Physiological Maturity and Determination of the Harvest Time of Vigna unguiculata L. Walp.

Abstract

The maturation process of seeds is genetically controlled and involves an organized sequence of physiological changes from the fertilization until the complete independence from the plant. It is recommended that the harvest occurs in the ideal moment, this way the seeds can express their full potential, with maximum dry matter accumulation, reaching high potential of germination and vigor. The objective of this study was to determine the physiological maturity point of cowpea bean seeds (Vigna unguiculata L. Walp.), cv. Corujinha, aiming to indicate the best harvesting period, in order to guarantee greater germination potential and seed vigor. Cowpea pods were harvest from the third until the twenty-first day after anthesis, with intervals of three days between the harvests. After each harvest, the following evaluations were carried out: pod and seed color, number of seeds per pod, pod and seed biometry, pod and seed moisture, water content, germination, germination speed index, length and dry matter of the shoots and roots. At 15 DAA, the seeds and pods presented light green coloration, with maximum values of length, width, thickness, dry matter, germination percentage and germination speed index, at a vigor level. There was a gradual reduction of water content in the seeds and number of seeds up to 21 DAA. The highest values for shoot and root length were observed at 18 DAA, when seeds and pods showed light brown color and for shoot and root dry matter at 21 DAA, with brown color. The physiological maturity of cowpea seeds was rapid and occurred between 15 and 21 DAA. The harvest is recommended at 15 days after anthesis, when the seeds present high physiological quality.