Concentração, acumulação de P, K. Ca e Mg e crescimento da soja(Glycine max (L.) Merrill) em diferentes estadios de desenvolvimento

Abstract

This work was performed with the objective of studying the concentration^accumulation of P, K, Ca and Mg and plant grow th in various parts of the soybeans UFV-1 and UFV-4 cultivars , at diverse stages of development. The experimental work was conducted at Escola Superior de Agricultura de Lavras, Minas Gerais State, Brazil, at the beginning in greenhouse seeking better conditions for emergence, and 35 days after that it was exposed to the natural conditions, using samples of a very clayey Dusky Red Latosol (Typic Acrorthox) , from Deceiaber 1981 to May 1982. It was a completely randomiz ed blocks in a factorial design 2x7 with four replications .The various treatments in cluded two cultivars submit ed to seven periods of sampling (20, 40, 60, 80, 100, 120 e 140 days after germination) , using a variable number of plants . In these plants the fresh weight of the plant, dry matter production and the amounts of P, K, Ca and Mg weie evaluat ed . The results evidenced that themaximum amounts of fresh weight for the UFV-1 and UFV-4 cultivars respectively ocurred at 100 and 103 days, and the ones of dry matter, at 107 and 114 days,whereas the curves of the amounts of P, K, Ca and Mg in dry matter revealed a similar model to the those of dry matter production of diff erent parts of plant . The P, K, Ca and Mg concentrations vari ed as a function of development st ages of plant . Ca was more concentrai ed in the leaves and Mg in th e veg etative parts of plant, with decrea se of the amounts accumulated at the end of the growing season In general, the ouantities cf P in the grains are higher than those found in the other parts of plant, whiüe the K, Ca and Mg amounts are higher in the shoots and roots . In order to reach the maximum growth of the plant, the UFV-1 presented higher amounts of P, K, Ca and Mg than did UFV-4 . Both cultivars had maximum accumulation of nutrients at the following growing stages (days): P (88) ,K (82-86), Ca(108 - 116) and Mg (90-92), whereas maximum accumulated quantities were at the following limits (mg/plant) : P (4,49-5,53), K(30 , 56-43,0 5), Ca (57,46 - 59,53) and Mg (4,29 - 4,90). At the end of the grow ing season, th* accumulation of nutri erts in the UFV-1 and UFV-4 cultivars, was in the following order : K>Ca>P>Mg.