Cotton Development Under Growth Regulator Management, Row Spacing and Plant Population.

The cotton cultivation presents itself as one of the most important and profitable activities related to agribusiness in Brazil. The use of high plant densities coupled with the use of growth regulator is an alternative to increase lint production per area, reduction in crop cycle, uniformity of reproductive structures, reduction of the cost of insects and weeds control. This research was conducted out at the experimental station of the São Paulo State University - UNESP, located in the northwest of São Paulo State-Brazil, during the growing seasons of 2010/2011 and 2011/2012, with the following factors: 1- Growth Regulator (1000ml / ha) applied 50 and 70 days after emergence and 20; 30; 40; 50; 60 and 70 days after emergence, 2- spacing (0.38; 0.45; 0.76 and 0.90 m) and 3-plant densities (6; 8; 10:13 plants / m). The experimental design was the randomized completely blocks in the factorial system 4x4x2 , with four replications, using the cotton cultivar FMT 701 , growing in a dark red latossol. The objective of this study was to evaluate the effect of growth regulator application systems, row spacings and plant densities on the growth and development of cotton in two growing seasons. The plant height, number of nodes , stem diameter, length of branches, number of reproductive structures in the fifth, seventh, ninth and eleventh reproductive branches and yield were evaluated during the growing seasons. The row spacings affected the vegetative characteristics of cotton plants and yield, thus the use of 0.45 and 0.90 m showed the highest yield of cotton lint. The application of growth regulator in six portions provided the lower values of plant height and number of nodes in the main stem.