工厂化条件下氮处理对奶油生菜的生长及生理影响

通过水培试验研究不同氮处理(5 mmol·L~(-1)NO_3~--N、10 mmol·L~(-1)NO_3~--N和5 mmol·L~(-1)NO_3~--N+5 mmol·L~(-1)NH_4~+-N)对奶油生菜生长和生理特性的影响。研究结果表明,35 d后,总氮浓度相等时,NH_4~+-N抑制奶油生菜生长,该处理叶面积、株高、地上鲜重、地上干重、地下鲜重和地下干重分别降低78.2%、60.4%、87.0%、81.3%、80.1%和87.5%(P0.05),此外,两者的生理活性如根系活力、可溶性蛋白质、超氧化物歧化酶活性和硝酸还原酶活性均有显著性差异(P0.05)。与10 mmol·L~(-1)NO_3~--N(12.89 g)相比,5mmol·L~(-1)NO_3~--N(8.90 g)处理奶油生菜生物量稍微有所降低,叶面积、根长和地下干重分别降低48.1%、50.3%和37.5%(P0.05),而叶可溶性糖含量和花青素相对含量分别升高67.5%和51.9%(P0.05),而对NO_3~--N的吸收两者的比值在第21 d达到最大值,后者是前者的3.15倍。研究结果表明奶油生菜是喜硝蔬菜,且生菜的硝态氮适宜浓度前期(前21 d)为高浓度(10 mmol·L~(-1)),以便促进奶油生菜生长,后期(21 d后)可改为低浓度(5 mmol·L~(-1))以提高品质。

Effects of different nitrogen on growth and physiological response of Lactuca sativa L.var.ramosa Hort with hydroponics in a plant factory

The effects of different nitrogen treatments(5 mmol·L NO-3-N,10 mmol·L-1 NO-3-N,5 mmol·L-1 NO-3-N+5 mmol·L-1 NH+4-N)on the growth and physiological characteristics of Lactuca sativa L.var.ramosa Hort were studied.The results showed that after 35 days,NH4 + -N inhibited the growth of lettuce with the same nitrogen concentration.The leaf area,plant height,aboveground fresh weight,aboveground dry weight,underground fresh weight and underground dry weight decreased by 78.2%,60.4%,87.0% ,81.3%,80.1% and 87.5% respectively(P<0.05).In addition,there were significant differences in their physiological activities such as root activity,soluble protein,superoxide dismutase activity and nitrate reductase activity(P<0.05).Compared with the treatment of 10 mmol·L-1 NO-3-N(12.89 g),the biomass of lettuce reduced slightly with the treatment of 5 mmol·L-1 NO-3-N(8.90 g),and the leaf area,root length and underground dry weight decreased by 48.1 %,50.3% and 37.5% respectively(P < 0.05),but the content of soluble sugar and anthocyanin increased by 67.5% and 51.9% respectively(P<0.05),while the ratio of NO-3-N uptake reached the maximum on the 21st day,which was 3.15 times of the former.Our results showed that the creamy lettuce was a nitrate favorite vegetable,and the optimum concentration of nitrate nitrogen in lettuce was high(10 mmol·L-1)in early prophase(21 days)in order to promote the growth of butter lettuce,but later(21 days)low concentration(5 mmol·L-1)was better to improve quality.