Yield Response Factor for Onion(Allium Cepa L) Crop Under Deficit Irrigation in Semiarid Tropics of Maharashtra

Download http://www.agriculturejournal.org/volume3number2/yield-response-factor-for-onion-allium-cepa-l-crop-under-deficit-irrigation-in-semiarid-tropics-of-maharashtra/ IntroductionOnion(Allium cepa L.)is one of the important vegetable crops commercially grown in India.India is the second largest producer of onion in the world, next only to China. The total area under onion in India is 1064000 ha and the total production is 15118000 MT. India accounts for 26.8 per cent the total area and 19.9 per cent the total production of the world. The average productivity of the world is 19.1 MT/ha while India being the second major onion producing country in the world has a productivity of 14.2 MT/ha (Source FAO Website: March 2012 and Indian Horticulture Database 2011). Maharashtrais the leading onion grower and producer state in the country which accounts 39 per cent of the total area and 32.5 per cent national production followed by Karnataka, Gujarat etc. The area under onion in Maharashtra is 415000 ha and theonion production is 4905000 MT. In India per hectare yield is highest in Gujarat (24.4 MT/ha) followed by Haryana (20.5 MT/ha), Bihar (20.3 MT/ha), Madhya Pradesh (17.5 MT/ha) whereas, in Maharashtra it is 11.8 MT/ha. (Source FAO Website: March 2012 and Indian Horticulture Database 2011).Abiotic stresses can directly or indirectly affect the physiological status of an organism by altering itsmetabolism, growth and development and adversely affect the agricultural productivity (Bartles and Sunkar 2005, Vibhuti et al 2015, Shahi et al 2015a). Water is the main limiting factor for production of many crops including onion in the arid and semiarid regions. Fresh and dry mass production of crop may reduce due to the adverse effect of water stress (Shahi et al 2015b). When water resources are scarce, deficit irrigation is one way of maximizing water use efficiency (Bekele and Tilahun 2007).Deficit irrigation is the practice of irrigating crops deliberately below their water requirements. Such practice is aimed at minimizing water applied to the crop so as to maximize crop yield per unit of water applied. This may however lower the yield per unit area. Many research works have been carried out to study the consequences of deficit irrigation on onion crop (Olalla et al., 1994; Gorantiwar and Smout.,2003; Pelter et al., 2004; Mermoud et al., 2005; Bekele and Tilahum, 2007; Ouda et al., 2010; and Pejić et al., 2011).A research gap in the region where onion is produced in Maharashtra is the knowledge of water requirement of the onion crop under deficit irrigation. Moreover, the consequences of deficit irrigation regimes are yet to be fully understood. Two key parameters commonly required in determining crop water requirement and predictions of yield-water response to deficit irrigation are crop coefficient (Kc) and yield response factor (Ky). The yield response factor (Ky)is ratio of relative yield reduction to relative evapotranspiration deficit. It is the factor that integrates the weather, crop and soil conditions that make crop yield less than its potential yield in the case of deficit evapotranspiration. The yield response factor Ky is commonly required as input data in some empirical water production functions like (Jensen, 1968) and (Stewart et al., 1977) to predict crop yield response to water.In order to determine the yield response factor of onion crop for Rahuri region (Maharashtra) the present study was carried out by raising the onion crop under different regimes of deficit irrigation approach. It is anticipated that the information generated in this study will be useful for developing crop water requirements for irrigated onion under deficit irrigation regimes and for the overall improvement of irrigation water management for onion in the study area.Materials and MethodsThe field experiment to determine the yield response factor of the onion(Allium cepa L.)cv. N-2-4-1 crop under the deficit irrigation approach was conducted during summer season of 2012 at Instructional Farm of the Department of Irrigation and Drainage Engineering, Dr. Annasaheb Shinde College of Agricultural Engineering, Mahatma Phule Krishi Vidyapeeth, Rahuri. Experiment was carried out in Randomized Block Design (RBD) with 27 treatments and two replications based on differentcombinations of the quantity of water stress days (no stress- (0.00S), 20% stress- (0.20S) and 40% stress- (0.40S) during different crop growth stages vegetative Stage (VS) – up to 50 days , bulb development stage (BDS) – 50 to 75 days and bulb enlargement stage (BES) – 75 to 100