Phosphorus application strategies to improve cotton productivity under arid climatic conditions

Abstract

Field experiment was conducted at Research Farm of Central cotton Research Institute, Multan, Pakistan during the years 2008-2010, to evaluate the phosphorus application techniques for improving cotton productivity under the arid climatic conditions. The treatments consisted of two methods of phosphorus fertilizer application (band placement and fertigation) either applied as a full dose at pre-plant or in three splits i.e. at sowing, 30 and 45 days after planting of the crop. Phosphorus was applied @ 50 kg P2O5 ha-1 in the form of triple super phosphate. The design of the experiment was split plot (main: application method). The whole quantity of potassium and 1/3rd nitrogen was applied at sowing. The remaining quantity of nitrogen was applied at first flower and peak flowering phases. cotton cv. CIM-557 was used as a test crop. Standard production practices were followed during the season. Composite soil samples from plough layer (0-15cm) were collected before imposition of treatments. Seed cotton yield and its components differed significantly, due to both the method and time of P-application. Among the P-application methods, fertigation proved to be better by producing 15% more seed cotton yield than band placement of P. Similarly application of P in three splits, on an average, produced 9% more yield than the full dose applied at pre-plant. A comparison among the individual treatments revealed that the maximum seed cotton yield of 2152 kg ha-1 was produced where P-fertilizer was applied through fertigation in three split doses. Yield contributing parameters including number of bolls per plant and boll weight also remained higher where P was applied through fertigation in 3 splits. The application of P through fertigation in 3 splits resulted in the production of maximum number of fruiting positions and intact fruit per unit land area. Fruiting positions ranged from 340 to 396 m-2 and intact fruits from 94 to 130 m-2 in different treatments. Fruit shedding decreased in either of the application techniques and time of P-application. Fruit shedding ranged from 67.2 to 71.9 % in different treatments. Furthermore, fertigation of P in 3 splits proved to better than the other application techniques by maintaining more soil P-availability during the season, producing more dry matter yield, with high P concentration in different plant parts and concurrent increase in P-uptake by the cotton plant.