[Temporal and spatial variation of water requirement of winter wheat and its influencing factors in Henan Province, China].

Based on mean meteorological data of ten days in 17 observation stations from 1961 to 2012, the reference crop evapotranspiration was computed using Penman-Monteith formula recommended by FAO. The water requirement of winter wheat in Henan Province was calculated by adopting crop coefficients and the growth stage of winter wheat from the "National Irrigation Experiment Database", and the temporal and spatial distribution, variation and affecting factors in recent 51 years were analyzed by means of time-series analysis and gray relational grade analysis. The results showed that the average water requirement of winter wheat was 345-492 mm in Henan Province from 1961 to 2011, and it was lowest at Lushi station and highest at Mengjin station.

[Effects of girdling on growth, yield and water use efficiency of cotton].

An experiment with girdling applied on the main stem and fruit branch during the early or flourishing stage of flowering and boll-setting was conducted to investigate the effects of different girdling treatments on the growth, yield and water use efficiency (WUE) of cotton. The results showed that compared with the control (CK), leaf area index (LAI) of girdling treatments reduced significantly and the maximum LAI of girdled cotton occurred 5-15 days in advance. Girdling reduced the shedding rate of squares and bolls significantly, and the shedding rate of squares and bolls with girdling applied on the main stem at the flourishing stage was 15.

[Light environment characteristics in maize-soybean strip intercropping system].

Observations on the light environment characteristics in maize-soybean narrow stnp intercropping system were made in 2006 and 2007 to study the spatial distribution of photosynthetically active radiation (PAR) in intercropped crop canopy, and to analyze the effects of light environment on crop biomass. The results indicated that in early growth period, the light transmittance at the bottom of the edge rows of soybean strips adjacent to maize was higher than that of the inner rows of soybean strips, while it was in adverse for maize strips. The horizontal variation of light transmittance at the bottom of crop canopy did not vary significantly at reproductive stage, and the average light transmittance was less than 7%.