Effect Of Phosphorus On Yield,Quality,Nutrient Absorption And Seedling Cold Tolerance Of Watermelon

The experiment study obstacles of chilling injury on watermelon seedling stage, impact of lack and excessive of nutrients on watermelon growth process,and the most appropriate local watermelon nutrient usage and management,as well as the growth and development of physiological,the main results were shown as followed:1 Nutrient solution experiments results were shown:phosphorus and boron promote watermelon seedling growth,improve seedling resistance to the cold,so appropriate dosage of phosphorus and boron is an important measure on watermelon seedlings:1.1 phosphorus deficiency lead to reduce watermelon leaf area,and slow growth rate of leaves,and its less affected by boron deficiency,but adding suitable boron with phosphorus can promote watermelon seedling normal growth and development, reduce cold injury index,raising the watermelon seedling cold tolerance.1.2 Phosphorus,boron and its cooperation can promote transportation and absorbtation of nitrogen,phosphorus and potassium from roots to ground,especially phosphorus with boron is more prominent,which can promote the roots' absorption of nitrogen,and nitrogen's transportation and accumulation to ground,thereby promoting the growth of plants.Boron deficiency more inhibited the crops to absorption of phosphorus,caused the decline in phosphorus content,and boron can promote the absorption of phosphorus under appropriate amount of phosphorus;also boron deficiency,phosphorus inhibit crops to uptake boron,and more sharpened the lack of boron,at room temperature,boron inhibits the absorption of magnesium in watermelon seedlings,and low temperature increase the absorption of magnesium. boron deficiency under low temperature conditions,normal phosphate level has a trend to suppress calcium absorption.1.3 Low temperature,phosphorus with boron can improve soluble sugar content and reduce the content of MDA and conductivity,this means that under low temperature stress,phosphorus combined application of boron can reduce electrolyte leakage of water potential and maintain the stability and greatly ease watermelon seedling membrane for the injuries suffered.Soluble sugar and conductivity can be used as a more rapid identification of watermelon seedling cold tolerance indicators.2 The sand experiments results were shown:the amount of phosphorus has different impacts on watermel growth and nutrient absorption,and ultimately affect the yield and quality:2.1 Excessive phosphorus inhibits leaves' absorption and utilization to iron,so decreasing chlorophyll content;the use of excessive phosphorus lead to light green leaf color,the actual observation of this is the case.therefore,"dilution effect" can not fully explain the high phosphorus led to the phenomenon of lower chlorophyll content.2.2 If the supply of phosphorus is not sufficient on watermelon flowering period, which will reduce nucleic acid synthesis,thus affecting or inhibiting the growth of crops and delaying childbearing period,also excessive amount of phosphorus will low down the stem cellulose content.2.3 Growth of watermelon early,nitrogen,phosphorus,and potassium content increases with phosphorus level,and bloom,fruit and maturity period,leaf nitrogen content shows a downward trend,phosphorus inhibits part of the ground absorption of Ca,Mg,Cu,Zn and Fe,but promotes absorption of B,Mo and Mn.but the promotion or inhibition of nutrients may be effected by crop varieties,crop growth stages and different parts of the crops.2.4 phosphorus deficiency led to a decline in yield of watermelon,and increasing of watermelon seed;excessive phosphorus also results yield decline from inhibiting crop on nitrogen uptake and functioning,and at the same time it leads to some increases in the percentage of gluten.2.5 Malic acid and citric acid are not the main factors in affecting effective acid of watermelon,malic acid and lycopene have the highest content under appropriate amount of phosphorus,it shows nutrient balance is important to synthetic or decomposition of the two components,and not the absolute amount of phosphorus. Phosphorus has greater impact on the sugar,and little effect on the acidity. phosphorus deficiency leads to soluble sugar uneven distribution in the watermelon flesh,which through soluble sugar move to central,so the overall impact on watermelon flavor.The sucrose,fructose,glucose sugar are common affecting factors in sweetness of watermelon,as which soluble sugar is major affecting factors,that may be associate with crop species,growth stage,as well as the comprehensive factors such as fertilizer.3 The field experiment results were shown:phosphorus can increase the number and weight of watermelons,and raise yield of watermelon;effect of phosphorus is better on increasing number of watermelons,for the yield,with the increased amount of phosphorus,watermelon production added,but to a certain volume,a low trend started,content of soluble sugar have same trend with yield basically,in certain areas, vitamin C content can be increased with phosphate added,phosphate also have a great impact on content of nitrat,the trend is,the nitrate content of the treatments that used phosphate is significantly over CK.In the words,P₃(150 kg/hm²) is more appropriate to add yield and improve quality.