Interação competitiva e nível de dano econômico de azevém daninho emhíbridos de canola / Competitive interaction and economic damage level of ryegrass harmfulg in canola hybrids

Na canola ocorrem perdas de produtividade e da qualidade de grãos em função da interferência causada pelo azevém (Lolium multiflorum). Diante disso, objetivou-se avaliar a interferência e identificar variáveis explicativas visando determinar o nível de dano econômico (NDE) de diferentes densidades do azevém infestante de híbridos de canola. O experimento foi instalado em delineamento de blocos casualizados, com uma repetição. Os tratamentos foram compostos pelos híbridos de canola (Hyola 433, Hyola 61, Alht B4, Hyola 575 CL e Hyola 76) e 12 densidades de azevém, de 0 até 260 plantas m-2, em competição com a cultura. Avaliou-se aos 50 dias após a emergência das plantas as variáveis densidades de plantas, área foliar, cobertura de solo e massa seca da parte aérea do azevém. A produtividade de grãos, custo de controle, preço de grãos e eficiência de controle foram determinados na canola. A cobertura do solo apresentou melhor ajuste ao modelo da hipérbole retangular estimando adequadamente as perdas de produtividades de grãos pela interferência do azevém. Os híbridos de canola Hyola 433, Hyola 575 CL e Hyola 76 foram os mais competitivos ao se comparar com os demais na presença do azevém, porém demonstraram as menores produtividades de grãos e também os que apresentaram os maiores valores de NDE. Os híbridos de canola Hyola 433 e Hyola 575 CL apresentaram os maiores valores de NDE com 3,85 a 5,13 plantas m-2 em todas as simulações realizadas, respectivamente. Os menores valores de NDE foram obtidos com os híbridos Hyola 61, Alht B4 e Hyola 76 com variações médias de 1,02 à 2,15 plantas m-2, respectivamente. A produtividade de grãos de canola, o preço da saca, a eficiência do herbicida e a redução no custo de controle, causam variação dos valores do NDE.(AU)

In canola, yield and grain quality losses occur due to the interference caused by ryegrass (Lolium multiflorum) when infesting the crop. Thus, the objective was to evaluate the interference and identify explanatory variables seeking to determine the level of economic damage (NDE) of different densities of ryegrass infesting canola hybrids. The experiment was carried out in a randomized block design, with one replication. The treatments consisted of five canola hybrids (Hyola 433, Hyola 61, Alht B4, Hyola 575 CL and Hyola 76) and 12 ryegrass densities, from 0 to 260 plants m-2, in competition with the crop. At 50 days after plant emergence, the variables as plant densities, leaf area, soil cover and shoot dry matter of ryegrass plants were evaluated. Grain yield, control cost, grain price and control efficiency were determined in canola plants. The soil cover presented the best fit to the rectangular hyperbola model, adequately estimating the grain yield losses due to ryegrass interference. The canola hybrids Hyola 433 and Hyola 575 CL were the most competitive when compared to the others in the presence of the competitor, with higher values of EDL. The canola hybrids Hyola 433 and Hyola 575 CL showed the highest EDL values with 3.85 to 5.13 plants m-2in all simulations performed, respectively. The lowest EDL values were obtained with hybrids Hyola 61, Alht B4and Hyola 76 with average variations of 1.02 to 2.15 plants m-2, respectively. The canola grain yield, grain bag price, efficiency of the herbicide, and the reduction in the control cost cause variation in the economic damage level values.(AU)

Breed and heterosis effects on reproduction and production traits of Girolando cows

The objective of this study was to evaluate the breed and heterosis effects on reproductive traits, test-day milk yield, and 305-day milk yield in different lactations of crossbred Girolando cows. Data consisted of test-day milk yield records of first (118,831 records), second (63,227), and third lactation (44,512) and their relative productive (test-day milk yield, 305-day milk yield, and lactation length) and reproductive (age at first calving, calving interval, days open, and dry period) records of 35,582 Girolando cows from Brazil, collected from 1998 to 2014. The heterosis effect of the evaluated traits in Girolando cattle was estimated by MIXED procedure in SAS. Girolando cows showed a negative (favorable) and significant heterosis effect for reproductive traits. The dry periods between the first and second calving and between the second and third calving showed the greatest gains in heterosis (21.93 and 10.41%, respectively). All the evaluated productive traits showed a significant and similar heterosis effect between the three lactations. The use of crossbreeding strategies between the Holstein and Gyr breeds, instead of using the pure breed, is indeed a good alternative to increase the economic efficiency of the dairy activity in the different production systems in tropical environments.(AU)

Low fertilizer inputs do not adversely affect yield or performance of Indica hybrid rice

The enhancement of rice production numbers can be achieved by using quality rice cultivars and fertilizers. The double rice cropping model has given rise to an important rice production system in southern China. Exploring the possibility of whether hybrid vigor could make a substantial contribution to early and late season rice production, and how the heterosis expression of hybrid rice functions under different levels of fertilizer application is of great significance. The objective of this study was to evaluate the grain yield and associated plant traits of popular hybrid and inbred rice varieties with large-scale promotion under conditions of customary (high) and combined (low) fertilization in the early and late seasons of 2017-18 in Changsha County, Hunan Province, China. We found that hybrid rice varieties displayed their respective advantages in the early and late rice seasons, but the advantages in their relative yield traits varied. The leading advantages of early season rice were effective panicle number per hill (EPN), 1000-grain weight (KGW), harvest index (HI), yield, and nitrogen use efficiency (NUE), whereas in late season rice, the foremost advantages were grain number per panicle (GNP), HI, yield, and NUE. The EPN was the prime advantage of early season hybrid rice with a short growth period, and the GNP was the main advantage of late season hybrid rice with a long growth period. Notably, the main yield advantage of hybrid rice was stronger under combined (low) fertilization than under customary (high) fertilization. Hence, high yield can be achieved by selecting the best hybrid rice varieties supported by combined fertilization (lower fertilizer use with higher efficiency).

