花后小麦叶面积指数与光合和产量关系的研究

Effects of leaf area index on photosynthesis and yield of winter wheat after anthesis

以大穗型品种泰农18(T18)和中穗型品种山农15(S15)为材料,采用裂区设计,主区设置180 kg/hm2和240kg/hm2两个氮肥水平(纯氮),裂区设置75×104株/hm2,150×104株/hm2和225×104株/hm2三个种植密度,研究了叶面积指数与冬小麦光合和产量的关系。结果表明:冬小麦下部叶片叶面积指数(LLAI,倒4叶和倒5叶之和)与群体净光合速率(CAP)和产量呈极显著的正相关关系;从开花到花后14 d之前,上部叶片叶面积指数(TLAI,旗叶、倒2叶和倒3叶之和)和全部叶面积指数(WLAI,下部叶片和上部叶片之和)与群体净光合速率(CAP)和产量并不呈必然的显著正相关关系(T18显著正相关,S15相关不显著),但花后14d至成熟期,两个品种的TLAI和WLAI均与群体净光合速率(CAP)和产量呈显著的正相关关系。氮肥水平和种植密度对产量存在显著的互作效应,无论是大穗型品种T18还是中穗型品种S15都可以通过适当增加密度(T18以225×104株/hm2为宜,S15以150×104株/hm2为宜),降低氮肥用量(180 kg/hm2)实现高产。

Leaf is the main tissue of photosynthesis for green plant. Leaf area is closely correlated with the grain yield of crops. To make clear the effects of leaf area index on photosynthesis and yield of winter wheat after anthe- sis, and to provide a theoretical basis for winter wheat cultivation with high and stable grain yield, Tainongl8 （T18）, a winter wheat cultivar with multi-grain number per spike, and Shannongl5 （S15）, a winter wheat cuhi- var with middle grain number per spike, were used as experimental materials. The two cuhivars were both widely grown. Field trials were carried out from 2008 to 2010 in two successive growth seasons in a split plot design, with 2 nitrogen rates （ 180 kg/ha and 240 kg/ha of pure nitrogen） being in the main plot and 3 plant densities （0.75, 1.50 and 2.25 million basic seedlings per hectare） representing in the subplots. The results showed that lower leaf area index （ LLAI, the third leaves and the forth leaves under the flag leaves on the stems） is positively and signifi- cantly correlated with canopy apparent photosynthesis （CAP） and grain yields during the lower leaf stay-green stage, and the top leaf area index （TLAI, flag leaves, the first leaves and the second leaves under the flag leaves on the stems） and whole leaf area index （WLAI） which consists of all of the leaves on the stems are positively sig- nificantly correlated with CAP and grain yield for T18 but not for S15 so the relationships are not certain within 14 days after anthesis. TLAI and WLAI are positively and significantly correlated with CAP and grain yields for two kind of wheat from 14 days after anthesis to maturity. There is a significant interaction between nitrogen rate and plant density on grain yield. Being reducing nitrogen amount from 240 kg/ha to 180 kg/ha of pure nitrogen, both T18 which adopts 2.25 million basic seedlings per hectare and S15 which adopts 1.50 million basic seedlings perhectare could gain high grain yields.