[Ecophysiological characteristics and productivity of wheat-cotton community].

The eco-physiology and productivity of 6-2-2 wheat-early maturing cotton-middle maturing cotton were studied in comparison with traditional 6-2 wheat-middel maturing cotton. The results showed that after wheat harvested, the LAI of cotton increased fast, the leaf area duration(LAD) and CGR were raised obviously, the dry matter rose rapidly, and the accumulated amount was larger than CK. Light use efficiency was 1.13%, 21% more than CK. The effective blossom period was extended 18 d, and the lint yield in both 1998 and 1999 was over 2250 kg.hm-2, 21-22% more than CK.

[Ecophysiological effects of multiple cropping of winter wheat-spring corn-summer corn in Huanghuaihai Plain].

Compared to sequential cropping of winter wheat-summer corn and mono cropping of spring corn, the ecophysiological effects of multiple cropping of winter wheat-spring corn-summer corn in Huanghuaihai Plain were studied. The results showed that under the multi-cropping, the crops occupied higher spatial niches during the period of reproductive growth. Ecological factors such as light, temperature, and air were improved, and plane light acceptance was changed into multistory light acceptance, which made the relative intensity of illumination in crop communities increased. Moreover, soil temperature between rows and wind velocity in planting strips were also increased. All these changes were advantageous to increasing the intensity and velocity of grain filling. The chlorophyll content and photosynthetic rate in functional leaves of crops were higher, which was the main reason of yield increase under multiple cropping.