Agronomic performance of common bean cultivars under irrigation levels assessed by spectral indices and modeling

• Autor(a) principal: Coelho, Anderson Prates [UNESP]
• Data de Publicação: 2022
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/216986
• topic: Common beans; Irrigation; Models; Nutrient requirements; Remote sensing

In tropical and subtropical regions of Brazil, the cultivation of common bean can be carried out throughout the year, but it is subject to high variability in climatic conditions. Associated with this are factors such as irrigation, fertilization, and type of cultivars and the technological degree of the farms which also contribute to increasing the variability in crop yield. Studies on these factors and techniques to explain these variations are required to generate specific recommendations in this context. A two-year field experiment was conducted in the winter season in the Southeastern part of Brazil to evaluate, explain, and model the effect of irrigation levels on grain yield, technological and nutritional quality of grains, extraction and export of macronutrients, and define the level of irrigation and the sowing time that provide the best agronomic performance, using the CSM-CROPGRO-Dry bean model, in common bean cultivars with contrasting growth habits. Additionally, the potential application of spectral indices (NDVI and chlorophyll index - LCI) to forecast the yield of common bean cultivars was evaluated. The cultivars IAC Imperador (determinate growth and early cycle) and IPR Campos Gerais (indeterminate growth and normal cycle) were used in this study. These cultivars were subjected to five irrigation levels (54%, 70%, 77%, 100%, and 132% of crop evapotranspiration). Water deficit reduced the common bean agronomic performance, regardless of the cultivar. Furthermore, the water deficit reduced the technological and nutritional quality of the grains and the accumulation of macronutrients and anticipated the maximum daily demand for most macronutrients. IPR Campos Gerais showed better agronomic performance, efficiency, and response to water use than IAC Imperador, in addition to higher technological and nutritional quality and greater accumulation of biomass and macronutrients. Moreover, the maximum daily nutrient demand of cultivar IAC was anticipated compared with that of IPR. The CSM-CROPGRO-dry bean model showed high accuracy in estimating the growth and yield of the evaluated cultivars. Based on the long-term analysis in the model, it was observed that it is possible to manage irrigation with a controlled water deficit without significantly reducing the common bean yield if sowing is anticipated (March-April) within the winter crop. The meteorological element that most interfered with common bean yield was the global solar radiation (GSR) after the flowering of the crop, in which each unit increment in the GSR generated increments in the grain yield (GY) of the cultivars IAC and IPR by 55 and 50 kg ha-1, respectively. It was possible to forecast the GY of common bean cultivars (R2 = 0.64; RMSE= 370 kg ha-1; MBE= -140 kg ha-1) from the NDVI, both in individual models by cultivar and in the general model, whereas for the LCI, the accuracy was lower (R2 < 0.40; RMSE > 650 kg ha-1; MBE > 450 kg ha-1). These results demonstrate that the definition of more specific management is essential to increase sustainability in areas cultivated with common bean, helping to optimize the use of water and nutrients, sowing dates, and the application of remote sensing in cultivars with contrasting growth habits.