增温对青藏高原冬小麦干物质积累转运及氮吸收利用的影响

Warming impacts on the dry matter accumulation,and translocation and nitrogen uptake and utilization of winter wheat on the Qinghai-Xizang Plateau

青藏高原是气候变化的敏感区,该区域作物生产受气候变暖的影响较大,但至今仍缺乏相关的田间实证研究。探讨青藏高原作物生长发育对气候变暖的响应特征,对该区域作物生产技术的创新具有重要意义。该研究以高产优质冬小麦(Triticum aestivum)品种‘山冬6号’为试验材料,在拉萨市农业科学研究所科研基地进行田间远红外增温试验,研究了日平均气温升高1.1℃对冬小麦物质分配和转运的影响。研究表明:增温处理下,播种至开花阶段群体水平的干物质积累速率、籽粒干物质分配比例和开花前贮藏同化物转运量对籽粒产量的贡献率分别比对照提高了27.5%、5.6%和68.6%,但是开花至成熟期群体水平的干物质积累速率和籽粒干物质分配量无显著差异;增温提高了冬小麦的氮积累能力,成熟期氮向籽粒的分配比例及开花期营养器官中贮存的氮向籽粒的转运率均高于对照处理,分别高6.0%和5.5%;与对照相比,增温处理的收获指数无显著差异,但籽粒产量、氮吸收效率、氮肥偏生产力和氮收获指数均显著高于对照。该试验预期升温1.1℃将促进高海拔地区冬小麦干物质向籽粒分配和转运,有利于冬小麦高产和氮高效利用。

Aims Global warming is expected to be the strongest in high altitude mountainous areas, which are more ecol- ogically fragile and economically marginalized. The Qinghai-Xizang Plateau is among such areas most vulnerable to global warming, and more than 80% of its population depends on subsistence agriculture. The aim of this study is to understand the impacts of warming on indigenous crop production, which can help to devise better strategies for crop adaptation and food security in this area. Methods A field warming experiment using a facility of free air temperature increase was conducted to simulate the predicted warming level in Caigongtang town, Lhasa City, China. The experiment consisting of two treatments （warmed and non-warmed） was performed using a completely random design with three replicates. An infrared heater （180 em in length and 20 cm in width） of 1 500 W was suspended 1.5 m above the ground in each warmed plot. In each non-warmed plot, a ＇dummy＇ heater of same dimensions was also suspended to mimic the shading effects. The warming treatment was performed from the sown date to the harvest date. We measured dry matter and nitrogen accumulation, partition and translocation of winter wheat （Triticum aestivum） using ＇Shandong 6＇ under warming and control treatments. Important findings Results showed that, with 1.1℃ increase in daily mean air temperature during winter wheat growing season, the dry matter accumulation rate at population level from sowing to anthesis stage, grain dry matter partition ratio and contribution of dry matter translocation amount to grain after anthesis were 27.5%, 5.6% and 68.6% higher, respectively, in the warmed plots than those in the non-warmed plots. Meanwhile, warming increased nitrogen accumulation rate at population level of winter wheat. Nitrogen distribution proportions in grain and nitrogen translocation efficiency from vegetative organs to grain after anthesis in the warmed treatment were 6.0% and 5.5% higher than those in the non-warmed treatment, respectively. Compared with non-warmed treatment, warming decreased harvest index by 3.1%, though the difference was not statistically significant. Grain yield, nitrogen uptake efficiency, nitrogen partial factor productivity and nitrogen harvest index were 8.1%, 20.8%, 8.1% and 6.0% higher, respectively, in the wanned plots than those in the non-warmed plots. In conclu- sion, an increase in daily mean air temperature of about 1.1 ~C can enhance plant growth during the pre-anthesis phase by mitigating the low temperature limitation, and accelerate dry matter and nitrogen partition and transloca- tion to the grain after anthesis in winter wheat. These results suggest that warming may benefit winter wheat pro- duction through increasing nitrogen use efficiency in high altitude areas.