Rainfall variability effects on rice productivity and groundwater table in Punjab
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Date
2016
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Punjab Agricultural University, Ludhiana
Abstract
A field experiment was conducted at the Research Farm, School of Climate Change and Agricultural Meteorology, PAU, Ludhiana during kharif 2015. The experiment consisted of six treatments, i.e. two cultivars of rice (PR 122 and PR 124), two dates of sowing ( 15th May and 30th May) and two methods of planting (Direct seeded and conventional).Treatments were replicated thrice as per factorial split plot design of experimentation. The micrometeorological data on photosynthetically active radiation (PAR), relative humidity and canopy temperature were recorded. The periodic biometric observations on leaf area index and total dry matter accumulation were recorded. The yield and yield contributing characteristics (number of effective tillers, number of grains/panicle, 1000-grain weight, grain yield, biomass yield etc) were recorded manually at harvesting. The PAR interception and canopy temperature was higher under direct seeded method than conventional method. Relative humidity was higher in conventional method as compared to direct seeded method. Dry matter accumulation and leaf area index were higher under direct seeded method as compared to conventional method. The grain yield was higher under conventional method (68.54 q/ha) as compared to direct seeded method (65.84 q/ha). The historical data of rainfall, rice yield and ground water table depth was collected for different locations of Punjab (Ludhiana, Ballowal Saunkhri, Faridkot and Bathinda) from 2001-2015. In general, rainfall was increasing at Ludhiana, Ballowal Saunkhri, Faridkot and decreasing at Bathinda. Drought indices were calculated. Positive rainfall deviations (when actual rainfall is more than normal) are associated with positive SPI (Standardized precipitation index) values indicating wetness and negative rainfall deviations (when actual rainfall is less than normal) are associated with negative SPI values indicating mild to severe drought. Relationships between groundwater table and rainfall indicated that continuous deficit rainfall years led to decline in groundwater table. Historical analysis of rice yield indicated that rainfall during grain-filling stage (especially first week of September) led to low yield.