Aspectos fisiológicos e crescimento do algodoeiro ‘BRS topázio’ cultivado com águas salinas e adubação potássica

The objective of this work was to evaluate the physiological indexes and the growth of the colored cotton cv. BRS Topázio submitted to irrigation with water of different levels of salinities and fertilization with doses of potassium. The experiment was conducted in pots under greenhouse conditions, using a non-saline sandy-loam Eutrophic Regenerative Neosol. A randomized complete block design with 4 replications was used, and the treatments were distributed in a 4 x 4 factorial scheme, with four levels of electrical conductivity of the irrigation water -ECw (1.5, 3.0, 4.5 and 6.0 dS m-1) and four doses of potassium (50, 75, 100 and 125% of the recommendation), the dose of 100% corresponding to 150 mg K2O per kg-1 of soil. The effects of treatments on CO2 internal concentration (Ci), transpiration (E), stomatal conductance (gs), CO2 assimilation rate (A), water use efficiency (EiUA) and instant carboxylation (EICi), dry leaf phytomass (FSF), dry stem biomass (FSC), dry shoot biomass (FSA), specific leaf area (AFE) and in the period from 30 to 130 days, the rate of net assimilation (TAA). The gaseous exchanges and the dry matter of the leaf, the dry stem biomass and the dry matter of the aerial part of the colored cotton cv. BRS Topázio reduces markedly when submitted to ECw levels greater than 1.5 dS m-1. The specific leaf area and the net assimilation rate of the BRS Topázio cotton were not affected by the irrigation water with saline water. Potassium fertilization had no influence on the analyzed variables of the colored cotton. There was no interaction between irrigation water salinity versus potassium doses for the analyzed variables. Objetivou-se avaliar os índices fisiológicos e o crescimento do algodoeiro colorido cv. BRS Topázio submetido à irrigação com águas de diferentes níveis de salinidades e adubação com doses de potássio. O experimento foi conduzido em vasos sob condições de casa de vegetação, utilizando-se um Neossolo Regolítico Eutrófico de textura franco-arenoso não salino. Utilizaram-se o delineamento de blocos casualizados, com 4 repetições, cujos tratamentos foram distribuídos em esquema fatorial 4 x 4, sendo quatro níveis de condutividade elétrica da água de irrigação (CEa) (1,5; 3,0; 4,5 e 6,0 dS m-1) e quatro doses de potássio (50; 75; 100 e 125% da recomendação), sendo a dose de 100% correspondente a 150 mg K2O por kg-1 de solo. Avaliaram-se os efeitos dos tratamentos sobre a concentração interna de CO2 (Ci), transpiração (E), condu