Comportamento fisiológico e morfológico da cultura do algodão herbáceo (Gossypium hirsutum r. latifolium) irrigada nas condições semiáridas do Nordeste brasileiro.

Abstract

The field experiment was conducted in the Experimental Station of the Rio Grande do Norte Agricultural Research Company (EMPARN), at Ipanguassu-RN. The objective of this study was to analyse the morphological and physiological behavior of the cotton (Gossypium hirsutum r. latifolium) crop well watered and stressed, grows in the North-East of Brazil semi-arid region. The experimental treatment included two parcels: a non stressed (PI) and a stressed treatments. The physiological parameters analysed were canopy stomatal resistance, biomass, crop heigth, leaf area index and crop productivity. The behavior of the morphological (crop heigth, leaf area index and green and dry weights) and physiological (stomatal resistance, transpiration rate and leaf temperature) startered been observed in the 35th day after emergence. The crop physiological behavior was observed with a dynamic equilibrium porometer (LI-1600 from LI-COR). The irrigation water amount applied in the stressed treatment (Pll) can may been the main cause for the observed differences in the morphological and pysiological parameters. The leaf temperature in the stressed treatment was significantly greater than that of the well watered one. When irrigation was applied after a situation of strong stress, the crop did not restored the standard values of transpiration, leaf temperature and stomatal conductance showed in a well watered condition. The productivity reduction observed in the stressed treatment, wich reached 18% of that of the non stressed one, was also a result of the irrigation scheduling and the water amount applied in the Pll treatment.