Suchergebnisse

O uso de métodos estatísticos para avaliar o crescimento e produção das plantas é crucial para o avanço tecnológico do feijoeiro. A pesquisa teve por objetivo dimensionar a amostra para a estimação da média de caracteres avaliados em diferentes cultivares e condições hídricas. Os dados foram coletados quinzenalmente a partir de dois experimentos fatoriais 3 x 2 (3 cultivares: Triunfo, Garapiá e FC104; 2 regimes hídricos: irrigado, não irrigado). Foram coletados dezoito caracteres (estatura, diâmetro da haste, número de nós, comprimento da raiz, massa fresca e seca da parte aérea e raízes, temperatura foliar, área foliar, número de nódulos, massa fresca e seca dos nódulos, número de vagens, comprimento das vagens, grãos por vagem, grãos por planta e massa seca dos grãos). O tamanho da amostra foi determinado através do método de reamostragem boodstrap a partir de de 2.000 reamostragens, e foi definido pelo número de plantas a partir das quais o intervalo de confiança de 95% foi de 10% a 40% da estimativa média. Como resultado, o tamanho da amostra é diferente entre os caracteres e entre as cultivares e condições hídricas utilizadas. No intervalo de confiança de 95% com erro padrão de 40% da estimativa da média, para avaliar todos os caracteres analisados são necessárias 44 plantas dos caracteres de parte aérea, 132 plantas para os caracteres de raiz e 12 plantas nos caracteres produtivos. Para analisar os dezoito caracteres estudados são necessárias 132 plantas.

The influence of water deficit on plant physiological and biochemical responses as measured by the fraction of transpirable soil water (FTSW) has not been investigated in cultivars developed by the world's largest soybean producer. This information can help obtain plants with improved tolerance to the abiotic stress that most affects soybean production in Brazil, enabling adaptation to edaphoclimatic conditions to enhance the crop's yield potential. We aim to determine the FTSW threshold for transpiration and evaluate changes in the growth, physiological activities, and biochemical and antioxidant responses of soybean cultivars. Three trials were sown on 11/19/2018 (T1), 12/28/2018 (T2), and 9/9/2019 (T3), representing almost the entire soybean sowing window in Brazil. The estimated FTSW threshold values were 0.33, 0.29, and 0.31 in T1; 0.35, 0.41, and 0.43 in T2; and 0.31, 0.49, and 0.45 in T3 for cultivars BMX GARRA IPRO, DM 66I68 RSF IPRO, and NA 5909 RG, respectively. In the three trials, NA 5909 RG showed the greatest height. The POD enzyme was activated in non-irrigated plants in T2 only in cvs. DM 66I68 RSF IPRO and NA 5909 RG. We conclude that cvs. DM 66I68 RSF IPRO and NA 5909 RG showed a more efficient stomatal control, conserving soil water for a longer time, which indicates greater tolerance to water deficit.

The aim of this study was to develop mathematical models to estimate the leaf area of common bean (Phaseolus vulgaris) in irrigated and non-irrigated water regimes from linear dimensions. An experiment was carried out in a completely randomized design with a 3×2 factorial arrangement (three cultivars: Triunfo, Garapiá and FC 104; two water regimes: irrigated and non-irrigated) with 25 replicates each. A total of 523 trifoliates were collected throughout the crop cycle. The length (L, cm) and width (W, cm) of the central leaflet of the trifoliate were measured and their product (LW) (cm²) calculated. Then, the leaf area of these trifoliates was determined by digital photography methods using ImageJ® software, and using leaf discs. The number of samples required to estimate the leaf area of a trifoliate was determined to define which method is the most accurate to be used as the real leaf area in generating equations to estimate the leaf area in common bean. The relationship between area by digital photographs and the dimensions of the central leaflet of the trifoliate (L, W and LW) was fitted by linear, quadratic and power models. Subsequently, the predictive capacity of the equations was assessed by the root mean square error (cm2 trifoliate-1), mean absolute error (cm2 trifoliate-1), index of agreement and Pearson's correlation coefficient. Sample size varied between cultivars, water regimes and evaluation methods. It is more appropriate to use the leaf area provided by ImageJ® as real for comparison purposes in generating models to estimate leaf area from linear measurements, in common bean. The general equation LA = 1.092L1.945 can be used in the tested regimes without accuracy losses.