蓄水坑灌条件下苹果园水分运移机制与调控研究

In recent years, the planting area and output of apple in China rank first in the world. However, apple production regions in China are mainly situated in semi-arid areas where the problems include local water scarcity, drought and low water use rate are serious and directly restrict apple quality and the sustainable development of apple production. Therefore, it is considerably urgent to find out the water transport mechanisms and water regulation measures in orchards. The change of irrigation method will alter the water migration way and the water storage pit irrigation is a significant water saving and water retention irrigation method which irrigate water directly in the middle-deep soil layers. The project is conducted by using the research method that combines the theoretical analysis, indoor and outdoor experiments together. Under the water storage pit irrigation condition, firstly the project analyses the temporal and spatial distribution of absorption root of apple trees; uses the hydrogen and oxygen isotope technology to research the main water absorption part apple tree root and establish water absorption models. Secondly, finds out the water transport mechanisms in the SPAC system and explore the physiological indicators threshold of apple trees. Thirdly, uses carbon isotope technology to research water use efficiency of apple trees in different time scales. Based on the researches above, the orchard irrigation strategy will be optimized and be tested through experiments. Finally high-efficiency water regulation measures under the water storage pit irrigation will be proposed. There search findings are theoretically significant and can be utilized as guidance for appropriate orchard irrigation management and eventually contribute to high water use rate, water saving, high yield and fruit quality .

近年来，我国苹果种植面积和年产量均居世界首位。但苹果产区主要处于半干旱地区，存在着当地水资源紧缺、干旱，而水分利用率低的问题，直接影响苹果的产量，制约着苹果产业的可持续发展。因此，研究苹果园水分运移机制并进行调控尤为迫切。蓄水坑灌法是一种节水保水性明显的中深层灌溉方法，灌溉方式的改变直接影响苹果园水分的运移。项目采用理论分析、室内外试验相结合的方法，分析苹果吸水根时空分布及其对土壤水分的响应，利用氢氧同位素法，研究蓄水坑灌条件下苹果各生育阶段根系的主要吸水区域，建立根系吸水模型；研究基于果树生理指标的果园SPAC系统水分运移规律，寻求苹果生理指标阈值；利用碳同位素法，分析蓄水坑灌条件下苹果树不同时间尺度的水分利用效率。在此基础上，优化苹果园灌水策略与试验，提出蓄水坑灌条件下苹果园水分高效利用调控措施。成果对于我国苹果园合理灌溉，提高水分利用率，实现果园节水增产具有重要的理论意义和实用价值。

如何高效利用日益短缺的水资源以达到节本提质增效的目的，是现代果园可持续发展亟待解决的问题，也是黄土高原建设生态果园的必由之路。蓄水坑灌法在我国北方果林中具有广阔应用前景。蓄水坑灌法是一种节水保水性明显的中深层灌溉方法，灌溉方式的改变直接影响苹果园水分的运移。深入研究蓄水坑灌下苹果园水分运移机制，进一步揭示蓄水坑灌的节水机理，对指导蓄水坑灌下果园的合理灌溉具有重要意义。项目采用理论分析、室内外试验相结合的方法，利用氢氧稳定同位素技术并结合根系分布以及根系活力情况，量化了蓄水坑灌下苹果根系的主要吸水深度为20-100cm，根区40-100cm土层的土壤水贡献率显著提高，建立了蓄水坑灌下根系吸水模型，模型平均相对误差5.42%。阐释了蓄水坑灌下果树地上部SPAC系统水势-直径微变化-叶片气孔对土壤水分变化的响应机制，表明了蓄水坑灌下叶水势阈值低于-0.48MPa，其树干直径日最大收缩量（MDS）与40-80cm深度土壤含水率、液流速率均呈正相关，气孔导度与细根长呈正相关，并建立了蓄水坑灌下的气孔导度模型，模型平均相对误差1.89-8.93%。定量了不同时间尺度的水分利用效率，与地面灌溉相比，蓄水坑灌不同处理下苹果树的瞬时叶片水分利用效率提高了13-19%，产量水平的水分利用效率提高了26.5-28.6%，叶片碳稳定同位素指示的长效水分利用效率显著增加。提出了蓄水坑灌条件下苹果园节水增产增效的水分调控措施，定量了蓄水坑灌下苹果树全生育期蒸散量，并基于SW双源模型建立了蓄水坑灌苹果树蒸散模型，均方根误差为0.63mm/d，基于模糊综合评判模型得出蓄水坑灌下最优灌水方案为，在萌芽花期的灌水上下限分别为60%-80%，在新稍旺长期的灌水上下限为70-90%，在果实膨大期的上下限为80-100%。成果对于我国苹果园合理灌溉，提高水分利用率，实现果园节水增产具有重要的理论意义和实用价值。