDVI750-705), and the ratio between water index (WI) and normalized difference vegetation index (WI/NDVI750-705) showed significant relationships (p 0.01) with the salinity. Therefore, this method could be used for in-situ early detection of salinity stress effects.

Spectral indices for the detection of salinity effects in melon plants

Water scarcity and soil salinization affect large semiarid agricultural areas throughout the world. The maintenance of agricultural productivity implies better agricultural practices and a careful selection of resistant crops. A proper monitoring of the physiological status of plants can lead to better knowledge of plant nutritional requirements. Visible and near-infrared (VNIR) radiometry provides a non-destructive and quantitative method to monitor vegetation status by quantifying chemical properties using spectroscopic techniques. In this study, the capability of VNIR spectral measurements to detect salinity effects on melon (Cucumis melo L.) plants was tested. Melon plants were cultivated under multiple soil salinity conditions (electrical conductivity, (EC)1:5: 0.5, 1.0 and 2.5 dS m-1). Spectral data of leaves were transformed into vegetation indices indicative of the physiological status of the plants. The results showed differences for N (p 0.05), K and Na content (p 0.01) due to salinity suggesting different degrees of salt stress on the plants. Specific leaf area increased with salinity levels (p 0.001). The capabilities of VNIR radiometry to assess the influence of soil salinity on melon physiology using a non-destructive method were demonstrated. A normalized difference vegetation index (NDVI750-705), and the ratio between water index (WI) and normalized difference vegetation index (WI/NDVI750-705) showed significant relationships (p 0.01) with the salinity. Therefore, this method could be used for in-situ early detection of salinity stress effects.(AU)