Cotton Cultivars and Phosphorus Use Efficiency

Abstract

Pakistan is rich in calcareous soils. Though, in calcareous soils, cotton growth as well as production is highly adversely affected. Farmer community in the country is facing very serious problem of fertilizer costs, pest attack and marketing of their product. Traditional system of fertilizer use and the efficacy of general fertilizers has made it very difficult task to grow cotton in the hot environmental conditions of southern Punjab. Phosphorous deficit conditions result in low yield and higher shedding percentage besides the deficiency in the quality of fibre characteristics. The experiments were designed to supplement the crop nutrition to improve cotton productivity and to upgrade the phosphorous availability in the plants tissues. Foliar application of phosphorous using triple super phosphate as a source was used to enhance the vegetative growth, biochemical activity, improved the photosynthesis and chlorophyll contents of cotton plants. Two experiments were conducted in the field plots using Randomized Complete Block Design (RCBD) factorial with three replications and one experiment was conducted in pots using Randomized completely block design (CRD). In the 1st experiment, five different levels of phosphorus were applied to evaluate the cotton cultivars in pots to enhance the growth and productivity of cotton crop. Five levels of phosphorus used in pots were 0 kg ha-1, 25 kg ha-1, 50 kg ha-1, 75 kg ha-1 and 100 kg ha-1 while ten cotton cultivars were used such as that CIM- 598, CIM- 602, CIM- 616, CIM- 600, MNH- 886, MNH- 6070, FH- Lalazar, IUB- 2013, CIM- 573, and CIM- 612. In the experiment-II, four Phosphorous levels 0, 50, 100 and 150 kgha-1 were applied using triple super phosphate as a source and five cotton cultivars were CIM- 598, MNH - 886, CIM - 616, CIM - 612, and FH - LALAZAR to enhance phosphorous use efficiency in cotton crop. In the experiment-III, seven Phosphorous levels {(0, 50, 50+foliar (2%TSP solution), 75, 75+foliar (2%TSP solution), 100+ seed treatment kg ha-1 (5%TSP solution), 100+seed treatment (5%TSP solution) +foliar (2%TSPsolution)} kgha-1 P, respectively using triple super phosphate as a source. In this experiment we were be used three Cultivars MNH- 886, CIM- 616, FH- LALAZAR, to enhance phosphorous use efficiency in cotton crop. In the experiment-I application of phosphorous (100 kg ha-1) resulted in higher plant height, intermodal distance, vegetative weights, total dry matter, yield and fiber strength as compared to control treatments. In experiment-II, application of phosphorous at the rate of 150 kg ha-1 gave greater number of nodes plant height, intermodal distance, boll retention percentage, total dry matter, yield and chlorophyll contents as compared to their respective control treatments. In Experiment-III, foliar application of phosphorous with seed treatment

2 100+seed treatment (5% TSP solution) +foliar (2% TSP solution) gave higher results concerning boll retention percentage, total dry matter, yield, water use efficiency, staple length and chlorophyll contents as compared to their respective control treatments during the years 2015 and 2016.It is concluded from the research trials and their findings that foliar sprays of nutrients increases photosynthesis which improve water contents and plant vigour to cope with water deficit situation. Further the foliar supplement increases number of buds, number of bolls, yield per hectare and quality parameters of fiber in cotton.