| The shortage of water resources has become a global issue. Drought and water shortage is an important constraint restricting sustainable social development, constitutes a serious threat to food security production. In view of the increasingly scarce water resources and the intensification of the drought trend in sustainable agricultural production should not simply the pursuit of high-yield goal should be to the great importance to crop water use efficiency (Water Use Efficiency, WUE) of the improvement as a key to efficient water. Biological water saving raise output and WUE with biological function which has a little input and high benefit and big potential. It suits the national conditions of our country. Sorghum is widely grown in arid, semi arid region of china. Water is the primary limiting factor of regional agriculture. It is greatly meaningful to plant sorghum with the biological measure of water saving. There are mainly two biological ways available to save water:1as the point of hereditary view, establishing appraisal system and screening suitable breed to raise WUE;2from the environmental angle, studying water demand regulation of sorghum and find out the efficient irrigation quota, to realize the balance of WUE, output and water consumpation.In this research, the irrigation amounts were determined by the evaporation from a standard20cm diameter pan placed above sorghum canopy, with the use of drip irrigation to control the volume of irrigation, studies the possibility to realize efficient water use of sorghum production under field conditions. The field experiment in accordance with different irrigation volume was divided into four treatments with each repeated three times. This research is designed to study the laws of sorghum water requirement and consumption, the impact of irrigation volume on sorghum growth, physiological traits, yield, quality and grouting, and make clear the relationship between sorghum yield, water use efficiency and water consumption under different volumes of irrigation. The results showed the followings.Overall, the2011sorghum experiment from the yield showed the trend that the yield increased with the increase in the volume of irrigation. However, the measured yield under non-irrigation treatment was higher than that under low-volume irrigation treatment, though the difference was not obvious. In this experiment the yield under high-volume irrigation was up to11278.94kg/hm2, but the water use efficiency was the lowest of the four treatments. Yield under low-volume irrigation was9417.94kg/hm, lower than the9646.59kg/hm2under non-irrigation treatment, which may be due to the compensation effect of the unirrigated sorghum after the previous stress period under the conditions of more abundant precipitation in the late growth stage. Taking into account the shortage of water resources in China’s arid and semi-arid regions, it is of more practical significance to ensure higher yield under high water use efficiency. The factor that caused this result may be the compensation effect of sorghum under non-irrigation treatment after previous drought stress subject to abundant precipitation in the late sorghum experiment. To verify this possibility a water experiment was designed under the condition of rain-protection shed. Yield under high-volume irrigation was significantly higher than that of the other irrigation treatments.From the perspective of sorghum growth, the various indicators showed that within the designed scope of the experiment the larger the volume of irrigation, the more vigorous sorghum grew; the plant height, stem diameter, leaf area, etc. were the largest under high-volume irrigation. The indicator of sorghum quantity under high-volume irrigation was larger than that under low or medium-volume irrigations, for which the reason may be the same with that of the indicator yield.For sorghum cultivation in semi-arid area with relatively high precipitation, in terms of the total water resources the precipitation can basically meet the most need of sorghum growth. But the precipitation in such area shows larger inter-annual difference and the seasonal precipitation distribution is very uneven. In a particular year or a growing stage, the imbalance between water requirement and water consumption may exceed the adjusting capacity of the soil reservoir and sorghum’s tolerance, resulting in unpredictable phased drought stress, and in this case supplemental irrigation is needed. Irrigation is not simply to increase crop’s water consumption, but its main purpose is to improve the coupling between the crop’s water consumption and water requirement so as to prevent the reduction in yield caused by phased drought due to the uneven distribution of precipitation. The appropriate volume of irrigation can significantly improve the yield and water use efficiency.In this experiment, with the increase of irrigation volume, the amount of water consumed and grain yield of sorghum were increased, whereas, the water use efficiency showed a declining trend. The water use efficiency of sorghum under different treatments was calculated as21.24kg/mm.hm2under high-volume irrigation,21.83kg/mm.hm2under medium-volume irrigation,23.16kg/mm.hm2under low-volume irrigation and26.61kg/mm.hm2under non-irrigation. Among them water use efficiency under non-irrigation was the highest. For years with more abundant precipitation, sorghum under non-irrigation can achieve normal growth and obtain a higher yield. The water use efficiency of irrigated sorghum was also high, which on the one hand, is due to the use of drip irrigation in this experiment and proper field management; on the other hand, shows that sorghum’s water use efficiency is higher than ordinary crops, making it a crop that can be promoted to plant in semi-arid and arid regions. |
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