TEMPORAL VARIABILITY OF PLUVIAL PRECIPITATION AND YIELD OF HERBACEOUS COTTON IN DIFFERENT SYSTEMS OF SOIL MANAGEMENT AND NITROGEN FERTILIZATION

Abstract

In order to analyze the effects caused by rain temporal variability on development of herbaceous cotton as a function of nitrogen fertilization and soil management system, experiments were carried out during four years in Alagoinha, Paraíba State, Brazil (1995, 1996, 1997, and 1999). It was used the cultivar CNPA 7H sowed in bed pits and in beds covered with plastic under four rates of nitrogen (0 kg ha-1, 30 kg ha-1, 60 kg ha-1 and 90 kg ha-1) in radomized blocks with three replications. Crop phenological stages, biomass accumulation, and yield and its components were analyzed. The annual rainfall average in the period was 1,028 mm with large variation in the total amount of precipitation among the years evaluated, and its distribution in each year. It is clearly obseved the rainy period from March through August. The vegetative and reproductive stages of the crop changed according to the rain distribution during the cottondevelopment phases. There was a large variation among soil management systems and nitrogen doses as a function of time.

KEY-WORDS: Gossypium hirsutum L.; fertilization; phenological stage; biomass.