Cotton row spacing and plant density cropping systems I. Effects on accumulation and partitioning of dry mass and LAI.

Increase of plant density with decreasing cotton row spacing has been suggested as an alternative strategy to optimize cotton profit. Although, the primary goal of this method is to reduce input cost, however, there is limited information about the agronomic and physiological aspects of these systems across the world cotton belt. In this task, three cultivation systems were studied in terms of narrow row high plant density (NRHPD; 48 cm and 32 plants/m(2)), narrow row low plant density (NRLPD; 48 cm and 16 plants/m(2)) and conventional row spacing (CR; 96 cm and 16 plants/m(2)). Effects of these systems on the accumulation and allocation of dry mass as well as on leaf area index (LAI) were examined at critical growth stages during two growing seasons. Independently of row spacing, system with high plant density (NRHPD) produced significantly (P <= 0.001) greater dry mass and leaf area index (LAI) compared to lower plant density systems, i.e. CR and NRLPD. These differences became more significant at stage of maximum dry mass and LAI. However, this system of NRHPD partitioned the same or less dry mass to reproductive growth than other systems. Also, significant (P <= 0.05) differences were measured between systems with the same plant density and different row spacing, thus total dry mass and LAI were significantly higher in NRLPD than in CR system.