Components of seed production and ergot resistance used as criteria for selection of Brachiaria hybrids

Ergot is a fungal disease and causes reductions in seed productivity and quality. We aimed to identify promising genotypes of brachiaria evaluating: (1) seed production potential (number of tillers, racemes per inflorescence, spikelets per raceme, raceme length, weight and number of seeds, and germination) and (2) resistance of seeds to Ergot (infected tillers, infected seeds). Five genotypes of Brachiaria grasses, four non-natural hybrids named BH1619, BH1810, BH1516 and Mavuno Palisadegrass (Urochloa brizantha x Urochloa ruziziensis), and Marandu Palisadegrass (U. brizantha Hoechst cv. Marandu) were evaluated. The BH1619 hybrid, despite the high weight of seeds, produced less viable, pure seeds. The hybrid BH1516 had a lower percentage of flowered tillers (42%) and seeds infected with ergot (8%). Marandu Palisadegrass had a higher percentage of infected tillers (95%) and infected seeds (38%). The hybrid BH1516 was the most resistant to ergot, followed by Mavuno Palisadegras sand BH1619. Among all materials, Mavuno Palisadegrass and BH1516 have a higher potential for seed production due to the higher percentage of flowered tillers and production of pure seeds with high germination capacity. The BH1516 hybrid was resistant to ergot, making it a better choice for use in infected areas used for seed or forage production.(AU)

Morphometric measurements of calves of beef cattle from different genetic groups up to one year of age

Heterosis plays an important role on yield and profitability of beef production systems. This study evaluates the morphometrics of purebred Nellore (N) and Charolais (C) animals and of the second (G2) and third (G3) generations of their alternating crosses, regarding the effects of genetic group and heterosis from birth to 365 days of age. The experiment comprised 159 calves (C = 29, N = 22, G2 - 3/4C 1/4N = 21, 3/4N 1/4C = 9, G3-5/8C 3/8N = 44 and 5/8N 3/8C = 34). The foreshank girth (FG), thoracic girth (TG), body length (BL), and hip height (HH) were measured after birth, and at 63, 210, and 365 days of age, and the total increases were calculated. The Charolais animals had greater FG, TG, and BL values than Nellore, while the latter had greater HH. For the offspring generations, the predominance of Charolais genes in the genotypes resulted in greater measurements for FG and TG in G2, whereas the predominance of Nellore genes resulted in higher HH values in both generations. The crossbred animals had greater values for all measurements than the purebreds, with more significant differences in FG, TG, and BL compared to Nellore purebreds and in HH compared to Charolais. Charolais animals show higher values for muscularity; while, Nellore animals are taller. Crossbred animals show greater development compared to purebreds, indicating a significant effect of heterosis.

Influência da genética e dos métodos de conservação sobre a qualidade do sêmen suíno / Influence of genetics and conservation methods on the quality of swine semen

A demanda do mercado impulsionou o melhoramento genético na suinocultura caracterizado pelo cruzamento entre linhagens e raças distintas a fim de possibilitar o aproveitamento da heterose. Esse melhoramento acelerado ocorreu em decorrência da inseminação artificial e manipulação do sêmen, associado ao emprego de diluentes e técnicas de refrigeração. Sendo assim, esta revisão tem como objetivo compilar o conhecimento acerca da influência genética e dos métodos de conservação sobre a qualidade do sêmen suíno, além de discutir a composição e eficiência dos principais diluentes e crioprotetores destinados à conservação espermática nesta espécie. Inicialmente, os animais eram selecionados baseados em características produtivas como habilidade materna, qualidade de carcaça e desempenho. Contudo, a fertilidade do reprodutor, caraterizada pela qualidade espermática e libido, é extremamente importante para indústria suinícola uma vez que determina, o potencial produtivo do plantel indiretamente. Evidências demonstram que os parâmetros espermáticos sofrem influência da genética, sendo que cada raça se destaca numa determinada característica seminal. Além disso, o manejo, idade, alimentação, sazonalidade, as características intrínsecas do espermatozoide e os métodos de conservação do ejaculado também determinam sua viabilidade. Apesar de preconizado devido à fácil execução e ótimos resultados, o sêmen refrigerado tem como limitador a produção excessiva de espécies reativas de oxigênio. Da mesma forma, o congelamento do ejaculado promove alterações espermáticas em virtude do choque térmico. Sendo assim, o emprego de diluentes e crioprotetores propícios que possibilitem a manutenção a longo prazo da viabilidade espermática é imprescindível para ambos os processos.

