Study On Soil Water Low Limit Of Drip-Irrigated Muskmelon (Cucumis Melo L.) In Plastic Greenhouse

Muskmelon (Cucumis melo L.) is an important horticultural crop in the world, and is quite sensitive to water stress. Water deficit can cause fruit yield reduced, on the other hand, excessive water can cause fruit quality severely reduced. Soil water is one of the most important factors affecting the yield and quality of muskmelons. The precipitation is abundant in the area of Southern China. Muskmelon is usually planted inside plastic greenhouse or solar greenhouse. High yield of top quality is an object for profitable production of muskmelon in China. In recent years, muskmelon production has been plagued by inferior quality problem because of improper water management. So studying on regularity of water requirement and irrigation schedule of muskmelon growing in field has important sense to understand the upgrading yield and high quality of muskmelon and raising the utilization ratio of water. The object of this study was to determine the soil water content at which growth and yield production of muskmelon would be optimal based on Time Domain Reflectometry (TDR) inside the plastic greenhouse when using drip irrigation.1. Plant height, stem diameter and leaf area decreased as well as soil water low limit declined. Before the tips were pinched, the plant height growth rate increased faster initial, and grow slower after. Plant height and stem diameter growth showed obviously compensation effect with irrigation water amount increased on reproductive stage. If the threshold of soil water low limit was too small, it would be adverse for muskmelon vegetative growth.2. Leaf water content and leaf chlorophyll content decreased as well as soil water low limit declined. We can master the change regularity of chlorophyll content from the dynamic change of SPAD value during muskmelon growth period.3. Malondialdehyde content and Proline content increased as well as soil water low limit declined. Water stress promote accumulate of MDA and Pro.4. When soil water low limit was below 65% field capacity on vegetative growth stage, the mean fruit weight and yield decreased significantly. When soil water low limit was below 75% field capacity on reproductive stage, the mean fruit weight and yield decreased significantly.5. Different soil water low limits were set up during the whole growth period, T65 (65% field capacity) was the best treatment in quality. Different soil water low limits were set up during the vegetative growth stage,Ⅰ55 (55% field capacity) was the best treatment in quality on spring, R65 (65% field capacity) was the best treatment in quality on autumn.6. Different soil water low limits were set up during the whole growth period, irrigation water use efficiency was decreased as well as soil water low limit declined, T75 (75% field capacity) was the highest treatment by the value 153.7 kg/(ha mm). Different soil water low limits were set up during the vegetative growth stage,Ⅰ65 (65% field capacity) was the best treatment in irrigation water use efficiency on spring, R65 (65% field capacity) was the best treatment in irrigation water use efficiency on autumn.7. Therefore, base on production and quality,65% field capacity would be the most appropriate thresholds for muskmelon starting irrigation on vegetative growth stage, and 75% field capacity would be the most appropriate thresholds for muskmelon starting irrigation on reproductive stage.