Research On Optimization Of Management Mode In Intercropping And Effect On The Growth And Development For Aeroponics Lettuce

As a typical soilless cultivation method,aeroponics effectively solve the traditional mode between the absorption of water and nutrients from nutrient solution by plant roots and the oxygen supply by roots.The method has the advantages of water saving,increasing yield and efficiency,which is the development direction of vegetable cultivation technology in future facility agriculture.However,the high of nitrate content are still facing problems in leafy vegetables.In order to solve this problem,this paper seeks an effective way to improve the yield and quality of vegetables by the perspective optimization of management mode.The paper took lettuce?Lactuca sativa L.?as the research object,based on previous findings in our group.Intercropping cultivation system was built between lettuce and cherry radish in aeroponics.The orthogonal test was utilized to study the influence of intercropping ratio,phased management of nutrient solution concentration and the time of pre-harvest light supplementation on target plants.And then the optimal cultivation management mode was selected and verified.Meanwhile,the optimal cultivation management mode was evaluated.Then the various cultivation management modes,including in the optimal cultivation management mode,which were explored on the dynamic state of growth,quality formation and photosynthetic physiological characteristics in lettuce.The aim is to establish a theoretical foundation for the soilless cultivation system of vegetables.The research results are as follows:1.Selection of the optimal cultivation management modeLettuce were as object under the intercropping aeroponics system with cherry radishes.The repeat orthogonal test of 3 factors and 3 levels were enforced under the management mode of the intercropping aeroponics system in spring and fall.The orthogonal test was utilized to study the influence of intercropping ratio,phased management of nutrient solution concentration and the time of pre-harvest light supplementation on target plants.The orthogonal optimization experiment of L₉?3⁴?orthogonal table was designed for the yield and quality of lettuce.In this paper,the results showed that the optimal combination of factors in the cultivation management mode was as follows:the intercropping ratio of lettuce and cherry radish was 2:1;the nutrient solution was supplied by 1/2 standard concentration in the early stage and in the week before harvest,and standard concentration in the middle stage;and the time of pre-harvest light supplementation was 48 h.2.Verification of cultivation management modeThe comparative experiments were carried out in various cultivation management modes,including monoculture and intercropping.The results showed that the FW,DW,max leaf area of lettuce increased by 36.82%,42.34%,31.69%,respectively in the optimal cultivation management mode,compared with the traditional management mode.The soluble sugar and soluble protein increased by49.48%,24.84%,respectively and the NO₃^-decreased by 41.97%.The energy input of cultivation system were all decreased in the optimal cultivation management mode,compared with the other experimental groups and it was reduced by a maximum of42.82%in biomass per unit area.Meanwhile,the total output value of cultivation system were all increased it was improved by a maximum of 50.67%in per unit area.Therefore,the results indicate that the optimal cultivation management mode has certain advantages on reducing energy consumption and improving economic benefits in the cultivation system.3.Research on the effects of cultivation management modes on the growth and quality of lettuceIn view of the traditional management mode?T1?,the phased management of nutrient solution concentration?T2?,and the optimal cultivation management mode?T3?,the experiments were carried out on the dynamic characteristics for the growth and quality of lettuce.The results showed that the growth indexes of lettuce were all increased in the T2 and T3 when harvested,compared with the T1.The most improvement in T3 was 35.29%in the maximum leaf area of lettuce.The leaf fresh weight?production?was increased by 16.64%and 20.14%,respectively,from T2 and T3.The soluble sugar,soluble protein and vitamin C of lettuce were all increased and the soluble sugar in T3 was increased the most by 81.74%.The nitrate in lettuce leaves was also decreased and decreased by 26.63%in T3.Therefore,T3 was as the optimal cultivation management mode,which has an excellent effect on the growth and quality of lettuce.4.Research on the effect of cultivation management modes on photosynthesis of lettuceIn view of the traditional management mode?T1?,the phased management of nutrient solution concentration?T2?,and the optimal cultivation management mode?T3?,the experiments were carried out on the dynamic characteristics for photosynthesis of lettuce.The results showed that T2 and T3 mode had obvious advantages in photosynthetic physiological characteristics of lettuce during its growth and development.The Pn of lettuce in T1 mode was lower at the 10 d to 15 d due to restriction of non-stomatal factor,while the Pn of lettuce was decreased at the 20 d to30d due to insufficient CO₂ in intercellular space caused by stomatal restriction.On the 20^thh day of transplanting,the Pn of lettuce almost reached the maximum of the whole growth stage under the three cultivation management modes.On the 25^thh day of transplanting,the Fv/Fm and the?_PS?of lettuce reached the maximum value of the whole growth stage under the three cultivation management modes.