The market demand promoted the genetic improvement in swine farming characterized by the crossing between different strains and breeds to make possible the use of heterosis. This accelerated improvement occurred due to artificial insemination and semen manipulation, associated with the use of extenders and refrigeration techniques. Therefore, this review aims to compile knowledge about the genetic influence and conservation methods on the quality of swine semen, besides to discussing the composition and efficiency of the main extenders and cryoprotectants intended for sperm conservation in this species. Initially, animals were selected based on productive traits such as maternal ability, carcass quality, and performance. However, male fertility, characterized by sperm quality and libido, is extremely important for the swine industry as it determines the productive potential of the herd indirectly. Evidences demonstrates that sperm parameters are influenced by genetics, with each race standing out in certain seminal trait. In addition, the management, age, feeding, seasonality, the intrinsic characteristics of the sperm cell, and the methods of ejaculate conservation also determine its viability. Despite being recommended due to its easy execution and excellent results, refrigerated semen has the excessive production of reactive oxygen species as a limiter. Likewise, the ejaculate freezing promotes sperm changes due to heat shock. Therefore the use of suitable extenders and cryoprotectants that allow the long-term maintenance of sperm viability is essential for both processes.

Perspectives of gene editing for cattle farming in tropical and subtropical regions

Cattle productivity in tropical and subtropical regions can be severely affected by the environment. Reproductive performance, milk and meat production are compromised by the heat stress imposed by the elevated temperature and humidity. The resulting low productivity contributes to reduce the farmer's income and to increase the methane emissions per unit of animal protein produced and the pressure on land usage. The introduction of highly productive European cattle breeds as well as crossbreeding with local breeds have been adopted as strategies to increase productivity but the positive effects have been limited by the low adaptation of European animals to hot climates and by the reduction of the heterosis effect in the following generations. Gene editing tools allow precise modifications in the animal genome and can be an ally to the cattle industry in tropical and subtropical regions. Alleles associated with production or heat tolerance can be shifted between breeds without the need of crossbreeding. Alongside assisted reproductive biotechnologies and genome selection, gene editing can accelerate the genetic gain of indigenous breeds such as zebu cattle. This review focuses on some of the potential applications of gene editing for cattle farming in tropical and subtropical regions, bringing aspects related to heat stress, milk yield, bull reproduction and methane emissions.(AU)

Breed, heterosis, and recombination effects for lactation curves in Brazilian cattle

The objective of this study was to estimate the breed, heterosis, and recombination effects on different components of the lactation curve of Girolando cattle. The dataset used consisted of 12,121 purebred cows of Holstein (H) and Gyr (G) breeds, and six H×G crossbred cows (Girolando). The model used presents random effects of herd and cow, regression coefficient associated with linear effect of proportion of H breed, regression coefficient associated with the linear effect of heterosis between H and G breeds, regression coefficient associated with the linear effect of recombination between H and G breeds, and random effect of residual. Dijkstra's (DJ), Nelder's (ND), Wilmink's (WL), and Wood's (WD) models were tested to fit production records of these different genetic groups. These models were then tested according to evaluation criteria of quality of fit (AIC, BIC, and RMSE), and the two best models (WD and WL) were chosen for estimation of 305-day milk yield (MY305), peak yield, time to peak, and persistency of milk yield. The breed effect was significant for all traits and components of the lactation curve. The heterosis effect was significant for all traits, and was more significant for MY305 (945.62±79.17 kg). Peak yield was the component of lactation curve that presented the most significant heterosis effect, partially explaining the heterosis effect (12 to 21%) found for MY305. The recombination effect was positive only for lactation period and time to peak of lactation in Girolando cows.

Root morphological traits of oil palm genotypes with differential resistance to fatal yellowing / Características morfológicas radiculares de genótipos de palma de óleo com resistência diferencial ao Amarelecimento Fatal

Brazil has an extensive area where the climate and soil are suitable for oil palm growing. However, in part of this area, production has been limited by the occurrence of the fatal yellowing (FY) anomaly, whose initial symptom is the rotting of absorptive roots. This symptom can be more severe in oil palm genetic materials with a smaller root system. The aim of this study was to examine morphological traits of roots and shoots of seedlings of three oil palm genotypes with different degrees of resistance to FY, namely, Tenera (sensitive), Caiaué (resistant) and Interspecific Hybrid (resistant) to provide bases to elucidate the differential resistance of these materials to FY. Shoot biomass did not vary statistically between the genetic materials. The mass, length and area of fine and very fine roots were significantly higher in the Interspecific Hybrid than in Caiaué and Tenera. The fine and very fine roots of Interspecific Hybrid had a larger mass than Caiaué (114 and 133%, respectively) and Tenera (216 and 178%, respectively). The Interspecific Hybrid also exhibited higher values for the length of fine and very fine roots than Caiaué (155 and 99% respectively) and Tenera (228 and 94% respectively). The root traits of the Interspecific Hybrid and Tenera are compatible with their differential resistance to FY. Our results demonstrate the importance of expanding the study of the relationship between root morphology and resistance to FY in these genetic materials under conditions that favor the occurrence of the anomaly, such as flooding.

