Effects Of Water Regulation And Topdressing Phosphate Fertilizer On Growth,Yield And Nutrient Absorption Of Muskmelon In Greenhouse

The effect of water and phosphorus on the yield and quality of muskmelon in greenhouses in the arid and cold region of Haiyuan in Ningxia was not obvious.Through a two-factor randomized block test,Two water control levels,W1（-20kPa）and W2（-40kPa）,and five topdressing levels of P2O5,P0（0kg/hm²）,P1（21.15kg/hm²）,P2（58.65kg/hm²）,P3（96.15kg/hm²）and P4（133.65kg/hm²）,were set.The effects of topdressing amount of P on water consumption,growth,yield,quality,plant nutrient absorption and accumulation of available P in soil of muskmelon in greenhouse were studied under different water conditions.The main conclusions are as follows:（1）During topdressing period,the water consumption of muskmelon was the largest during the expansion period,followed by the flowering period and the sitting period.The pattern of water consumption shows a "single peak" curve.Under the same phosphate fertilizer level,the water consumption and water consumption intensity increased with the increase of water level.Under the same water condition,the water consumption firstly increased and then decreased with the increase of phosphate fertilizer level.During top dressing,the cumulative water consumption of W1P3 treatment was the highest,which was 186.46mm,and the water consumption intensity was 3.26mm/d.（2）Under the same water condition,the growth indexes increased first and then decreased with the increase of phosphorus fertilizer level.Compared with W1P0,stem diameter,leaf number,SPAD value and dry matter weight of W1P2 increased by 4.24%,8.82%,8.16%and 31.48%,respectively.When P₂O₅ topdressing level was 0～58.65kg/hm²,stem diameter increased with the increase of water regulation level,and when P₂O₅ topdressing level was 96.15～133.65kg/hm²,stem diameter decreased with the increase of water regulation level.A quadratic parabolic function with downward opening can be established between the length of main stem and the amount of topdressing phosphorus fertilizer.At the level of W1,when the amount of topdressing phosphorus fertilizer was 68.48kg/hm²,the length of main stem reached the maximum.When the topdressing amount of P fertilizer was 71.43kg/hm² at W2 level,the main vine length reached the maximum.The results showed that under the condition of better W1 moisture,the amount of topdressing phosphorus fertilizer was less and the effectiveness of phosphorus fertilizer was higher.Under the same water condition,the net photosynthetic rate and stomatal conductance first increase and then decrease with the level of phosphate fertilizer.The intercellular CO₂ first decreases and then increases with the level of phosphate fertilizer;under the same phosphate fertilizer condition,the transpiration rate increases with the increase of water level.（3）Under W1 water condition,the topdressing level of P₂O₅ was 58.65～96.15kg/hm²,which could significantly increase the yield,vitamin C and protein content of melon fruit.Under W2 water condition,topdressing P₂O₅ at 0～58.65kg/hm² could improve the soluble sugar content and fruit quality of muskmelon.The interaction of water and phosphorus had significant effect on yield and fruit protein content.Under W1 and W2 water conditions,the quadratic parabola function with downward opening between yield and topdressing amount of P can be established,and the maximum yield can be achieved when P topdressing amount is 66.41kg/hm² at W1 level.At W2 level,the maximum yield was achieved when the topdressing phosphorus fertilizer was 70.75kg/hm².Under W1 and W2 water conditions,a downward quadratic parabola function between soluble sugar and topdressing amount of P could be established.At W1 level,when the topdressing amount of P was 45.0kg/hm²,the soluble sugar content was the highest.At the W2 level,the soluble sugar content was the highest when the topdressing phosphorus fertilizer was 47.2kg/hm².By comprehensive comparison,when W1 water control level and P2O5 topdressing amount was 58.65kg/hm²,muskmelon growth was better,yield and quality were higher,which was a more suitable integrated management mode of water and phosphorus under drip irrigation in local melon.（4）The accumulation of nitrogen,phosphorus,and potassium nutrients of muskmelon under different water and phosphorus treatments showed an upward trend with the advancement of growth period.Compared with other treatments,W1P2 treatment increased the nutrient absorption of nitrogen,phosphorus and potassium of muskmelon to different degrees.During the whole growth period,the nutrient absorption of greenhouse muskmelon was potassium>nitrogen>phosphorus.The absorption ratio of nitrogen,phosphorus and potassium is 1:0.35:1.72.The nitrogen uptake of melon in the mature period is 3.17～4.55g/plant,the phosphorus uptake is 1.04～1.60g/plant,and the potassium uptake is 5.72～7.81g/plant.（5）The accumulation of nitrogen,phosphorus,and potassium nutrients of muskmelon under different water and phosphorus treatments showed an upward trend with the advancement of growth period.Compared with other treatments,W1P2 treatment increased the nutrient absorption of nitrogen,phosphorus and potassium of muskmelon to different degrees.During the whole growth period,the nutrient absorption of greenhouse muskmelon was potassium>nitrogen>phosphorus.The absorption ratio of nitrogen,phosphorus and potassium is 1:0.35:1.72.The nitrogen uptake of melon in the mature period is 3.17～4.55g/plant,the phosphorus uptake is 1.04～1.60g/plant,and the potassium uptake is 5.72～7.81g/plant.