Nutrient extraction and exportation by common bean

Abstract

Average common bean (Phaseolus vulgaris L.) yield in Brazil and in the world is still very low, around 1000 kg ha-1 . However, there are producers in Brazil with average yields above 4000 kg ha-1. Certainly, one of the major obstacles to increasing productivity is the expected lack of information about the nutritional requirement for growing the crop, as new cultivars are often launched, but without information on management. Typically, producers with high yields apply high doses of fertilizers, based on information transmitted over two decades ago for ancient cultivars that currently do not are more cultivated. Thus, the objectives of this work were: (i) to quantify the inheritance and export of nutrients, as well as the harvest index of modern and productive cultivars of common bean, belonging to different commercial groups and growth habits; (ii) to evaluate, through systematic review and meta-analysis, the latest studies on the export of nutrients (N), phosphorus (P) and potassium (K) per unit of bean grain produced, seeking to verify the difference between cultivars type I, II, III and IV. The study referring to objective (i) took place in Lavras - MG and was carried out in a randomized block experimental design with four replications, using eight common bean cultivars. To evaluate the accumulation and export of nutrients, plants were collected in the vegetative (V4, with 3, 5 and 7 trefoils) and reproductive (R5, R7, R8 and R9) stages. The accumulation of total dry mass and nutrients and at each phenological level were determined, as well as the productivity and export of nutrients by the grains. There were differences in the positioning of dry mass and nutrients between cultivars in the initial stages of development, but from R8 onwards verification was not verified. The initial growth and nutrient accumulation by the early TAA Gol and BRS FC104 cultivars was higher when compared to type II and III cultivars. K was exported in smaller quantities by the cultivars BRS Estilo, BRS FC104 and TAA Gol, compared to the other cultivars. When the growth types are contrasted, type II plants (BRS Estilo, VR20, Tuiuiú and BRSMG Uai) export more P, K, Mg and Zn than type I cultivars (BRS FC104 and TAA Gol). The systematic review (ii) indicates that the average exports of N, P and K per ton of bean grains were 32.7, 3.5 and 15.4 kg Mg 1 respectively. The average exports of N, Pa and K per hectare, considering the productivity treated in the studies of 2673 kg ha 1, was 77.6, 8.3 and 36.8 kg ha 1, respectively.