节水灌溉技术下星油藤高产高效栽培的水肥耦合效应及其机理

It has great significance to meet the needs of China's edible vegetable oil to find new woody oilseed plants with excellent features. Plukenetia volubilis, a promising woody oilseed crop indigenous to South America, was successfully introduced, and are developing in SW Yunnan China and north Loas, where 95% of the land is covered by mountains. Dry and infertile soil are the key limiting factor for the crops' growing in these regions. Besides, because of the shortage of water resources, especially in recent consecutive years due to severe drought, the development of water-saving technology (e.g, Regulated Deficit Irrigation, Partial Root-zone Drying) is the inevitable trend of agricultural modernization. To date there is a lack of detailed information about cultivation potential. In this proposal, we will present a comparative analysis on the seasonal and yearly variations of plant growth, morphology, carbon and water physiology, and reproductive traits (flower numbers, fruit set, seed yield and quality) of P. volubilis plants cultivated under the combined effects of fertilization and water-saving irrigation in Xishuangbanna Tropical Botanical Garden (alt.560 m). We will analyze the plant growth difference from the carbon balance, and unravel the mechanisms of the seed yield and quality from the relationships between growth, reproductive traits and environmental factors. In addition, we try to know seasonal variations of the water sources and their reltive contribution to the water uptake of P. volubilis plants during different growth stages, by hydrogen and oxygen stable isotope thechnology. Overall, we will clarify the eco-physiological mechanisms of the dynamic balance between plant growth, allocation and seed metabolites (mainly protein and lipid), the physiological mechanism of water-saving irrigation technologies, as well as understand the approaches to increase the seed and oil yield and resouce use efficiency under the combined effects of fertilization and water-saving irrigation conditions. If this project can be supported, the research findings will reveal the temporal dynamics of seed yield and quality formation, and its yield formation of the constraints and the regional potential, to provide a theoretical basis and technical support for mountain planting promotion and industrial development of P. volubilis plants.

通过节水灌溉技术（调亏灌溉和根系部分干燥）下，水分和施肥量两因子的长期田间试验，本项目研究新型木本油料植物星油藤植株的干物质积累、碳摄取(光合碳同化)、损失(呼吸)、投资(非结构性碳水化合物含量及其分配)、水分生理和繁殖特征（开花、坐果率，种子产量和品质等）季节和年份的动态变化。从星油藤的光能利用和碳平衡阐述植株生长的生理生态学机理；从星油藤的生长、繁殖特征与环境因子的关系分析其物质生产、分配和种子代谢物动态协调及其调控原理。明确节水灌溉技术对星油藤水分利用效率和产量形成的作用，以及生理节水机理；探讨星油藤高产与资源（水分、养分）高效利用的途径。同时，运用氢氧稳定性同位素技术探讨星油藤不同发育时期、不同季节的水分利用策略以及节水灌溉对其的影响。研究结果将阐明水肥耦合与产量形成的关系，提出星油藤高产与资源高效利用种植的生产模式及其栽培调控途径，为其山地种植推广和产业化提供依据。

节水灌溉技术是提高作物产量和资源利用效率的重要管理措施，本项目研究结果表明：（1）田间星油藤植物生长对季节性干旱的敏感性相对较低，这可能由于其极低的根生物量比和田间干旱仅仅对叶片光合特性的短期季节性影响以及水分主要老源于土壤浅层有关。干旱条件下，幼苗生长比大田大植株对干旱有更高的敏感性。在相同灌溉量下，虽然交替节水灌溉比亏缺灌溉技术对于幼苗和大田作物都更节水，充分灌溉对幼苗的生长最佳，但以水分利用效率为代价。在灌溉和施肥处理中，种子平均粒径和平均种子油浓度均是由单位面积的种子数决定的。可溶性糖和氮是有效花形成相关，果实和增加星油藤产量的起着十分重要的作用；种子总产量与植物组织的总氮库和非结构性碳水化合物库有密切正相关。施肥增加种子总产量和总产量的种子油，但没有灌溉×施肥交互作用。虽然具有较高的水分利用效率，与充分灌溉相比，中度和重度亏缺灌溉造成星油藤的产量损失。作为一个需水类的作物，星油藤在100蒸腾量和充分灌溉条件有最高的总产量和营养利用效率，但在水分利用效率为代价。最大产量和最大水分利用效率，或最大营养利用效率和最大水分利用效率存在权衡关系。相比于充分灌溉，亏缺灌溉可以节约用水，但减少了总的种子产量和较低的养分利用效率。而交替节水灌溉与充分灌溉有类似的总产量和养分利用效率，但大大减少水的使用。交替节水灌溉成功地减少了水和肥料的使用。（2）通过田间干季试验确定叶面喷洒不同激素对星油藤生理生态和产量性状的影响。植物生长调节剂对总产量（增加4.3%到15.2%）和总种子含油率（增加4.9%到24.9%）的正面影响。与对照相比，在整个生长季节单位面积的产量在很大程度上取决于营养生长和生殖生长之间的平衡。植物生长调节剂，尤其是ABA和SA，可以成为提高星油藤种子油产量和质量的有效途径之一。（3）从不同的土地使用历史（休闲地、茶地、水稻地、香蕉地、玉米地）分析的表明，玉米田农场土地利用转换成星油藤种植地能有效维持土壤微生物数量，可作为土壤可持续发展的有效途径。在各种土地利用类型中（在很小的地理范围），土壤微生物类群组成明显不同，尤其是真菌。但在农业干旱地（橡胶和星油藤种植地）和森林演替后期阶段之间，土壤微生物多样性没有很大的差异。热带森林演替和森林转化为农业旱地影响微生物物种的分布，而微生物多样性并不遵循演替规律。