Sources and rates of nitrogen on the nutrition and productive performance of determinate growth habit snap bean / Fontes e doses de nitrogênio na nutrição e desempenho produtivo de feijão-vagem de crescimento determinado

Snap bean is a vegetable crop presenting high requirements of mineral nutrients, such as nitrogen (N). However, studies on the response of this crop to N fertilizationare scarce, mainly with determinate growth habit genotypes, making it difficult to manage thisnutrient supply. The aim of this study was to evaluate the nitrogen nutrition and the productive performance of snap bean withdeterminate growth habit as a function of N sources and rates. The experiment was carried out inpots, under greenhouse conditions, inaEutrophicRed Oxisolwith 36.60 g dm-3of soil organic matter content.The cultivar ‘Macarrãorasteiro’TopSeedwas grownin a completely randomized design at factorial scheme 3x4, with four replications. It was studied three sources of N (urea, ammonium sulfate and sulfammo) and four rates (0, 40, 80 and 120 kg N ha-1), applied20% at sowing time, 40% at 12 days after emergence (DAE) and 40% at 20 DAE.It was evaluatedthe N content of the index leafandtheNaccumulationinshoots, the plant height at the endof the cycle and the number, total fresh mass, mean fresh mass and mean length of pods.The N content of the index leaf and N accumulation in shoots were linearly increased by the N rates, regardless of the N source, while the plant height and the pod’s characteristics werenotinfluenced by anyof the factors studied.

O feijão-vagem é uma hortaliça que apresenta elevada demanda por nutrientes minerais, dentre eles o nitrogênio (N). No entanto, são escassos os estudos de resposta da cultura à adubação nitrogenada, principalmente para cultivares de crescimento determinado, dificultando o manejo de fornecimento do nutriente. O objetivo deste trabalho foi avaliar a nutrição nitrogenada e o desempenho produtivo de feijão-vagem de crescimento determinado em função de fontes e doses de N. O experimento foi conduzido em vasos, sob condições de casa de vegetação, em Latossolo Vermelhoeutróficocom teor de matéria orgânica de 36,60 g dm-3. A variedade ‘Macarrão rasteiro’ TopSeedfoi cultivada em delineamento experimental inteiramente casualizado com esquema fatorial 3x4, com quatro repetições. Estudaram-se três fontes de N (ureia, sulfato de amônio e sulfammo) e quatro doses (0, 40, 80 e 120 kg N ha-1), parceladas 20% na semeadura, 40% aos 12 dias após a emergência (DAE) e 40% aos 20 DAE das plântulas. Foram avaliados o teor de N na folha-índice, o acúmulo de N na parte aérea, a altura das plantas ao final do ciclo, o número, a massa fresca total, a massa fresca médiae o comprimento médio das vagens. O teor foliar e o acúmulo de N na parte aérea das plantas foi aumentado linearmente com as doses, independente da fonte utilizada, enquanto a altura das plantas e as características relacionadas às vagens não foram influenciadas por nenhum dos fatores estudados.

Sources and rates of nitrogen on the nutrition and productive performance of determinate growth habit snap bean / Fontes e doses de nitrogênio na nutrição e desempenho produtivo de feijão-vagem de crescimento determinado

Snap bean is a vegetable crop presenting high requirements of mineral nutrients, such as nitrogen (N). However, studies on the response of this crop to N fertilizationare scarce, mainly with determinate growth habit genotypes, making it difficult to manage thisnutrient supply. The aim of this study was to evaluate the nitrogen nutrition and the productive performance of snap bean withdeterminate growth habit as a function of N sources and rates. The experiment was carried out inpots, under greenhouse conditions, inaEutrophicRed Oxisolwith 36.60 g dm-3of soil organic matter content.The cultivar ‘MacarrãorasteiroTopSeedwas grownin a completely randomized design at factorial scheme 3x4, with four replications. It was studied three sources of N (urea, ammonium sulfate and sulfammo) and four rates (0, 40, 80 and 120 kg N ha-1), applied20% at sowing time, 40% at 12 days after emergence (DAE) and 40% at 20 DAE.It was evaluatedthe N content of the index leafandtheNaccumulationinshoots, the plant height at the endof the cycle and the number, total fresh mass, mean fresh mass and mean length of pods.The N content of the index leaf and N accumulation in shoots were linearly increased by the N rates, regardless of the N source, while the plant height and the pods characteristics werenotinfluenced by anyof the factors studied.(AU)

O feijão-vagem é uma hortaliça que apresenta elevada demanda por nutrientes minerais, dentre eles o nitrogênio (N). No entanto, são escassos os estudos de resposta da cultura à adubação nitrogenada, principalmente para cultivares de crescimento determinado, dificultando o manejo de fornecimento do nutriente. O objetivo deste trabalho foi avaliar a nutrição nitrogenada e o desempenho produtivo de feijão-vagem de crescimento determinado em função de fontes e doses de N. O experimento foi conduzido em vasos, sob condições de casa de vegetação, em Latossolo Vermelhoeutróficocom teor de matéria orgânica de 36,60 g dm-3. A variedade ‘Macarrão rasteiro TopSeedfoi cultivada em delineamento experimental inteiramente casualizado com esquema fatorial 3x4, com quatro repetições. Estudaram-se três fontes de N (ureia, sulfato de amônio e sulfammo) e quatro doses (0, 40, 80 e 120 kg N ha-1), parceladas 20% na semeadura, 40% aos 12 dias após a emergência (DAE) e 40% aos 20 DAE das plântulas. Foram avaliados o teor de N na folha-índice, o acúmulo de N na parte aérea, a altura das plantas ao final do ciclo, o número, a massa fresca total, a massa fresca médiae o comprimento médio das vagens. O teor foliar e o acúmulo de N na parte aérea das plantas foi aumentado linearmente com as doses, independente da fonte utilizada, enquanto a altura das plantas e as características relacionadas às vagens não foram influenciadas por nenhum dos fatores estudados.(AU)

