前期干旱对春小麦叶面积、光合速率和可溶性糖含量的影响

EFFECTS OF SOIL DROUGHT FROM EMERGENCE TO JOINTING ON THE DYNAMIC CHANGE OF LEAF AREA,PHOTOSYNTHETIC RATE AND SOLUBLE SUGAR CONTENT IN SPRING WHEAT

在前期干旱条件下,叶面积减小,可溶性糖含量降低,但光合速率提高。叶面积与产量的相关明显高于光合速率与产量的相关。水肥条件对叶面积、光合速率、可溶性糖含量及产量均有明显影响。叶面积与施肥水平呈正相关;光合速率和可溶性糖含量与施肥水平呈负相关.在逆境条件下,植株具有较强的自动调节能力,但基因型间的自动调节能力和效应存在明显差异,提高肥力可以明显缓解前期干旱胁迫造成的不良影响.

Drought is the most serious problem reducing wheat yield among all of the natural fac- tors in Heilongjiang province.The studies(pot experiment)were carried out on the campus of the Northeast Agricultural College in 1987 and 1988.Two cultivars with different characteris- tics,Kefeng No.3 and Kehan No.7,were used.Fertilizer treatments(ratio of N to P=1:1.5):1)N_0P_0—no fertilizer,(CK);2)N_1P_1—pure N and P_2O_5150 kg·ha^(-1);3)N_2P_2— 300kg·ha^(-1).The drought treatment was carried out from emergence to jointing.The main aim of the study is to understand the effects of drought on yield,physiological metabolism and the different responses between the two cultivars. The results indicated that soil moisture and fertilizer level could significantly have effects on leaf area,photosynthetic rate,soluble sugar content and yield(both Ye and Yb).The cor- relation between leaf area and fertilizer was positive,but negative between photosynthetic rate,soluble sugar content and fertilizer.Photosynthetic rates increased along with the leaf area and the soluble sugar content decreased under the drought condition.The correlation coefficients between leaf area,economic yield and biological yield(0.8963* * and 0.6223 *, respectively)were much higher than those between the photosynthetic rates and economic yield as well as biological yield(-0.4829 and -0.1822,respectively).Therefore,yield is mainly dependent upon green leaf area,not the photosynthetic rates.The raising of photosynthetic rates is only a kind of autoregulating ability in wheat plant under adverse condition. Under the experimental conditions,Kehan No.7 was much more drought-resistant than Kefeng No.3.The drought-resistant ability in wheat plant was contrary with the changing range of soluble sugar content.Besides,the experimental results showed that there was a close correlationship between photosynthetic rates and soluble sugar content under the same mois- ture condition(drought,r=0.8414 *;normal moisture,r=0.8305 *).Therefore,in the exper- iment,the increase of photosynthetic rates was one of the causes of raising the sugar content in wheat plant.