Effects Of Root Zone Irrigation On Growth,development And Quality Of Muskmelon In Substrate Culture

Melon is one of the important cash crops in Ningxia,but the increasing shortage of water resources and the contradiction between supply and demand limit its productivity.According to early studies,alternate root zone irrigation(APRI)can adjust the optimal stomatal opening of leaves by using the water stress signal generated by roots,reduce the ineffective evaporation loss and total irrigation amount,improve the water absorption capacity of roots and the utilization rate of soil nutrients,and achieve the water-saving effect without sacrificing the accumulation of photosynthetic products.In this study,two experiments were designed.the first experiment,taking muskmelon variety ’ansha’as the research object,set up two factors and three levels of completely random experiment,namely,alternating irrigation frequency and irrigation volume,the frequency of continuous irrigation liquid supply was changed alternately:C1:1 day,C2:3 days,C3:5 days,and the liquid supply volume was t1:400 ml/plant/day,T3:600 ml/plant A total of 9 processes are set up.Experiment 2:Taking the melon variety’Jinshan’ as the research object,a completely random experiment with two factors and three levels of different irrigation methods and irrigation volume was set up.The water supply methods were:F:1/2 fixed root irrigation,H1:alternate irrigation(for three consecutive days),H2;Alternate irrigation(3 days/time);The liquid supply:T1:400 ml/plant/day,T2:600 ml/plant/day,T3:800 ml/plant/day,with 9 treatments.The experimental results show that:(1)Different irrigation methods and irrigation amounts influenced root growth.The total root length,root surface area,root volume and root average diameter of C2T3 and H1T3 reached the maximum in two experiments.It indicated that increasing irrigation amount was more beneficial to the growth of plant roots.Three-day alternate irrigation,with three-day alternate frequency,makes the root system undergo suitable drought exercise,and the endogenous hormones produced promote its growth,which is more conducive to the development and growth of plant roots.It is a suitable alternate irrigation method for root zone irrigation.(2)The Fv/Fm,Qp and Npq were higher in the two experiments under three-day alternate irrigation,but Fv/Fm,Qp and Npq showed different differences under the influence of irrigation amount.At the same time,the plant height and stem diameter of three-day alternate irrigation were significantly higher than those of other treatments,and the relative growth rate was larger and the growth was faster.The results indicated that under the premise of sufficient water supply,alternate irrigation in root zone once every three days can effectively reduce the intensity of photoinhibition,stimulate the compensation effect and self-photoprotection function,and inhibit the decomposition of related photosynthetic pigments,which is beneficial to the secondary growth of plants.Therefore,alternating irrigation once every three days is an effective way to improve plant growth.(3)Compared with conventional irrigation,alternate irrigation in different root zones did not affect melon yield,but increased water use efficiency.Increasing irrigation amount makes better use of the increase of melon yield.Under the same irrigation amount,alternating irrigation once every three days significantly improves melon yield and water use efficiency.Therefore,it is considered that the treatment of 800 ml/plant/day of alternate irrigation once every three days in root zone can be used as the best irrigation combination mode to increase melon yield.(4)Compared with traditional irrigation methods,alternate irrigation in different root zones significantly increased soluble solids,Vc content and soluble sugar in melon fruit(P<0.05).Appropriate water deficit can improve the quality index of muskmelon,and the irrigation method of alternating irrigation once every three days is more conducive to the improvement of fruit quality.Therefore,the treatment of alternating irrigation once every three days in root zone at 400 ml/plant/day can be regarded as the best irrigation combination mode to improve the comprehensive quality of muskmelon.To sum up,irrigation mode and irrigation amount have mutual influence.In melon production,combined with the actual growth situation,under the condition of ensuring reasonable irrigation amount,three-day alternate irrigation by root irrigation is an effective measure to promote melon growth and quality improvement.