Optimization Of Nutrient Solution During Fruit Period Of Oriental Melon Grown In Bag Culture In Autumn And Winter Greenhouse

In order to optimize the nutrient solution formula of melon fruit during the development period of the nutrient substrate bag,and to clarify the nutrient absorption rule,we provide a reference for the choice of nutrient solution formula and high-yield cultivation in the integrated production of melon and water and fertilizer.This test uses the oriental melon 'Yumeiren' as the test material.During the melon fruit development period,it is divided into two tests.Test ?: Water-soluble fertilizer test with different nitrogen and potassium contents: Set P1?m_N:m_P:m _K3:1:6?,P2?m_N:m_P:m _K2:1:2?,P3?m_N:m_P:m _K2:1:1?,and CK1?Yamaki Melon Nutrition Solution??m_N:m_P:m _K5:1:6?;Test ?: Test of nutrient solution with different proportions: set 5 nutrition levels T1?m_N:m_P:m _K3:1:6?,T2?Yamazaki formula control??m_N:m_P:m _K5:1:6?,T3?m_N:m_P:m _K5:1:7?,T4?m_N:m_P:m _K5:1:8?,and T5?m_N:m_P:m _K3:1:8?,and use Water and fertilizer integrated drip irrigation.The differences of plant growth,photosynthetic physiology,plant nutrient accumulation,yield,and quality under different nitrogen and potassium content water-soluble fertilizers and different proportions of nutrient solution were studied,and a formula for water-soluble fertilizers suitable for melon substrate bag cultivation was selected.At the same time,according to the characteristics of the growth and development of the oriental melon,the characteristics of the water-soluble fertilizer formula were further optimized.Based on this,the changes of sugar metabolism-related enzymes,nitrogen metabolism-related enzymes in roots and leaves,the activity of potassium channel absorption transport enzymes and the expression of key enzyme genes for nitrogen and potassium absorption and metabolism were studied.The results show:1.In water-soluble fertilizer experiments with different nitrogen and potassium contents in melon,different formula water-soluble fertilizers showed different growth advantages.The chlorophyll content,net photosynthetic rate and intercellular CO₂ concentration of the leaves treated by P1 were the largest among the treatments.Plant height and stem diameter of P2 treatment were significantly better than those of control and other treatments.P3 treatment had the highest vitality.In terms of yield and quality indicators,P1 treatment had the highest single fruit quality,single plant yield,soluble solids,Vc,soluble protein,soluble sugar content,and sugar-acid ratio.9.75%.Moreover,the total N and K accumulations in plants were highest in P1 treatment.2.In different nutrient solution experiments,the root vigor and photosynthetic capacity of T1 and T5 treatments are significantly higher than those of T2,T3 and T4 treatments.At the 16 th day of treatment,the plant height,stem diameter,leaf chlorophyll a and chlorophyll b content of T1 and T5 treatments were significantly higher than those of T2 treatment.It showed that proper nitrogen and potassium reduction during fruit development can meet the melon's later growth requirements.Yield and fruit weight of melon were significantly increased in T1 and T5 treatments compared with T2 treatment.The glucose content of melon fruits in T5 treatment was not significantly different from that in T1 treatment,and significantly higher than that in T2,T3 and T4 treatments.There was no significant difference in fructose content in fruits between different treatments.Compared with T2 treatment,the sucrose content in T1 and T5 treatments increased significantly by 31.28% and 36.94%,respectively.The fruit quality index showed T5> T1> T2> T3> T4.The nutrient accumulation in plant roots,stems and leaves was highest in T1 and T5 treatments,and there was no significant difference between the two.3.In the experiment with different nutrient solutions,at the 16 th day of treatment,the sucrose phosphate synthase?SPS?activity in melon fruits was significantly increased by 11.63% compared with T2 treatment,and T4 treatment was significantly reduced by 18.88% compared with T2 treatment.Treatment 24 At d,the sucrose synthase?SS?activity in T1 treatment was significantly higher than that in T2 treatment by 9.98%,and the SS activity in T4 treatment was significantly lower than that in T2 treatment by 24.94%.The activities of acid invertase?AI?and neutral invertase?NI?in fruits showed a decreasing trend during the treatment.On the 16 th day of treatment,the activities of AI and NI in T1 treatment were significantly higher than those in T4 treatment.The nitrogen metabolism-related enzyme activity in leaves and roots of T1 treatment was also significantly higher than that of T4 treatment,and the difference increased with the extension of treatment time.H⁺/K⁺-ATPase and Na⁺/K⁺-ATPase activities in leaves and roots were not significantly different between T1 and T2 treatments,but H⁺/K⁺-ATPase activity was significantly higher on T1 and T2 treatments than on T4 treatment on the 16 th day.Na⁺/K⁺-ATPase activity in leaves and roots was not significantly different in T1 and T2 treatments,while Na⁺/K⁺-ATPase activity in roots was on the 8th day,and Na⁺/K⁺-ATPase activity in leaves was on the 32 nd day.T2 treatment was significantly higher than T4 treatment.There was no significant difference in Ca²⁺-ATPase activity in T1 and T2 treated leaves,and Ca²⁺-ATPase activity in roots was significantly higher in T1 and T2 treatments than in T4 treatment from the 8th day of treatment.The trend of Mg²⁺-ATPase activity was similar to that of H⁺/K⁺-ATPase.4.Under different nutrient solution treatments,the expression level of nitrate reductase gene Cm NR in T1 treatment was significantly up-regulated in the early stage of fruit development,while the expression levels of glutamine synthetase and glutamate dehydrogenase Cm GS,Cm GDH1 and Cm GDH2 were changed.The law is not significant.The expression of Cm AKT1 in the rectifier K⁺ channel gene in the melon roots of T4 treatment was significantly higher than that of T1 and T2 treatments,and there was no significant difference between T1 and T2 treatments.The expression of Cm SKOR in K⁺ uptake genes on the externally rectified K⁺ channel first increased and then decreased.After 8 days of treatment,the expression of Cm SKOR in the roots of T1 treatment was significantly higher than that of T4 and T2 treatments,and at 32 days,T1 The expression of Cm SKOR decreased after treatment.In summary,P1 treatment of water-soluble fertilizer can significantly improve the yield and quality of melon fruit,which is suitable for application in the fruit and water period.T1 and T5 treatments did not differ significantly in terms of yield quality indicators.The ratio of nitrogen,phosphorus,and potassium in the T1 nutrient solution is more conducive to the absorption of nitrogen and potassium by the root system and transportation to the ground,and promotes the plant's nitrogen metabolism and the formation of photosynthetic products.Combined with the requirements of melon fruit-reducing fertilization,under the conditions of integrated bag-water-fertilizer cultivation,T1 nutrient solution is more conducive to achieving high-quality and high-yield melon,and at the same time,it can achieve appropriate nitrogen fertilizer reduction.