Cotton yield enhancement by application of growth promoters
By Ashfaq Ahmad, Muhammad Shaukat, Fahd Rasul,
Hafiz Salman Saeed and Syeda Refat Sultana
COTTON (Gossypiumhirsutum L.) is not only the fiber and cash crop of the Pakistan but also known as the 2nd best potential source for plant proteins after soybean and the 5th best oil-producing plant after soybean, palm-tree, colza and sunflower. It is regarded as white gold because it provides principal raw material for flourishing textile industry and also lint as an export item. Contribution of cotton in gross domestic product (GDP) and value addition in agriculture is 1.5 per cent and 7.0 per cent, respectively. Cotton was sown on an area of 2.88 million hectares during 2012-13. During the period (July-March) 2012-13, the production of 13.0 million bales was recorded (Govt. of Pakistan, 2013). But the average yield is much below than the required level as compared to the other developed countries like China, USA, etc. The low average national yield may be due to poor agronomic practices, such as the use of low quality seed resulting in poor germination which would raise less plant population, improper sowing date and method, use of fertilizers in unbalanced ways and weeds infestation.
Foliar spray of different botanicals enhanced total protein, chlorophyll contents, total soluble sugar and total phenolic contents of crop plant. Essential micronutrients like zinc, iron, manganese, copper, boron and magnesium are required for plant activities such as chlorophyll formation, photosynthesis, meristematic development, oil and protein synthesis, gossypol, tannin and phenolic compounds development. So, an experiment was conducted at Agronomic Research Area, University of Agriculture, Faisalabad, during the Kharif season of 2012. The purpose of this study was to maximize seed cotton yield by application of commercially or naturally available plant growth promoters in cotton-wheat cropping system under semi-arid conditions.
Five plant growth promoters (Moringa leaf extract, Polydol, Multisol, Classic and Asahi star) along with water spray and control were applied exogenously on cotton cv. MNH-886 with time interval of 30 days. Moringa leaf extract is a rich source of cytokine in and 3 per cent moringa leaf extract was used. Polydol (N2= 6 per cent,P2O5= 8 per cent andK2O= 6 per cent (w/w) r), Multisol (Fe= 2 per cent, Zn, B= 3 per cent and Cu, Mn= 1 per cent), Classic (Zn, B= 10 per cent) and Asahi star (P-Nitro phenol= 0.3 per cent, O- Nitro phenol= 0.5 per cent and 5- Nitro-phenol= 0.1 per cent) are synthetic plant growth promoters. Recommended dose of 500 ml/acre for each was applied.
Growth and yield parameters were recorded from each plot and analyzed statistically. The result indicates that maximum seed cotton yield (3558.2 kg ha-1) was obtained from plots of 23rd May sown which were sprayed with Polydol i.e. 30 per cent more yield as compared to control (2730.8 kg ha-1). Polydol was followed by Moringa Leaf Extract (MLE) produced 3304.7 kg ha-1seed cotton yield which is 21 per cent more than control. Similarly, maximum total dry matter (960.31 gm-2), maximum leaf area index (3.67) and maximum leaf area duration (305.25 days) were observed with application of MLE. However, the maximum ginning out turn (GOT) was noted in the case of Polydol. Ginning out turn (GOT) revealed that partitioning of accumulated dry matter was accelerated more by Polydol than other growth promoters. Chlorophyll is a pigment which absorbs visible spectrum (480-740 nm) of sun light.
The amount of chlorophyll produced by a plant is directly related with dry matter production. The maximum amount of chlorophyll was produced in the leaves of those plants which were sprayed with MLE. Membrane stability is a good indicator of stress enduring. So, a membrane leakage test was carried out to examine the membrane stability induced by growth promoting substances. No improvement in induction of membrane integrity was observed through plant growth promoters. Nevertheless, the minimum membrane leakage was noted in Asahi star sprayed plants. As this research was undertaken to provide a supplement in order to get maximum yield in cotton-wheat cropping system. Hence, it is recommended that seed cotton yield can be increased up to 21-30 per cent with foliar spray of MLE and Polydol. In the case of planting time, it is concluded that cv. MNH-886 should be sown before the end of May in order to get maximum cotton yield with application of growth promoters. There is a need of the hour to use plant growth promoters for cotton and other crops under different ecological conditions in order to maximize the outcomes.
The writers are associated with the Agro-Climatology Lab, Department of Agronomy, University of Agriculture, Faisalabad, Pakistan. They can be reached at <firstname.lastname@example.org>