O Brasil possui uma extensa área com clima e solo aptos ao plantio de palma de óleo. No entanto, a produção em parte desta área tem sido limitada pela ocorrência da anomalia Amarelecimento Fatal (AF),cujo sintoma inicial é o apodrecimento das raízes de absorção. Esse sintoma pode ser mais severo em materiais genéticos de palma de óleo que apresentem sistema radicular reduzido. O objetivo foi avaliar características morfológicas de raízes e parte aérea de mudas de três genótipos de palma de óleo com graus diferentes de resistência ao AF: Tenera (sensível), Caiaué (resistente) e Híbrido Interespecífico (resistente)para fornecer subsídios ao entendimento da resistência diferencial desses materiais ao AF. A biomassa da parte aérea não variou estatisticamente entre os materiais genéticos. Massa, comprimento e área de raízes finas e muito finas foram significativamente maiores no Híbrido Interespecífico do que no Caiaué e no Tenera. O Híbrido Interespecífico apresentou valores de massa de raízes finas e muito finas superiores em relação ao Caiaué (114 e 133%, respectivamente) e Tenera (216 e 178%, respectivamente). O Híbrido Interespecífico também apresentou valores superiores de comprimento de raízes finas e muito finas em relação ao Caiaué (155 e 99% respectivamente) e Tenera (228 e 94% respectivamente). As características radiculares do Híbrido Interespecífico e do Tenera são compatíveis com sua resistência diferencial ao AF. Nossos resultados demonstram a importância de ampliar o estudo da relação entre morfologia radicular e resistência ao AF destes materiais genéticos em condições que favoreçam a ocorrência da anomalia, como alagamento.

Root morphological traits of oil palm genotypes with differential resistance to fatal yellowing / Características morfológicas radiculares de genótipos de palma de óleo com resistência diferencial ao Amarelecimento Fatal

Brazil has an extensive area where the climate and soil are suitable for oil palm growing. However, in part of this area, production has been limited by the occurrence of the fatal yellowing (FY) anomaly, whose initial symptom is the rotting of absorptive roots. This symptom can be more severe in oil palm genetic materials with a smaller root system. The aim of this study was to examine morphological traits of roots and shoots of seedlings of three oil palm genotypes with different degrees of resistance to FY, namely, Tenera (sensitive), Caiaué (resistant) and Interspecific Hybrid (resistant) to provide bases to elucidate the differential resistance of these materials to FY. Shoot biomass did not vary statistically between the genetic materials. The mass, length and area of fine and very fine roots were significantly higher in the Interspecific Hybrid than in Caiaué and Tenera. The fine and very fine roots of Interspecific Hybrid had a larger mass than Caiaué (114 and 133%, respectively) and Tenera (216 and 178%, respectively). The Interspecific Hybrid also exhibited higher values for the length of fine and very fine roots than Caiaué (155 and 99% respectively) and Tenera (228 and 94% respectively). The root traits of the Interspecific Hybrid and Tenera are compatible with their differential resistance to FY. Our results demonstrate the importance of expanding the study of the relationship between root morphology and resistance to FY in these genetic materials under conditions that favor the occurrence of the anomaly, such as flooding.(AU)

O Brasil possui uma extensa área com clima e solo aptos ao plantio de palma de óleo. No entanto, a produção em parte desta área tem sido limitada pela ocorrência da anomalia Amarelecimento Fatal (AF),cujo sintoma inicial é o apodrecimento das raízes de absorção. Esse sintoma pode ser mais severo em materiais genéticos de palma de óleo que apresentem sistema radicular reduzido. O objetivo foi avaliar características morfológicas de raízes e parte aérea de mudas de três genótipos de palma de óleo com graus diferentes de resistência ao AF: Tenera (sensível), Caiaué (resistente) e Híbrido Interespecífico (resistente)para fornecer subsídios ao entendimento da resistência diferencial desses materiais ao AF. A biomassa da parte aérea não variou estatisticamente entre os materiais genéticos. Massa, comprimento e área de raízes finas e muito finas foram significativamente maiores no Híbrido Interespecífico do que no Caiaué e no Tenera. O Híbrido Interespecífico apresentou valores de massa de raízes finas e muito finas superiores em relação ao Caiaué (114 e 133%, respectivamente) e Tenera (216 e 178%, respectivamente). O Híbrido Interespecífico também apresentou valores superiores de comprimento de raízes finas e muito finas em relação ao Caiaué (155 e 99% respectivamente) e Tenera (228 e 94% respectivamente). As características radiculares do Híbrido Interespecífico e do Tenera são compatíveis com sua resistência diferencial ao AF. Nossos resultados demonstram a importância de ampliar o estudo da relação entre morfologia radicular e resistência ao AF destes materiais genéticos em condições que favoreçam a ocorrência da anomalia, como alagamento.(AU)

Genetic diversity and heterotic grouping of sorghum lines using SNP markers

Sorghum breeding programs are based predominantly on developing homozygous lines to produce single cross hybrids, frequently with relatively narrow genetic bases. The adoption of complementary strategies, such as genetic diversity study, enables a broader vision of the genetic structure of the breeding germplasm. The purpose of this study was to evaluate the genetic diversity of sorghum breeding lines using structure analysis, principal components (PC) and clustering analyses. A total of 160 sorghum lines were genotyped with 29,649 SNP markers generated by genotyping-by-sequencing (GBS). The PC and clustering analyses consistently divided the R (restorer) and B (maintainer) lines based on their pedigree, generating four groups. Thirty-two B and 21 R lines were used to generate 121 single-cross hybrids, whose performances were compared based on the diversity clustering of each parental line. The genetic divergence of B and R lines indicated a potential for increasing heterotic response in the development of hybrids. The genetic distance was correlated to heterosis, allowing for the use of markers to create heterotic groups in sorghum.(AU)

Genetic diversity and heterotic grouping of sorghum lines using SNP markers

Sorghum breeding programs are based predominantly on developing homozygous lines to produce single cross hybrids, frequently with relatively narrow genetic bases. The adoption of complementary strategies, such as genetic diversity study, enables a broader vision of the genetic structure of the breeding germplasm. The purpose of this study was to evaluate the genetic diversity of sorghum breeding lines using structure analysis, principal components (PC) and clustering analyses. A total of 160 sorghum lines were genotyped with 29,649 SNP markers generated by genotyping-by-sequencing (GBS). The PC and clustering analyses consistently divided the R (restorer) and B (maintainer) lines based on their pedigree, generating four groups. Thirty-two B and 21 R lines were used to generate 121 single-cross hybrids, whose performances were compared based on the diversity clustering of each parental line. The genetic divergence of B and R lines indicated a potential for increasing heterotic response in the development of hybrids. The genetic distance was correlated to heterosis, allowing for the use of markers to create heterotic groups in sorghum.

