BIOMASS PRODUCTION AND DISTRIBUTION EFFICIENCY OF EARLY COTTON VARIETIES

Abstract

The plant growth analysis technique was used to assess the dry matter production , and the dry matter distribution between vegetative and reproductive structures of three early (CIAN Precoz, CIAN Precoz 2, CIAN Precoz 3) and a late (Deltapine 80) cotton varieties. A complete randomized blocks experimental design with three replications was used. Five destructive samples were taken at 71, 85, 99, 113 and 129 days after sowing (das). Plant height, number of nodes, stem diameter, plant leaf area, total dry weight, and dry weight of the vegetative and reproductive organs from three plants by plot were measured at each sampling date. Total dry weigth and leaf area data were used to estimate crop growth rate (CGR) , net assimilation rate (NAR), leaf area index (LAI), leaf area ratio (LAR), specific leaf area (SLA), and leaf weight ratio (LWR). Total dry matter, dry matter partitioning CGR, NAR, and LAI data showed that early varieties were photosynthetically more efficient and productive than the late variety Deltapine 80. LAR, SLA and LWR data were used to estimate varieties leafiness and leaf thickness. Data showed that as leafiness increased, leaf thickness decreased. Regarding leafiness, these varieties were ranked in an increasing order as: CIAN Precoz 3, CIAN Precoz, CIAN Precoz 2 and Deltapine 80.