The objective of this study was to evaluate different levels and modes of nitrogen application on the yield and physiological quality of the black-eyed or cow-pea. The work was carried out on the Pici Campus of the Federal University of Ceará. The plots were made up of six rows of 5m, spaced 0.5m apart, the available area consisting of the four central rows, disregarding 0.5m at either end. Seeding density was 12 seeds m-1. At this stage, productivity from the seeds was obtained. The physiological quality of the seeds was evaluated by means of the following tests: germination, first count, emergence of seedlings, rate of emergence and shoot dry mass. The treatments consisted of the absence of nitrogen fertilization and of fertilization with 15 and 30 kg ha-1 of nitrogen, both in the soil and on the surface. Averages were compared using the Tukey test at 5% probability. Nitrogen fertilization did not affect plant productivity, seed germination nor the variables of vigour: first count, percentage of emergence and shoot dry mass. Nitrogen fertilization however did affect the rate of emergence, with the highest values being obtained from the seeds derived from unfertilized plants, and from those fertilized with nitrogen in the soil, regardless of the depth. Nitrogen fertilization as used here does not interfere with plant yield or with the physiological quality of cow-pea seeds cv. canapuzinho.
Vigna unguiculata; productivity; germination; vigour
