中文摘要：

气候变暖对青藏高原农作物物候和生物量的影响存在着不确定性。基于2015年4月布设在西藏自治区拉萨市达孜县的一个玉米模拟增温试验,通过对玉米不同物候期（即出苗期、三叶期、五叶期、拔节期、灌浆期、乳熟期和成熟期）、地上生物量和株高的观测,分析了温度升高对玉米各个物候期和生长发育的影响。结果表明,试验增温使得每个样方的三叶期和五叶期都提前了2 d,拔节期平均提前了1.3 d（t=2.00,P=0.184）,灌浆期平均提前了3.3 d（t=2.00,P=0.184）,乳熟期平均提前了4.7 d（t=2.80,P=0.119）,成熟期平均提前了6.7 d（t=3.78,P=0.050 2）。增温使得出苗期—成熟期的间隔缩短了6.7 d（t=2.77,P=0.050 2）,使得灌浆期—成熟期的间隔缩短了3.3 d（t=2.43,P=0.122）。试验增温显著增加了播种期—出苗期的积温（t=11.21,P=0.000）,增加11.89℃;显著减少了出苗期—三叶期间的积温（t=77.55,P=0.000）,减少7.58℃;对三叶期—五叶期、五叶期—拔节期、拔节期—灌浆期、灌浆期—乳熟期、乳熟期—成熟期、以及播种期—成熟期的积温都无显著影响。试验增温对地上生物量和株高均无显著影响。

英文摘要：

There remains uncertainty on effects of climatic warming on crop phenology and biomass on the Tibetan Plateau. A field warming experiment was conducted in a maize system located at the Dazi county of the Tibet since late April, 2015. This study examined the effect of warming on maize phenology （i.e. sowing time, seeding stage, trefoil stage, five-leaf stage, jointing stage, pustulation period, milk-ripe stage, mature period）, aboveground biomass and plant height. The trefoil stage and five-leaf stage completed 2 days earlier; the jointing stage completed 1.3 days earlier （t=2.00, P=0.184）, the pustulation period completed 3.3 days earlier （t=2.00, P=0.184）, the milk-ripe stage completed 4.7 days earlier （t=2.80, P=0.119）, and the mature period completed 6.7 days earlier （t=3.78, P=0.0502） under experimental warming conditions. Experimetal warming shorten 6.7 days of the interval between seeding stage and mature period （t=2.77, P=0.0502）, and 3.3 days of the interval between pustulation period and mature period （t=2.43, P=0.122）. Experimental warming increased cumulative temperature by 11.89 ℃ during the period from sowing time to seeding stage （t=11.21, P=0.000）, decreased cumulative temperature by 7.58 ℃ during the period from seeding stage to trefoil stage （t=77.55, P=0.000）. However, experimental warming had no obvious effects on cumulative temperature during the period from trefoil stage to five-leaf stage, from five-leaf stage to jointing stage, from jointing stage to pustulation period, from pustulation period to milk-ripe stage, from milk-ripe stage to mature stage, and from sowing stage to mature stage. Experimental warming had no significant effects on aboveground plant biomass and plant height. Therefore, warming may alter maize phenology but did not significantly affect aboveground plant biomass.