Root morphological traits of oil palm genotypes with differential resistance to fatal yellowing / Características morfológicas radiculares de genótipos de palma de óleo com resistência diferencial ao Amarelecimento Fatal

Brazil has an extensive area where the climate and soil are suitable for oil palm growing. However, in part of this area, production has been limited by the occurrence of the fatal yellowing (FY) anomaly, whose initial symptom is the rotting of absorptive roots. This symptom can be more severe in oil palm genetic materials with a smaller root system. The aim of this study was to examine morphological traits of roots and shoots of seedlings of three oil palm genotypes with different degrees of resistance to FY, namely, Tenera (sensitive), Caiaué (resistant) and Interspecific Hybrid (resistant) to provide bases to elucidate the differential resistance of these materials to FY. Shoot biomass did not vary statistically between the genetic materials. The mass, length and area of fine and very fine roots were significantly higher in the Interspecific Hybrid than in Caiaué and Tenera. The fine and very fine roots of Interspecific Hybrid had a larger mass than Caiaué (114 and 133%, respectively) and Tenera (216 and 178%, respectively). The Interspecific Hybrid also exhibited higher values for the length of fine and very fine roots than Caiaué (155 and 99% respectively) and Tenera (228 and 94% respectively). The root traits of the Interspecific Hybrid and Tenera are compatible with their differential resistance to FY. Our results demonstrate the importance of expanding the study of the relationship between root morphology and resistance to FY in these genetic materials under conditions that favor the occurrence of the anomaly, such as flooding.(AU)

O Brasil possui uma extensa área com clima e solo aptos ao plantio de palma de óleo. No entanto, a produção em parte desta área tem sido limitada pela ocorrência da anomalia Amarelecimento Fatal (AF), cujo sintoma inicial é o apodrecimento das raízes de absorção. Esse sintoma pode ser mais severo em materiais genéticos de palma de óleo que apresentem sistema radicular reduzido. O objetivo foi avaliar características morfológicas de raízes e parte aérea de mudas de três genótipos de palma de óleo com graus diferentes de resistência ao AF: Tenera (sensível), Caiaué (resistente) e Híbrido Interespecífico (resistente) para fornecer subsídios ao entendimento da resistência diferencial desses materiais ao AF. A biomassa da parte aérea não variou estatisticamente entre os materiais genéticos. Massa, comprimento e área de raízes finas e muito finas foram significativamente maiores no Híbrido Interespecífico do que no Caiaué e no Tenera. O Híbrido Interespecífico apresentou valores de massa de raízes finas e muito finas superiores em relação ao Caiaué (114 e 133%, respectivamente) e Tenera (216 e 178%, respectivamente). O Híbrido Interespecífico também apresentou valores superiores de comprimento de raízes finas e muito finas em relação ao Caiaué (155 e 99% respectivamente) e Tenera (228 e 94% respectivamente). As características radiculares do Híbrido Interespecífico e do Tenera são compatíveis com sua resistência diferencial ao AF. Nossos resultados demonstram a importância de ampliar o estudo da relação entre morfologia radicular e resistência ao AF destes materiais genéticos em condições que favoreçam a ocorrência da anomalia, como alagamento.(AU)

Identifying parents and generating hybrids with high combining ability for yielding fresh cocoon and raw silk in silkworm (Bombxy mori L)

This study was carried out to identify parents and hybrids by determination of general combining ability (GCA), specific combining ability (SCA), and heterosis in pure lines and their hybrids, which were selected from our gene sources, to determine new hybrid combinations that could be alternative or higher in yielding compared with M × N hybrid used in production. Combining ability and heterosis effects were studied for the eight quantitative characters through line × tester mating design. Chinese origin lines (KZ, ZF) were identified as females and Japanese origin lines (BR, ZB) as males, and by these, four hybrids were derived. M, N, and their hybrid were both used as control genotypes and to calculate the heterosis and commercial heterosis as well. All the genotypes were reared in standard conditions, in three replications. ZF (for pupa survival rate) and ZB (for hatching and filament length) presented significantly higher and positive GCA effects. In addition, ZB had negative GCA effect for infertile egg rate. Effects of SCA were not significant for all the characters. In conclusion, ZF × ZB hybrid could have a potential for the higher cocoon and silk production in Turkey.(AU)

Potential of parents and hybrids experimental of the yellow melon / Potencial de parentais e híbridos experimentais de melão amarelo

