Screening Study On Coconut Peat Compound Substrate,Nutrient Solution Formula And Concentration For Tomato Plug Seedling

In recent years,with the rapid development of the tomato industry in the Xinjiang region,seedling transplanting has become an important part of the tomato cultivation process.As seedling quality has a greater impact on vegetable plant growth,yield and commercial quality,and seedling quality depends on the root growth environment and nutrient supply is sufficient or not;grass charcoal as one of the traditional seedling substrate,seedling effect is better,but it is a non-renewable resource and expensive,coconut coir as a renewable resource is now used in some vegetable seedling nursery.In order to improve the quality of seedlings and to explore a technical system for tomato seedling raising in cavity trays under Xinjiang climate conditions,this paper takes’Mao Fan 812’tomato as the research object,and studies two important factors in the form of seedling substrate and nutrient supply in the form of cavity trays in order to screen out a coconut bran composite substrate formulation,nutrient solution formulation and nutrient solution concentration in winter and spring that is suitable for tomato seedling growth.The main findings are as follows.（1）Different coconut coir substrate ratios had an effect on the growth,leaf physiological activity and photosynthetic characteristics of tomato seedlings.Treatment T3（grass charcoal:coco coir:vermiculite:perlite=2:2:2:2）had the highest seedling emergence rate of 97.22%.Seedlings in the T1treatment（grass charcoal:coco coir:vermiculite:perlite=3:1:2:2）had the highest plant height of 14.44cm.Seedlings in the T6 treatment（grass charcoal:coconut bran:vermiculite:perlite=0:5:2:1）had the highest chlorophyll content,root to crown ratio and G value of 1.38 mg·g^-1,0.26 and 15.03 mg·d^-1,respectively.The maximum leaf area,soluble sugar content,transpiration rate,root vigour,whole plant dry weight and seedling strength index of seedlings in the T9 treatment（grass charcoal:coconut bran:vermiculite:perlite=0:3:2.5:2.5）were the highest at 35.91 cm²,0.15 mg·g^-1,9.59 mmol·m^-2·s^-1,11.44 g·（g·h）^-1,0.75 g and 0.37.Using principal component analysis and affiliation function to synthesize each trait index of seedlings and calculate the composite score,it was found that T9>T8>T7>T5>T6>T1>T4>T2>CK>T3,therefore,the composite substrate formulation of grass charcoal:coconut bran:vermiculite:perlite=0:3:2.5:2.5（T9）can be used as seedling substrate for tomato cavity tray seedlings.（2）There are differences in the effectiveness of different formulations of nutrient solutions for tomato seedling development.Tomato seedlings watered with Arnon and Hoagland tomato formula nutrient solutions had the fastest growth rates,the highest accumulation of assimilates and the highest root vigour,G-value and robustness index of 9.83 g·（g·h）^-1,6.487 mg·d^-1 and 0.144,respectively.The highest chlorophyll content of 3.35 mg·g^-1 was recorded in seedlings grown by watering the Japanese Yamazaki tomato formula.The physiological activity of tomato seedlings watered with 1.8 concentration units of the South China Agricultural University tomato formula nutrient solution was high.Analysis of the correlation between major elements and seedling indicators showed that NO₃^-was positively correlated with the robustness index and G value,NH₄⁺with root to crown ratio,and K⁺with plant height and leaf area.Using principal component analysis and affiliation functions,the seedlings were analysed for each trait and a composite score was calculated.The highest composite score was obtained for the Arnon and Hoagland tomato formulations,so the Arnon and Hoagland tomato formulations could produce strong seedlings when watered with coir:vermiculite:perlite=3:2.5:2.5（volume ratio）as the seedling substrate.The Arnon and Hoagland tomato formulations can therefore produce strong seedlings when watered with Arnon and Hoagland tomatoes as a substrate.（3）For fall and winter seedlings,the nutrient solution with a concentration of 1.2 g·L^-1 was irrigated from 10 d to 25 d after sowing,the nutrient solution with a concentration of 2.2 g·L^-1 from 25 d to 40 d after sowing,and the concentration of 3.2 g·L^-1 50 d after sowing nutrient solution,the plant height,maximum leaf area,soluble sugar content and root activity of tomato seedlings were the highest,which were 11.89 cm,28.91 cm²,0.087 mg·g^-1 and 10.09 g·（g·h）^-1,respectively;The three stages of seedling growth were irrigated with 0.8 g·L^-1,1.8 g·L^-1,2.8 g·L^-1 nutrient solution,respectively.The soluble protein content,chlorophyll content and net photosynthetic rate of the leaves of the seedlings were the highest,which were 6.45 mg·g^-1,3.09 mg·g^-1 and 10.55μmol·m^-2·s^-1,respectively.At the same time,the antioxidative enzyme activities of the seedlings more active.During the three stages of seedling growth,nutrient solutions with concentrations of1 g·L^-1,2 g·L^-1,3 g·L^-1 were respectively irrigated,and the seedling stem diameter,number of leaves,stomatal conductance,and intercellular CO₂ concentration,transpiration rate,G value and seedling strength index were the largest,which were 2.37 mm,4.60 pieces,0.04μmol·m^-2·s^-1,229.41μmol·mol^-1,1.77mmol·m^-2·s^-1,3.04 mg·d^-1 and 0.054 respectively.Through a comprehensive analysis of the growth,physiological activity,photosynthetic characteristics and accumulation of assimilates of tomato seedlings,It was concluded that the seedlings irrigated with nutrient solution concentration of 1 g·L^-1,2 g·L^-1 and 3 g·L^-1 in three stages were more robust.（4）When planting in spring,The nutrient solution with a concentration of 1 g·L^-1 was irrigated from 10d to 25 d after sowing,the nutrient solution with a concentration of 2 g·L^-1 was irrigated from 25 d to 40 d after sowing,and the concentration of 3 g·L^-1 was irrigated 50 d after sowing nutrient solution,the plant height,stem diameter,maximum leaf area,number of leaves,soluble protein,chlorophyll content and photosynthetic rate of tomato seedlings were 16.23 cm,3.73 mm,39.03 cm²,6.67 pieces,9.52 mg·g^-1,2.68mg·g^-1 and 14.60μmol·m^-2·s^-1 respectively;During the three stages of seedling growth,nutrient solutions with concentrations of 1.2 g·L^-1,2.2 g·L^-1,3.2 g·L^-1 were respectively irrigated,and the root activity,whole plant fresh weight,and whole plant dry weight were,G value and seedling strength index were the highest,which were 3.82 mm,30.58 g·（g·h）^-1,6.90 g,0.83 g,16.62 mg·d^-1 and 0.28,respectively.Through a comprehensive analysis of the growth,physiological activity,photosynthetic characteristics and accumulation of assimilates of tomato seedlings,it was concluded that the nutrient solutions of 1 g·L^-1,2 g·L^-1,3 g·L^-1 were suitable for the growth of tomato seedlings in spring in three stages respectively.