二氧化碳、施氮量和移栽密度对汕优63产量形成的影响--FACE研究

Effects of CO_2 Concentration, Nitrogen Supply and Transplanting Density on Yield Formation of Hybrid Rice Shanyou 63: A FACE Study

大气二氧化碳(CO2)浓度升高使水稻产量增加,但这种影响是否因不同栽培条件而异尚不清楚。2011年利用中国稻田FACE(Free Air CO2Enrichment)系统平台,以敏感水稻品种汕优63为供试材料,二氧化碳设环境CO2浓度(Ambient)和高CO2浓度(Ambient+200μmol·mol-1),施氮量设低氮(15 g·m-2)和高氮(25 g·m-2),移栽密度设低密度(16穴·m-2)和高密度(24穴·m-2),研究了不同栽培条件下大气CO2浓度升高对杂交水稻产量形成的影响。结果表明:高浓度CO2对水稻抽穗期和成熟期没有影响,但使结实期株高显著增高(+7%);使单位面积穗数(+8%)和每穗颖花数(+19%)明显增多,进而使单位面积颖花量大幅增加(+29%)。高浓度CO2条件下穗数增多主要与最高分蘖数明显增加有关,而分蘖成穗率显著下降;穗型增大主要由单茎干重而非单位干重形成的颖花数增加所致。高浓度CO2环境下水稻结实能力呈增加趋势,其中平均粒重的增幅达显著水平。大气CO2浓度升高使水稻籽粒产量平均增加36%,其中在低氮低密度、低氮高密度、高氮低密度和高氮高密度条件下分别增加43%、46%、34%、23%。增施氮肥或增加移栽密度使水稻产量略有下降,但均未达显著水平。以上结果表明,高浓度CO2环境下杂交水稻因库容量增大导致产量大幅增加,调整施氮水平和移栽密度可在一定程度上改变这种肥料效应。

Increasing atmospheric CO2 concentrations （[CO2]） generally increases yield of rice grains, but it is unctear whether such effect of elevated [CO2] is modified by cultivation practices. Under FACE conditions, a responsive euhivar Shanyou 63 was grown under two levels of [CO2] （ambient, ambient ＋200 μmol·mol-1）, two nitrogen rates （LN, 15 g· m-2; HN, 25 g· m-2）, and two transplanting densities （LD, 16 hill· m-2; HD, 24 hill· m-2）. The results showed that elevated[CO2] had no effects on phenologieal development, hut significantly increased plant height at grain filling stage（＋7% ）, as compared with ambient CO2. Under elevated[CO2], panicle number per unit area（ ＋8% ） and spikelet number per panicle （＋ 19% ） were increased, thus resulting in substantial increase in spikelet number per unit area（ ＋29% ）. The CO2-induced increase in panicle number per unit area was mainly due to an increase in maximum tiller number, while percentage of productive tillers reduced significantly. The enhanced panicle size in high[CO2] resulted from the increase in dry weight per stem rather than the ratio of spikelet number to stem weight. Elevated[CO2] significantly increased average grain weight. Increasing CO2 concentration increased rice grain yield by an average of 36%, being 43%, 46%, 34% and 23% for LNLD-, LNHD-, HNLD- and HNHD, respectively. These results indicate that the C02-induced increase in spikelet number per unit area results in substantial increase in grain yield of hybrid rice, which can be modulated by appropriate adjustment in nitrogen supply and transplanting density.