Substrate moisture and temperature in Cajanus cajan (L.) Millspaugh germination

Abstract

Cajanus cajan (L.) Millspaugh, a member of the Fabaceae, is commonly known as feijão-guandu. It was introduced into Brazil because it readily adapts to local climate conditions and tolerates a wide range of water and mineral nutrient levels. The objective of this study was to determine the substrate temperatures and water volumes that are conducive to feijão-guandu seed germination and seedling vigor. The experiment was conducted at the Laboratory of Seed Analysis of the Centre of Agricultural Sciences, Federal University of Paraíba, Areia, PB, Brazil. Seed germination was tested using paper towel rolls moistened with volumes of water equivalent to 2, 2.5, 3, 3.5, and 4 times the dry mass of the substrate. Variable temperatures in the range of 20 °C to 30 °C and constant temperatures of 25 °C, 30 °C, and 35 °C were used. The experimental design was completely randomized. The variables analyzed were water content, percent germination, first germination count, germination rate index, and seedling root and shoot lengths and dry weights. Increasing the volume of water used to moisten the substrate hindered feijão-guandu germination at all temperatures. It was determined that moistening the substrate with water volumes equivalent to 2.8 and 3.5 times the substrate dry weight at 30 °C and 35 °C, respectively, were the ideal conditions for evaluating feijão-guandu seed germination and seedling vigor. Key words: Feijão-guandu. Water volumes. Germination tests. ResumoCajanus cajan (L.) Millspaugh, popularmente conhecido como feijão-guandu é uma Fabaceae que foi introduzida no Brasil por ser uma cultura de fácil adaptação às condições climáticas do país e pouco exigente em água e nutrientes minerais. Dessa forma o objetivo foi determinar o volume de água para umedecimento do substrato e temperatura adequados para testes de germinação e vigor de sementes de feijão-guandu. O trabalho foi realizado no Laboratório de Análise de Sementes, do Centro de Ciências Agrárias, da Universidade Federal da Paraíba, em Areia -PB. As sementes foram submetidas ao teste de germinação em papel-toalha, organizado na forma de rolos e umedecido com volumes de água equivalentes a 2,0; 2,5; 3,0; 3,5 e 4,0 vezes a massa do substrato seco, nas temperaturas de 20-30