Crescimento, desenvolvimento e rentabilidade do algodoeiro BRS 200 - Marrom, irrigado.

Abstract

A field experiment was carried out at the Embrapa's Experimental Station of Barbalha-CE (7°19' S; 39°18'W and 415,74m high) during the growing season of 2005 with the objective of investigating the effect of different water depth on BRS 200 Marron cotton cultivar (Gossypium hirsutum L). The treatment were: Ti - 0.8; T2 - 0.1.0 and T3 - 1.2 of the crop transpiration, estimated by the Bowen ratio-energy balance method, corresponding to the following irrigation water depths of 411.6 mm; 514.5mm and 617.4mm. It was evaluated cotton yield, some crop components (fiber percent, boll weight, weight of 100 seeds) and tecnologial characteristics of cotton fiber. It was also estimated the water use efficiency and the economic efficiency of the production system. It was also computed plant height, stem diameter, leaf area and total phytomass. The most expressive results were: cotton yield increased with increasing irrigation water depth, the highest water depth (617.4mm) produced 3.289.5 kg ha "1 of cotton. The irrigation water depth did not affect the yield the yield components (fiber percent, boll weight, 100 seeds weight and fiber technological characteristics of the BRS 200 - Marram cotton cultivar). The water use efficiency decreased from 0.602; 0.554 and 0.533 kg m"3, with the application of 411.6; 515.5 and 617.4 mm, respectively. All the treatments showed economical return with net income per hectare of R$ 386.99; R$ 732,89 and R$ 1,140.37 to the treatments which received the water irrigation of 411.6; 515.5 and 617.4 mm, respectively, with a benefit/cost ratio of 1.59; 1.83 and 2,12, based in the prices practiced. It observed also significant differences for all the growth variables studied, but the treatment which received water irrigation of 617.4 mm shower the best result throughout the crop growth cycle.