番茄优质高效的水钾耦合响应机制与灌水施钾模式研究

In many parts of the world, the scarcity of high quality water and fertilizer is in contradiction to resource waste and chemical fertilizer pollution to environment from excess irrigation and/or irrational fertilization. Moreover, the vegetable yield is increasing but the quality tends to decline due to excess irrigation and irrational fertilization. This is in contradiction with increasing public awareness of health and nutritional food. One of scientific research focus in Irrigation Science and Soil Science,Horticulture as well as Plant Ecophysiology is to obtain vegetables of very high health quality and high crop use efficiency of water and fertilizers through optimizing irrigation and fertilization practice on the basis of potential plant acclimation to its environment. The tomato is the second popular vegetable and tomato fruits are an excellent source of vitamins C and lycopene, which collectively may lower the risk and occurrence of some cancers and heart disease. The potassium (K) requirement of tomatoes is high for vegetative growth, fruit production and fruit quality. Moreover, plant resistance to stresses is closely related to plant K status. The content of lycopene and vitamin C, soluble sugar as well as titratable acid in a tomato fruit is regarded as the most commercially and nutritionally important quality traits. Therefore, in this research proposal, tomato plants will be grown in soilless culture and field or greenhouse subjected to different amounts and time of irrigation as well as different rates and time of K fertilization. The magnitude of response which the treatments impose on the nutritional traits of tomato and the status of plant water and K nutrition will be investigated to define the sensitive tomato nutritional traits to irrigation and K nutrient and their sensitive supply time. Furthermore, the effect of the treatments on leaf photosynthesis, transport and partitioning of assimilates and the activity of key enzymes as related to synthesis and metabolism of lycopene and vitamin C, sugars as well as organic acid in tomato fruit will be identified to provide numerous insights into the source-sink relationship and metabolic pathways of tomato fruit quality response to water and K nutrient supply during fruit development. Also, the project will seek the resource management techniques to adopt for improvement of the health-promoting phytochemicals of tomato and enhancement of crop water use efficiency and fertilizer use efficiency based on maximization of physiological regulation of plants itself to environmental factors.

面对水肥资源紧缺与浪费的矛盾、蔬菜产量增加而品质下降与人们追求食物安全与营养的矛盾，如何充分挖掘植物自身对水分、养分的适应潜力，以期达到蔬菜优质高效灌溉施肥，是近年来广为关注的热点问题。番茄是第二大蔬菜作物，吸钾量居各元素之首；钾又是公认的"品质元素"，且与植物抗逆性密切相关。因此，项目通过基质栽培和田间试验，研究番茄果实中番茄红素、Vc、可溶性糖、可滴定酸含量等品质指标对水分与钾素状况的响应关系，筛选番茄水、钾敏感的单项品质指标及其敏感时期；揭示果实发育过程中同化物形成、运输与分配以及营养物质累积关键相关酶活性的变化特征，探明果实品质形成与源库关系和关键酶活性间的内在联系，揭示番茄品质对水、钾响应的生理机制；同时，综合考虑番茄产量、综合营养品质及水分、养分利用效率，探索最大发挥植物自身生理调节功能、提高番茄品质和资源利用效率的水分与钾素调控措施，为蔬菜优质高效施肥灌溉寻求更为有效的途径。

面对水肥资源紧缺与浪费的矛盾、蔬菜产量增加而品质下降与人们追求食物安全与营养的矛盾，如何达到蔬菜优质高效灌溉与施肥，是近年来广为关注的热点问题。项目对番茄苗期、始花结果期、果实生长初期、膨大期及品质形成期设置不同的水、钾供应，通过盆栽试验及大棚试验，针对产量及果实可溶性糖、番茄红素、Vc含量以及植株水分与钾素状况、营养物质代谢相关酶活性等对水钾供应的响应进行了系统研究，获得如下重要结果：（1）探明了番茄品质指标受果实发育阶段土壤水分的影响显著大于苗期及始花结果期，但各项品质指标对土壤水分敏感的时期不同，如Vc对品质形成期最敏感，而可滴定酸含量对膨大期的敏感性大于其他阶段。（2）揭示了番茄红素和Vc含量对除苗期外其他阶段施钾均有明显响应，而可溶性固形物、可溶性糖及糖酸比对品质形成期施钾更敏感；而且，各项品质指标对品质形成期施钾的响应与膨大期钾肥施用有关。（3）探明了番茄可溶性糖、可滴定酸等风味品质对膨大期、品质形成期施钾量的响应明显大于土壤水分；番茄红素、Vc含量对膨大期土壤水分、施钾量及其互作的响应均极显著，而仅对品质形成期土壤水分敏感，但具体响应与施钾量有关。（4）揭示了膨大期土壤水分为70%~80%θf、施钾量为0.46 g K2O /kg土正是由于增强中性和酸性转化酶活性、抑制蔗糖合成酶和蔗糖磷酸合成酶活性而促使可溶性糖累积，膨大期高水平施钾在花后40d使果实累积钾素大幅增加而不利于糖分累积。（5）探明了番茄花后35d至果实成熟、特别是47d以后，半乳糖内酯脱氢酶活性快速增大，而脱氢抗坏血酸还原酶活性在花后35d至果实成熟呈持续增大趋势；揭示了番茄Vc含量与这两种酶活性间有极显著的相关性。（6）以产量、综合品质以及水肥利用效率为评价指标的番茄水肥管理综合评价表明，番茄稳产优质高效的灌水量、施氮量、施磷量、施钾量、有机肥用量分别为482~494mm、744~797 kg N/ha、339~376 kg P2O5/ha、687~729 kg K2O/ha、429~466 m³/ha。以上结论为蔬菜优质高效施肥灌溉提供了理论与技术支撑。