부산대학교 도서관

We analyzed the spatial and temporal variations (40 years from 1974–75 to 2013–14 with an interval of four decades) in wheat yield as influenced by the three important potential determinants (climate, fertilizers and irrigation) in the three regions (North-west, Central and South-west) of Indian Punjab. Wheat productivity in Punjab has increased linearly at 60–64 kg ha-1 year-1. Although linear increase in productivity can be attributed to technological developments but large year-to-year oscillations depicted the effects of climatic variations. Mann–Kendall and Sen’s slope estimator statistical tests indicated that majority of the trends in maximum temperature and rainfall in different regions were not significant, but there was a significant increase in minimum temperature at 0.053 C year-1 in north-east, at 0.047 C year-1 in central and 0.044 C year-1 in south-west regions of Punjab. Step-wise regression was used to assess the relative influence of three determinants (climate, fertilizer and irrigation) on yield. Minimum temperature explained 44% of variability in yield. Out of the remaining 56% variability, 44% variability in wheat yield was explained by irrigation availability and 7% by fertilizer application. The spatial interpolation showed the decade-wise shift in area towards higher productivity, higher temperature and lower rainfall during the wheat growing season.