南疆长期漫灌红枣改滴灌根系演变规律及调控模式研究

With the structural adjustment of agriculture in South Xinjiang, the cultivated area of jujube trees extends continuously, which resulted in the sharp increase of oasis agricultural water consumption along the Tarim River. Change the irrigation pattern of jujube trees from flood irrigation to drip irrigation is imperative as the critical shortage of water resource. As the adult jujube trees were flooding irrigated for years, the plant growth especially the root development was adapted to flooding irrigation, the local farmers are afraid that, after using drip irrigation, the root system would be irreversibly harmed by the local water and fertilizer supply, which made it difficult to promote drip irrigation technique. The long-term flooding irrigated jujube trees from desert oasis area of south Xinjiang were studied, and the laboratory simulation and field experiment were adopted to study the with in the year and interannual space-time redistribution and evolution rule of the jujube trees after drip irrigation, define the response relationship between root distribution and soil moisture area, explore the effect of drip irrigation on water deprivation, physiological property, yield and quality of jujube trees, and finally establish suitable adjusting and controlling patterns. The theoretical basis and technical support would be provided to increase the use ratio of water resource in south Xinjiang and promote drip irrigation in jujube plant by this research achievement.

随着南疆农业结构调整，红枣种植面积不断扩大，以塔里木河为水源的绿洲农业用水量日益增加，水资源严重短缺，枣树漫灌改滴灌势在必行。由于成龄枣树经过多年连续漫灌，植株生长尤其根系发育方面已经适应漫灌方式，当地农户担心由漫灌改滴灌后，局部水肥供应将对枣树根系造成不可逆的伤害，使得滴灌技术推广困难。本课题以南疆荒漠绿洲区长期漫灌红枣为研究对象，通过室内模拟和大田试验的方法，研究红枣漫灌改滴灌根系年内、年际间时空再分布及演变规律，明确根系分布与土壤湿润区之间的响应关系，探明漫灌改滴灌对红枣耗水规律、生理特性、产量和品质的的影响，构建适宜的漫灌改滴灌调控模式。研究成果将为提高南疆地区水资源利用率及滴灌技术在红枣种植业中的推广提供理论依据和技术支撑。

南疆红枣经过多年漫灌，其生长发育特性尤其根系分布与漫灌方式相适应，直接利用滴灌代替漫灌，大幅度降低灌水量，势必对一部分根系造成水分亏缺，对枣树生长不利。本项目针对长期漫灌红枣开展滴灌调控试验，研究了长期漫灌改滴灌对红枣生理生长特性，根系演变，产量及品质的影响，并提出了南疆长期漫灌红枣改滴灌适宜的水肥耦合模式和灌水模式。根据研究目标，项目组开展了连续4年的滴灌调控试验，主要研究结论如下：. （1）高水处理对表层土壤保水性和盐分的淋洗具有良好效果；增加施肥会导致表层盐分升高；从脱盐量的角度分析，滴灌条件下各处理均处于脱盐状态。中水高肥处理土壤养分最高，有利于作物保持一个较好的土壤养分环境。 . （2）综合水肥耦合对滴灌红枣生理生长、产量及品质的影响，最优水肥组合为灌水820 mm、施肥量765 kg/hm2。通过建立水肥投入与产量、品质回归方程，模拟计算出适宜灌水施肥量分别为651～806 mm 和708～810 kg/hm2，其中N（311～345 kg/hm2）-P2O5（156～178 kg/hm2）- K2O（233～267 kg/hm2）。. （3）滴灌有效控制了土壤湿润区范围和土壤含水率，660～880 mm灌水量可显著提高枣树关键生育期根区土壤储水量。随着滴灌带铺设间距的增大，土壤湿润区范围由窄深变为宽浅。提高灌水量，可显著提高土壤湿润区范围和土壤含水率。. （4）漫灌改滴灌后，枣树根系受滴灌调控效果显著，逐渐向湿润区内聚集，660～880 mm的灌水量可显著提高了0～60 cm土层根长密度。440 mm的灌水量形成的土壤湿润区范围和土壤含水率对枣树产生了明显的水分胁迫现象，湿润区内根长密度未明显增大。35～50 cm滴灌带铺设模式下所形成的宽浅型土壤湿润区与枣树根系分布更加匹配。. （5）漫灌改滴灌显著降低了红枣耗水量，提高了水分利用效率。滴灌红枣生育期内耗水量随着灌水量的增加逐渐增大。改滴灌初期，35～50 cm的滴灌带铺设模式和660 mm的灌水量更有利于提高红枣产量和水分利用效率。