Melon or muskmelon (Cucumis melo L.) is of considerable economic importance in Brazil. Nearly all the cultivars currently grown are hybrids. Heterosis has been used to advantage in the melon plant, and the use of uniform hybrids is one of the reasons for successful cultivation. The aim of the present study was to evaluate the agronomic potential of yellow melon lines and hybrids. An experiment was conducted in randomized blocks with three replications to evaluate 24 hybrids generated by crosses among three elite lines used as female parents (AF-01, AF-02, and AF-03) and eight lines used as male parents (LAM-01, LAM-02, LAM-03, LAM-04, LAM-05, LAM-06, LAM-07, and LAM-08). Yield and fruit quality traits were evaluated. Partial diallel analysis was carried out to estimate general combining ability and specific combining ability. Additive and non-additive effects were observed for the yield, mean fruit weight, and pulp thickness traits. The lines AF-02, LAM-02, and LAM-03 are the most promising as parents as they more frequently have favorable alleles. The most prominent hybrids in diallel analysis were AF-02 x LAM-02, AF-02 x LAM-03, AF-02 x LAM-04, and AF-03 x LAM-06.(AU)

O melão amarelo (Cucumis melo L.) é uma hortaliça de grande importância econômica. Atualmente as cultivares plantadas, em quase sua totalidade, são híbridos. A heterose tem sido explorada no meloeiro, sendo o emprego de híbridos uniformes uma das razões do sucesso da cultura. O objetivo do presente trabalho foi avaliar o potencial agronômico de linhagens e híbridos de melão amarelo. Foi conduzido um ensaio em blocos casualizados com três repetições para avaliar 24 híbridos gerados pelos cruzamentos entre três linhagens elites utilizadas como genitores femininos (AF-01, AF-02 e AF-03), e oito linhagens utilizadas como genitores masculinos (LAM-01; LAM-02; LAM-03; LAM-04; LAM-05; LAM-06; LAM-07 e LAM-08). Foram avaliados caracteres a produção e a qualidade do fruto. Realizou-se a análise dialélica parcial para estimação das capacidades geral e específica de combinação. Observou-se efeitos aditivos e não aditivos para os caracteres produtividade, peso médio do fruto e espessura da polpa. As linhagens AF-02, LAM-02 e LAM03 são as mais promissoras por possuir maior frequência de alelos favoráveis. Os híbridos de maior destaque foram AF-02 x LAM-02, AF-02 x LAM-03, AF-02 x LAM-04 e AF-03 x LAM-06.(AU)

Identification and phenotypic characterization of genetic groups of the Girolando breed in dairy herds of the state of Roraima / Identificação e caracterização fenotípica dos grupos genéticos da raça Girolando nos rebanhos leiteiros do estado de Roraima

Dairy farming in the state of Roraima, Brazil, is majorly supported by Holstein x Gir crossbred cattle, which are more adapted to the tropical climate and traditional production systems. However, there is a need to adapt the genetic groups to production systems and raise awareness of the importance of using visual phenotypic assessments as an auxiliary tool in obtaining and selecting animals. This study proposes to identify the frequency and characterize the phenotype of the » Hol + ¾ Gir; ⅜ Hol + ⅝ Gir; ½ Hol + ½ Gir; ⅝Hol + ⅜ Gir; ¾ Hol + » Gir; and ⅞ Hol + ⅛ Gir genetic groups of the Girolando breed in herds in the state of Roraima. Data were obtained from visual morphological evaluations to identify the genetic groups and characterize the phenotype of the animals from August 2016 to February 2017. According to the evaluations, the frequency distribution of the genetic groups was as follows: 210 (21.26%) of the » Hol + ¾ Gir group; 145 (14.68%) of the ⅜ Hol + ⅝ Gir group; 249 (25.20%) of the ½ Hol ½ Gir group; 166 (16.80%) of the ⅝ Hol + ⅜ Gir group; 126 (12.75%) of the ¾ Hol + » Gir group; and 92 (9.3%) of the ⅞ Hol + ⅛ Gir group. In the phenotypic evaluations, statistically significant differences (p<0.05) were detected in the ¾ Hol + » Gir genetic group for overall appearance (OA); in ⅝ Hol + ⅜ Gir and ⅞ Hol + ⅛ Gir for Body Capacity (BC); in ½ Hol + ½ Gir for Dairy Traits (DT); and in ¾ Hol + » Gir and ⅞ Hol + ⅛ Gir for Reproductive System and Feet-Leg Structure (RS/FL). The ½ Hol + ½ Gir genetic group was superior for BC, DT and RS/FL, being best classified as to the Girolando breed type and revealing better characterization and uniformity per selection process.

A pecuária leiteira do Estado de Roraima é sustentada por bovinos mestiços Holandês x Gir, animais mais adaptados ao clima tropical e aos sistemas de produção tradicionais. No entanto, existe a necessidade de adequação dos grupos genéticos aos sistemas de produção e de sensibilizar quanto à importância do uso de avaliações visuais fenotípicas como ferramenta de auxilio na obtenção e seleção dos animais. Os objetivos da pesquisa consistiram em identificar a frequência e caracterizar o fenótipo dos grupos genéticos » Hol + ¾ Gir, ⅜ Hol + ⅝ Gir, ½ Hol + ½ Gir, ⅝ Hol + ⅜ Gir, ¾ Hol + » Gir e ⅞ Hol + ⅛ Gir da raça Girolando nos rebanhos do Estado de Roraima. Os dados foram obtidos a partir de avaliações visuais morfológicas para identificar os grupos genéticos e caracterizar o fenótipo dos animais no período de agosto de 2016 a fevereiro de 2017. A distribuição da frequência dos grupos genéticos de acordo com as avaliações foi de: 210 (21,26%) do grupo » Hol + ¾ Gir; 145 (14,68%) do grupo ⅜ Hol + ⅝ Gir; 249 (25,20%) do grupo ½ Hol ½ Gir; 166 (16,80%) do grupo ⅝ Hol + ⅜ Gir; 126 (12,75%) do grupo ¾ Hol + » Gir e 92 (9,3%) do grupo ⅞ Hol + ⅛ Gir. Nas avaliações fenotípicas foram observadas diferenças estaticamente significativas (p<0,05) no grupo genético ¾ Hol + » Gir para Aparência Geral (AG), nos grupos genéticos ⅝ Hol + ⅜ Gir e ⅞ Hol + ⅛ Gir para Capacidade Corporal (CC), nogrupo ½ Hol + ½ Gir para Características Leiteiras (CL) e nos grupos ¾ Hol + » Gir e ⅞ Hol + ⅛ Gir para Aparelho Reprodutor e Aprumos (AR/A). O grupo genético ½ Hol + ½ Gir foi superior nas características Capacidade Corporal (CC), Características Leiteiras (CL) e Aparelho Reprodutor e Aprumos (AR/A), sendo melhores classificados quanto ao tipo da raça Girolando demonstrando melhor caracterização e uniformização por processo seletivo.

