Impact of weighted rainfalls on the yield of wheat in the Punjab, Pakistan

A study of weighted rainfalls, which is almost unprecedented effort in agricultural statistics, was conducted to develop a mechanism to assign weights to different amounts of rainfalls proportional to their importance/need of time with reference to the crop condition. It is a methodology for determination of weights assigned to amounts of rainfalls of different months of Rabi season that have a significant impact on the yield of wheat crop. The data of rainfalls from 2000 - 2001 to 2006 - 2007 at seven observatories of Meteorological Department, Punjab and wheat production of respective districts were used. It was observed that as the rainfalls in the important months of Rabi season are increased; the average yield of wheat also increases. But at a certain level, excess rainfalls cause a decline in the yield. The suitable quadratic models were fitted independently between yield and amount of rainfalls for each month of the season. In each case explained variation R² was used as a proposed weight to the rainfall of the relevant Rabi month. The empirical study supported the use of weighted rainfalls instead of total rainfalls of Rabi season. The concept of weighted rainfall was also proved effective in estimating the crop production through a statistical model.