Pod Harvest Index Research Articles

Reação de genótipos de soja ao alumínio em hidroponia e no solo

O objetivo deste trabalho foi avaliar os genótipos de soja BR86-5974, BR86-7396, Dourados, Doko RC, EMGOPA 305, IAC-9, BR-9 (Savana), UFV-1, UFV-9 e UFV Araguaia em relação à tolerância ao alumínio (Al) em hidroponia e em solo. Na solução com Al foi medido o comprimento radicular. Em solo com 49% de saturação de Al avaliou-se área foliar, altura de planta, altura de inserção da primeira vagem, produção de matéria seca, produção de grãos e índice de colheita. Os genótipos BR86-7396 e IAC-9 são os de maior tolerância ao Al, e UFV-1 mostrou o pior desempenho. Houve correlação significativa entre alongamento radicular e produção de grãos (r = 0,705), área foliar (r = 0,645) e produção de matéria seca (r = 0,634). Isto indica que experimentos em hidroponia e solo são igualmente eficientes na seleção de soja tolerante ao alumínio. A variabilidade detectada sugere que o conjunto de genótipos de soja possui ampla variabilidade genética, o que é desejável em programas de melhoramento com o objetivo de elevar estabilidade de produção no Cerrado.

Effects of plant population density and cultivar on growth, yield and yield components in groundnut (Arachis hypogaea 1.)

An experiment was conducted at the University of Queensland Redland bay Farm (27°37′ S, 153°17′ E) in southeast Queensland, Australia to study response of groundnut cultivars [Improved Virginia Bunch, NC-7, Q18801 (Virginia types), TMV-2, McCubbin and Red Spanish (Spanish types)] to different plant population densities (6.3, 11.1, 25.0 and 100.0) arranged in square spacings. The objective was to study plant physiological and morphological characteristics associated with the optimum plant population density among groundnut cul- tivars. Leaf area index (LAI), interception of photosynthetically active radiation (PAR), total dry mass (TDM), dry mass (DM) partitioning, economic yield and yield components were measured. The results show that TDM and economic yield were both maximized at 25 plants m−2 in all cultivars and so were the radiation use efficiency (Ec), crop growth rate (CGR) and DM partitioning'toTeproductive components (pods and kernels). Overall, variation in economic yield (kernel DM) was determined by pod harvest index (HI), kernel HI, ratio of pod to peg plus pod number, kernel number per pod and kernel size. Most of these components were maximized at the optimum plant population density.

Micronutrients

Treatment of pigeonpea seed with cobalt nitrate (500 tug kg‐1 seed) increased plant height, number of branches, leaves, total dry matter, and yield. The chlorophyll content, crop growth rate, relative growth rate, and net assimilation rate also increased significantly. Peanut seed treatment with cobalt nitrate (500 mg kg‐1 seed) followed by two foliar sprays before and after flowering (500 mg L‐1 water) increased plant height, leaf number and total dry matter. Pod yield, shelling percentage, test weight and harvest index increased significantly. In both crops nodule number and leghaemoglobin content also increased. Seed inoculation with rhizobium alone was not sufficient to reach maximum yield in both crops grown on the soil tested. Cobalt apparently improves nitrogen fixation by rhizobium, resulting in higher yield.