Identification and phenotypic characterization of genetic groups of the Girolando breed in dairy herds of the state of Roraima / Identificação e caracterização fenotípica dos grupos genéticos da raça Girolando nos rebanhos leiteiros do estado de Roraima

Dairy farming in the state of Roraima, Brazil, is majorly supported by Holstein x Gir crossbred cattle, which are more adapted to the tropical climate and traditional production systems. However, there is a need to adapt the genetic groups to production systems and raise awareness of the importance of using visual phenotypic assessments as an auxiliary tool in obtaining and selecting animals. This study proposes to identify the frequency and characterize the phenotype of the » Hol + ¾ Gir; ⅜ Hol + ⅝ Gir; ½ Hol + ½ Gir; ⅝Hol + ⅜ Gir; ¾ Hol + » Gir; and ⅞ Hol + ⅛ Gir genetic groups of the Girolando breed in herds in the state of Roraima. Data were obtained from visual morphological evaluations to identify the genetic groups and characterize the phenotype of the animals from August 2016 to February 2017. According to the evaluations, the frequency distribution of the genetic groups was as follows: 210 (21.26%) of the » Hol + ¾ Gir group; 145 (14.68%) of the ⅜ Hol + ⅝ Gir group; 249 (25.20%) of the ½ Hol ½ Gir group; 166 (16.80%) of the ⅝ Hol + ⅜ Gir group; 126 (12.75%) of the ¾ Hol + » Gir group; and 92 (9.3%) of the ⅞ Hol + ⅛ Gir group. In the phenotypic evaluations, statistically significant differences (p<0.05) were detected in the ¾ Hol + » Gir genetic group for overall appearance (OA); in ⅝ Hol + ⅜ Gir and ⅞ Hol + ⅛ Gir for Body Capacity (BC); in ½ Hol + ½ Gir for Dairy Traits (DT); and in ¾ Hol + » Gir and ⅞ Hol + ⅛ Gir for Reproductive System and Feet-Leg Structure (RS/FL). The ½ Hol + ½ Gir genetic group was superior for BC, DT and RS/FL, being best classified as to the Girolando breed type and revealing better characterization and uniformity per selection process.(AU)

A pecuária leiteira do Estado de Roraima é sustentada por bovinos mestiços Holandês x Gir, animais mais adaptados ao clima tropical e aos sistemas de produção tradicionais. No entanto, existe a necessidade de adequação dos grupos genéticos aos sistemas de produção e de sensibilizar quanto à importância do uso de avaliações visuais fenotípicas como ferramenta de auxilio na obtenção e seleção dos animais. Os objetivos da pesquisa consistiram em identificar a frequência e caracterizar o fenótipo dos grupos genéticos » Hol + ¾ Gir, ⅜ Hol + ⅝ Gir, ½ Hol + ½ Gir, ⅝ Hol + ⅜ Gir, ¾ Hol + » Gir e ⅞ Hol + ⅛ Gir da raça Girolando nos rebanhos do Estado de Roraima. Os dados foram obtidos a partir de avaliações visuais morfológicas para identificar os grupos genéticos e caracterizar o fenótipo dos animais no período de agosto de 2016 a fevereiro de 2017. A distribuição da frequência dos grupos genéticos de acordo com as avaliações foi de: 210 (21,26%) do grupo » Hol + ¾ Gir; 145 (14,68%) do grupo ⅜ Hol + ⅝ Gir; 249 (25,20%) do grupo ½ Hol ½ Gir; 166 (16,80%) do grupo ⅝ Hol + ⅜ Gir; 126 (12,75%) do grupo ¾ Hol + » Gir e 92 (9,3%) do grupo ⅞ Hol + ⅛ Gir. Nas avaliações fenotípicas foram observadas diferenças estaticamente significativas (p<0,05) no grupo genético ¾ Hol + » Gir para Aparência Geral (AG), nos grupos genéticos ⅝ Hol + ⅜ Gir e ⅞ Hol + ⅛ Gir para Capacidade Corporal (CC), nogrupo ½ Hol + ½ Gir para Características Leiteiras (CL) e nos grupos ¾ Hol + » Gir e ⅞ Hol + ⅛ Gir para Aparelho Reprodutor e Aprumos (AR/A). O grupo genético ½ Hol + ½ Gir foi superior nas características Capacidade Corporal (CC), Características Leiteiras (CL) e Aparelho Reprodutor e Aprumos (AR/A), sendo melhores classificados quanto ao tipo da raça Girolando demonstrando melhor caracterização e uniformização por processo seletivo.(AU)