Decision-making on the optimum timing for nitrogen fertilization on sugarcane ratoon

Low efficiency of nitrogen from fertilizers is a major concern worldwide, threatening the sustainability of sugarcane production. The N use efficiency (NUE) by sugarcane can be improved by adopting better fertilizing management practices, reducing environmental impacts. This work evaluated the effects of varying N rates and time of application on stalks and sugar yield in ratoon harvested early in the crop season. The experimental design was a randomized block in a 2 × 4 factorial design and a control (no N) with five replications, including two application times (45 or 90 DAH – days after harvest) and four N rates (50, 100, 150, or 200 kg N ha−1). The time of N fertilizer application promoted differences in stalk yield, as the cumulative yield of two harvests was increased by 8 % (15 Mg ha−1) at 45 DAH when compared to the application at 90 DAH. The application performed at 45 DAH augmented sugar yield by 10 % (2.8 Mg ha−1 of sugar) in relation to 90 DAH. The N rates that promoted the highest sugarcane yield were, respectively, 122 and 144 kg N ha−1 in the first and second crop cycles. The average economical rates obtained for the first and second agricultural cycles were, respectively, 104 and 127 kg N ha−1, demonstrating that the gains by applying high amounts of fertilizers (rates above 150 kg N ha−1) may not cover the investment.

Decision-making on the optimum timing for nitrogen fertilization on sugarcane ratoon

Low efficiency of nitrogen from fertilizers is a major concern worldwide, threatening the sustainability of sugarcane production. The N use efficiency (NUE) by sugarcane can be improved by adopting better fertilizing management practices, reducing environmental impacts. This work evaluated the effects of varying N rates and time of application on stalks and sugar yield in ratoon harvested early in the crop season. The experimental design was a randomized block in a 2 × 4 factorial design and a control (no N) with five replications, including two application times (45 or 90 DAH days after harvest) and four N rates (50, 100, 150, or 200 kg N ha−1). The time of N fertilizer application promoted differences in stalk yield, as the cumulative yield of two harvests was increased by 8 % (15 Mg ha−1) at 45 DAH when compared to the application at 90 DAH. The application performed at 45 DAH augmented sugar yield by 10 % (2.8 Mg ha−1 of sugar) in relation to 90 DAH. The N rates that promoted the highest sugarcane yield were, respectively, 122 and 144 kg N ha−1 in the first and second crop cycles. The average economical rates obtained for the first and second agricultural cycles were, respectively, 104 and 127 kg N ha−1, demonstrating that the gains by applying high amounts of fertilizers (rates above 150 kg N ha−1) may not cover the investment.(AU)

Grain yield, efficiency and the allocation of foliar N applied to soybean canopies

Soybean [Glycine max (L.) Merr.] grain yield is closely associated with the level of optimal nitrogen (N) supply, especially during the reproductive stages. Foliar fertilization with low rates of N have been considered as a strategy for furnishing additional N and enhancing grain yields. Field studies using 15N tracer were conducted over two growing seasons to investigate the impact of foliar N fertilization on grain yield, plant N content, the amount of N derived from fertilizer (NDFF) and N recovery efficiency (NRE). Four foliar N rates (0, 1300, 2600 and 3900 g ha−1) were supplied by two equal split applications at the R1 and R3 stages. Foliar N fertilization of soybean canopies did not affect grain yield, grain N content, shoot N content nor plant N content. Total NDFF was increased from 0.7 to 2.0 kg ha−1 across the N rates. Nonetheless, NRE was unaffected by foliar N fertilization, which averaged 53 %. Soybean plants allocated the same amount of N fertilizer to both grains and shoots. No significant effects of low rate foliar N fertilization were registered on soybean grain yield nor plant N content, despite considerable N fertilizer recovery by plant organs.

Grain yield, efficiency and the allocation of foliar N applied to soybean canopies

Soybean [Glycine max (L.) Merr.] grain yield is closely associated with the level of optimal nitrogen (N) supply, especially during the reproductive stages. Foliar fertilization with low rates of N have been considered as a strategy for furnishing additional N and enhancing grain yields. Field studies using 15N tracer were conducted over two growing seasons to investigate the impact of foliar N fertilization on grain yield, plant N content, the amount of N derived from fertilizer (NDFF) and N recovery efficiency (NRE). Four foliar N rates (0, 1300, 2600 and 3900 g ha−1) were supplied by two equal split applications at the R1 and R3 stages. Foliar N fertilization of soybean canopies did not affect grain yield, grain N content, shoot N content nor plant N content. Total NDFF was increased from 0.7 to 2.0 kg ha−1 across the N rates. Nonetheless, NRE was unaffected by foliar N fertilization, which averaged 53 %. Soybean plants allocated the same amount of N fertilizer to both grains and shoots. No significant effects of low rate foliar N fertilization were registered on soybean grain yield nor plant N content, despite considerable N fertilizer recovery by plant organs.(AU)