不同光周期下叶面喷施纳米硒对生菜生长和品质的影响

Effects of nano-Se foliar spraying and photoperiod on lettuce growth and quality

本试验以‘意大利耐抽薹’生菜为试材,采用水培法,设置12 h/12 h(对照)、16 h/8 h、20 h/4 h 3个光周期和叶面喷施0μmol∙L^(-1)、24μmol∙L^(-1)和48μmol∙L^(-1)纳米硒,两者完全随机组合,共9个处理,以此探究两者对生菜生长和品质提升的交互作用,并筛选出适宜生菜生长的最适处理,为植物工厂在光环境下施加纳米硒提供理论依据和技术参考。结果表明:1)16 h/8 h光周期叶面喷施48μmol∙L^(-1)纳米硒处理对生菜株高、地上部鲜重、地下部鲜重和根系活力的促进效果较佳。2)20 h/4 h光周期叶面喷施48μmol∙L^(-1)纳米硒处理对生菜光合色素含量的促进效果最佳。3)16 h/8 h光周期处理生菜中可溶性糖、K、Na、Fe含量显著增加,硝酸盐含量显著下降(P<0.05)。20 h/4 h光周期处理有利于提升可溶性蛋白质、还原糖含量,但较长的光照处理不利于生菜中氨基酸、Ca、Mg、Zn、Fe、Mn含量提高,甚至出现抑制效果。与对照(12 h/12 h光周期)相比,16 h/8 h、20 h/4 h光周期处理均有利于生菜品质的提升,而且叶面喷施纳米硒后进一步提升了生菜品质。此外,本试验通过对生菜生长指标和部分品质指标采用主成分分析,并对其综合排序,结果表明16 h/8 h光周期下叶面喷施48μmol∙L^(-1)纳米硒对生菜生长和品质的提质效果最佳。

Nano-Se(nano-selenium)and illumination length are two important factors those are used for improving vegetable nutritional quality and yield.Although the effects of exogenous Se and photoperiod on the growth and quality of lettuce are well-studied separately,there are few studies reporting on the combination effect of these two factors.As such,in this study,we assessed the interaction of nano-Se and photoperiod on the growth and quality of lettuce;in addition,we derived the optimal combination of photoperiod and nano-Se concentration for the growth of lettuce,with the aim of providing a theoretical basis and technical starting point for plant factories to apply nano-Se under lighting systems.To accomplish this,we used‘Italian Bolting-resistant’lettuce(Lactuca sativa L.)in a hydroponics system with three photoperiods(light/dark:12 h/12 h,P1;16 h/8 h,P2;or 20 h/4 h,P3).In addition,the lettuce leaf surfaces were treated with a spray containing 0μmol∙L^(-1)(N1),24μmol∙L^(-1)(N2),or 48μmol∙L^(-1)(N3)of nano-Se.The two factors were randomly combined,resulting in a total of nine photoperiod and nano-Se treatment combinations.The results revealed that first,the P2N3 treatment had a positive effect on plant height,aboveground fresh weight,underground fresh weight,and root activity.The P2N2 treatment resulted in plant height to increase significantly(P<0.05)by 13.16%and 21.74%when compared to the P1N2 and P3N2 treatments,respectively;and the P2N3 treatment resulted in the lettuce fresh weight to increase by 56.13%and 15.14%when compared to the P1N3 and P3N3 treatments,respectively,but the difference was not significant.Second,prolonging the light period increased the chlorophyll content of the lettuce,with the highest chlorophyll a and chlorophyll b contents being found in the P3N3 treatment,whereas the highest carotenoid content was found in the P3N2 treatment.Third,the soluble sugar,K,Na,and Fe contents in the lettuce increased significantly under P2 treatment,whereas the nitrate content decreased significantly(P<0.05).The P3 treatment increased the soluble protein content and reduced the sugar content.But the longer illumination period was not conducive to an accumulation of amino acids,Ca,Mg,Zn,Fe,nor Mn in the lettuce,instead,inhibitory effects were displayed.The P2N3 treatment resulted in an increased content of various amino acids in the lettuce.Interestingly,the P3 treatment in combination with nano-Se foliar spraying resulted in an increase in the amino acid content of the lettuce,however,the amino acid content decreased with an increasing nano-Se concentration.Compared with P1,the P2 and P3 treatments improved the lettuce quality,which was further improved by nano-Se leaf spraying.Finally,the principal component analysis on the growth and quality indices of the lettuce showed that 48μmol∙L^(-1)of nano-Se foliar spraying(i.e.,the N3 treatment)under a 16 h/8 h(i.e.,the P2 treatment)photoperiod resulted in the greatest improvement to lettuce growth and quality.