Impacts of climate change on growth and yield of winter wheat in the semi-humid region of the Loess Plateau

Winter wheat growth and meteorological observation data in a semi-humid region of the Loess Plateau are used to analyze the effects of climatic change on winter wheat growth,and the relationship between ear dry weight growth of winter wheat and meteorological conditions.Results show that the interannual trend of precipitation in the study region fluctuated,and was a minimum in the 1990s.An interannual periodic change of 3 a and 8 a was observed.The interannual temperature trend was upward,and a linear fit of this trend produced a rate of 0.325 ℃/10 a.The crop aridity index during the growing season showed a marked upward trend,with a linear fit giving a rate 0.069/10 a.There was a significant drying and warming tendency from the beginning of the 1990s through 2010.Because of climate warming,the sowing time of winter wheat would be postponed by 2—3 d/10 a.Reviving time would advance by 4—5 d/10 a,and flowering and maturing times by 5—6 d/10 a.Overwintering days would be reduced by 5—6 d/10 a,and the entire growth period would shorten by 7—8 d/10 a.Growth speed of ear dry weight was much greater on the 83rd day after reviving,and then reverted to a slow speed on the 101st day after reviving.The highest ear dry material speed was on the 87th day after reviving.Because of climate warming,the amount of heat was abundant in most of the winter wheat growing period.The yield was very sensitive to climate change during the period between sowing and just before winter,as well as between the jointing and flowering stages.Every 1 ℃ increment in average temperature per ten days could decrease the yield of winter wheat by 10—15 g/m2.Sensitive periods are 20—25 d and 30—40 d.The precipitation influence and heat functions showed an opposite phase.except for the maturation stage,precipitation was positively correlated with yield.Yield was also very sensitive to precipitation change during the seeding and reviving-jointing stages.Every 1 mm increment in precipitation per ten days would increase yield by 15—20 g/m2.Sensitive periods are 20—25 d and 50—60 d.Abundant solar illumination during the overwintering stage would improve cold resistance training,and it had a strongly positive effect on yield during the postulation period.Every 1 h increment in sunshine duration per ten days would augment yield by 5—10 g/m2.The sensitive period is 25—35 d.Long sunshine duration would aid the accumulation of dry materials.