西北干旱地区农业健康用水量计算模型研究

为明确灌溉模式对不同群体小麦光合特性的调控机制,在大田条件下设置了不灌水(W0)、灌1水(W1j,拔节期灌水;W1b,孕穗期灌水)、灌2水(W2,拔节期和孕穗期灌水)、灌3水(W3,拔节期、孕穗期和灌浆期灌水)5种灌溉模式和基本苗180株.m?2(D1)、300株.m?2(D2)和450株.m?2(D3)3种密度的二因素试验,研究了灌溉模式对不同群体小麦光合特性的影响。结果表明:灌溉明显改善了群体光合速率。在一定灌溉总量范围内,灌溉次数与群体光合速率呈抛物线型关系。较多的灌溉次数下群体光合速率的提高归因于LAI增大和群体光截获的增加。群体光合速率与冠层透光率呈极显著的负相关,灌浆期群体光合速率与花后干物质积累量和产量呈极显著的正相关。主效应及偏相关分析表明:W0、W1j、W1b、W3群体光合速率主要受群体透光率和叶面积的影响,W2群体光合速率的提高主要受旗叶净光合速率的影响。综合产量和群体光合速率等因素,春季灌2水(拔节水和孕穗水)的小麦群体上层截获光较多,中下层通风透光良好,群体光合同化能力最强,花后干物质积累量和产量最高;在此基础上采取密度为300株.m?2基本苗能够提高生育后期的群体光合速率,延长其高值持续时间,增加小麦籽粒产量。

Health volume of agricultural water consumption and its calculation model in the Heihe River Basin

With competition between agriculture and other industries in the northwest arid areas of China, determination of healthy volume of agricultural water consumption provides the basis for reasonable distribution of available water resources. Based on healthy agricultural water volume connotation and standard, a multi-objective optimization layer calculation model was developed for the northwest arid areas of China. The model achieved its objective function not only for maximum water consumptions in different industries, but also for total water consumption. It also successfully calculated the healthy volumes of agricultural water consumption in different areas under given optimization sequences. The model was successfully tested in calculating healthy volume of agricultural water consumption in the Heihe River Basin (HRB). For different county-level administrative units, the healthy volume of agricultural water consumption was evaluated under different water inflow frequencies for the past (1999), present (2006) and future (2020) years. The results show that model-adjusted water resources allocation in 1999, 2006 and 2020 reduced the basin water volume consumption (in the agricultural and industrial sectors) by 2.7%, 4.6% and 2.1%, respectively. Water benefit was comprehensively increased by 7.1%, 16.6% and 13.1% in 1999, 2006 and 2020, respectively. Similarly, ecological benefit respectively increased by 27.6%, 37.4% and 13.6% in the above periods. Not only was the model reliable, but the feasibility of healthy agricultural water consumption in the region increased. Comparisons of healthy agricultural water consumption among different years revealed that the water situation in the agricultural sector in 2006 was healthier than in 1999. Also the situation in 2020 was healthier than in 2006. While agricultural water use ratios reduced by 3.4% and 2.0%, water efficiency increased by 31.1% and 91.6%, respectively. Based on previous agricultural water distributions, the basin water deficit in 2020 was predicted at 10.6%, 13.8% and 25.9% under 50%, 75% and 95% of water inflow frequencies. It showed higher scarcity of water resources then. It was concluded that in order to meaningfully curb water shortage, water resources allocation should be adjusted based on healthy volumes of agricultural water consumption.