Research On The Relationships Between Planting Patterns And Water Use Efficiency In Winter Wheat And Summer Soybean

The field experiment was conducted in agronomy experimental station of Shandong Agricultural University using different types of crop, which were the winter wheat and the summer soybean as experimental materials in 2007-2009 growing seasons. The objective of this paper was to investigate the effect and value in production of planting patterns on water utilization. Under the same plant population (3.09x10⁵ plant hm^-2), the summer soybean experiment consisted of five planting patterns by adjusting the row spacing (cm)×plant spacing(cm),which were 18 cm×18 cm (A), 27 cm×12 cm (B), 36 cm×9 cm (C), 45 cm×7.2 cm (D), 54 cm×6 cm (E) respectively. The winter wheat experiment was composed of three planting patterns under the same plant density (1.8×10⁶ plant hm^-2), containing uniform (25 cm) row, wild (40 cm) + narrow (20 cm) row for flat planting pattern and furrow planting. Each planting pattern had three irrigation treatments at jointing, heading and filling stages respectively, and the amount of irrigation was 30 mm, 45 mm and 60 mm every time. These results indicated that planting patterns could significantly affect the crop yield and water use efficiency (WUE), improve the dynamics of population development, physiological and ecological characteristics and water consumption rules effectively. The detailed results were as follows:1. Effects of planting patterns on dynamics of population developmentThe leaf area index (LAI) and total dry matter accumulation of A and B treatments were higher than those of E treatment by 30% and 25%,20% and 19% respectively in summer soybean. The weight of pod and pod of branch in treatments A, B and C were significant higher than those in treatment E, while there was no significant difference between D and E treatments.In winter wheat experiment, the difference of the population tiller number among planting patterns became narrower with the advance of development, so there was no significant difference in planting patterns at maturity stage, consequently. The LAI and dry matter accumulation of furrow planting were 13.49% and 9.82% significantly higher than those of uniform (25 cm) row. Irrigation played an important role in population development dynamics. The number of tiller, LAI, and total dry matter accumulation were raised with the increase of irrigation amounts.2. Effects of planting patterns on farmland microclimateThe furrow planting raised the photosynthetically active radiation (PAR) reflection ratio, penetration ratio and increased light capture ratio in 0-40 cm. Meanwhile, furrow planting increased the LAI, improve the total dry matter accumulation and thus significantly enhanced the Radiation Use Efficiency (RUE). Irrigation could further improve the farmland microclimate conditions near the ground, it not only increased the crop RUE significantly, but also reduces air relative humidity in plants, air and surface temperature, finally reducing the occurrence of disease in winter wheat.3. Effects of planting patterns on leaf physiological characteristicsThis study indicated that populations with relatively uniform distribution would improve leaf relative water content (RWC), water potential (Ψw), and osmotic potential (Ψs) and so on in summer soybean. The furrow planting improved leaf water characters, enhanced photosynthetic rate (Pn) and fluorescence in flag leaves of winter wheat, consequently maintain well leaf water characters and physiological functions. Irrigations had a significant effect on leaf physiological characteristics. RWC,Ψw, Pn and fluorescence rose with the increase of irrigation amount.4. Effects of crop planting patterns and irrigation on the law of water consumptionThe soil moisture content had no significant differences among different planting patterns in summer soybean. The field evapotranspiration of A treatment was significantly lower than that of the other treatments, and there were no significant differences among others. Compared with other treatments, A and B treatment could increase the soil moisture content in 0³0cm soil layer and soil storage water, and the soil moisture content in 0³0cm of A treatment was 6.23% higher than that of E treatment.The furrow planting of winter wheat significantly improved the soil moisture content and soil storage water, and reduced the field evapotranspiration. The study also indicated that irrigation could increase the soil moisture content and total evapotranspiration, and reduce the difference among planting patterns in winter wheat.5. Relationships of planting patterns, yield, WUE and RUEThe study found that the yield of A, B treatment in summer soybean and furrow planting in winter wheat had highest yield and WUE. The direct reason of yield increased was that the productive pod, seed numbers and 100 seed weight significantly increased in summer soybean or kernel numbers and thousand kernel weight significantly increased in winter wheat. The direct reason of WUE increased was that the field evapotranspiration reduced and yield significantly increased. Moerover, furrow planting can significantly improved RUE. The yield and RUE of winter wheat gradually raised, however, WUE significantly declined with the increase of irrigation amount. Planting pattern and irrigation both significantly affected WUE; moreover, they had a interaction with each other.The yield were positively correlated with WUE in summer soybean (R=0.998**); and the yield were positively correlated with WUE and RUE in winter wheat(R=0.998*, 0.992*). The yield of furrow planting in 135mm irrigation amount had no difference with uniform (25 cm) row in 180mm irrigation amount. In other words, compared with uniform (25 cm) row the furrow planting saved water by 25%. In conclusion, on this testing condition, the B treatment (27cmx12cm) of summer soybean and the furrow planting under the irrigation amount of 135mm of winter wheat were the optimal planting patterns.