Vigor of red clover seeds under salinity stress / Vigor de sementes de trevo vermelho submetidas a estresse salino

The accelerated aging test is a considerably important method for measuring the physiological potential of seeds. This study sought to apply the accelerated aging test to determine the vigor of red clover seeds of the Quiniquelli and Estanzuela 116 cultivars under water and salinity stress conditions. Accordingly, the seeds were aged for 12, 24, 36, 48, and 72 hours at 42 °C in water and a saturated salt solution (40% NaCl) and then assessed by the accelerated aging test. The lengths of 15 normal seedlings from each of the four replicates for both cultivars were measured, and the seedlings dry mass (48 h/60 °C) was determined. After aging 12, 24, and 36 hours in a saturated salt solution, vigor was above the average of 84.5% for both cultivars. In the test conducted with water, 36 hours were enough to stress the seeds. The accelerated aging time that best represented the vigor of the seeds of the Quiniquelli and Estanzuela 116 cultivars was 48 hours at 42 °C in the saturated NaCl solution, thus being the most suitable for red clover seeds.

O teste de envelhecimento acelerado é de grande importância para expressar o potencial fisiológico das sementes. O objetivo do trabalho foi determinar o vigor de sementes de trevo vermelho das cultivares Quiniquelli e Estanzuela 116 pelo teste do envelhecimento acelerado sob estresse hídrico e salino.  Para tal, as sementes foram expostas a solução hídrica e salina com NaCl (40%) nos tempos de 12, 24, 36, 48 e 72 h a 42 °C e, em seguida, avaliadas pelo teste de envelhecimento acelerado. Foram medidos os comprimentos de 15 plântulas normais de cada uma das quatro repetições de ambas as cultivares e determinada a massa seca das plântulas (48 h /60 °C). Após 12, 24 e 36 h de envelhecimento em solução salina o vigor foi superior à média de 84,5% para ambas cultivares. No teste conduzido com água, o tempo de 36 h foi suficiente para estressar as sementes. O tempo de envelhecimento acelerado que melhor caracterizou o vigor de sementes das cultivares Quiniquelli e Estanzuela 116 foi o de 48 h sob temperatura de 42 °C com o uso de solução saturada de NaCl, sendo o mais indicado para as sementes de trevo vermelho.

Vigor of red clover seeds under salinity stress / Vigor de sementes de trevo vermelho submetidas a estresse salino

The accelerated aging test is a considerably important method for measuring the physiological potential of seeds. This study sought to apply the accelerated aging test to determine the vigor of red clover seeds of the Quiniquelli and Estanzuela 116 cultivars under water and salinity stress conditions. Accordingly, the seeds were aged for 12, 24, 36, 48, and 72 hours at 42 °C in water and a saturated salt solution (40% NaCl) and then assessed by the accelerated aging test. The lengths of 15 normal seedlings from each of the four replicates for both cultivars were measured, and the seedlings dry mass (48 h/60 °C) was determined. After aging 12, 24, and 36 hours in a saturated salt solution, vigor was above the average of 84.5% for both cultivars. In the test conducted with water, 36 hours were enough to stress the seeds. The accelerated aging time that best represented the vigor of the seeds of the Quiniquelli and Estanzuela 116 cultivars was 48 hours at 42 °C in the saturated NaCl solution, thus being the most suitable for red clover seeds.(AU)

O teste de envelhecimento acelerado é de grande importância para expressar o potencial fisiológico das sementes. O objetivo do trabalho foi determinar o vigor de sementes de trevo vermelho das cultivares Quiniquelli e Estanzuela 116 pelo teste do envelhecimento acelerado sob estresse hídrico e salino.  Para tal, as sementes foram expostas a solução hídrica e salina com NaCl (40%) nos tempos de 12, 24, 36, 48 e 72 h a 42 °C e, em seguida, avaliadas pelo teste de envelhecimento acelerado. Foram medidos os comprimentos de 15 plântulas normais de cada uma das quatro repetições de ambas as cultivares e determinada a massa seca das plântulas (48 h /60 °C). Após 12, 24 e 36 h de envelhecimento em solução salina o vigor foi superior à média de 84,5% para ambas cultivares. No teste conduzido com água, o tempo de 36 h foi suficiente para estressar as sementes. O tempo de envelhecimento acelerado que melhor caracterizou o vigor de sementes das cultivares Quiniquelli e Estanzuela 116 foi o de 48 h sob temperatura de 42 °C com o uso de solução saturada de NaCl, sendo o mais indicado para as sementes de trevo vermelho.(AU)

Temperatures and substrates for germination and vigor ofErythroxylum pauferrense Plowman seeds

Erythroxylum pauferrense is an endemic understory plant species of the Northeast Region of Brazil. The species is of great importance to the region and so ecophysiological studies are needed for its preservation. The objective of the present study was to determine the best substrates and temperatures for testing germination and seed vigor of E. pauferrense. An experiment was performed comprising a completely randomized design in a 5 x 4 factorial scheme, with five temperature regimes (20, 25, 30, 35°C constant and 20-30°C alternating) and four types of substrates (paper, vermiculite, sand and commercial substrate). The following characteristics were evaluated: germination percentage, first germination count, germination speed index, mean germination time, seedling length and dry mass (root and shoot). Paper and vermiculite substrates combined with constant temperatures of 20, 25, 30 and alternated between 20-30°C, provide greater seed germination and vigor while 35°C reduces seed physiological quality.