Actual impacts of global warming on winter wheat yield in Eastern Himalayas

Himalayas, are among the areas most vulnerable to global warming, however, little is known about warming impacts on the crops. Therefore, the actual affects of anticipated warming on winter wheat were tested in Tibet, China. During the period 1988-2012, Tibet region has experienced a large increase in daily mean, minimum and maximum temperatures during wheat growing seasons by 0.50, 0.67 and 0.51 oC every ten years, respectively. The de-trended wheat yield increased by 34.4 kg ha-1 year-1 during this period. According to the historical data, 1 oC increase in daily mean temperature could get 370.6 kg ha?1 gain in wheat yield. Similar gains in wheat yield were found in a field warming experiment with an increase of 1.1 oC in daily mean temperature. The field warming caused a significant reduction in the pre-anthesis phase and entire growth period by 14 and 13 days, respectively. The green leaf areas and spike number in the warmed plots were significantly higher than that in non-warmed plots, while the grain number per spike was significantly lower in the former than the later (P < 0.05). The main mechanism underlying the positive affects of this moderate warming on wheat yield is through improving plant development and growth during the pre-anthesis phase by mitigating the low temperature limitation. This study suggests that further efforts should be directed towards the improvement on agriculture infrastructure to utilize the positive affects of climatic warming on crop production.