Effects Of Different Environmental Factors On Growth And Physiological Effects In Spinach

Spinach(Spinacia oleracea L.)is a typical long-day plant,the early and late flowering stage and the ratio of dioecious plants are closely related to the purity and yield of hybrid seed production.Factors such as temperature,light and hormones are important factors regulating plant flower bud differentiation and flowering.At present,there are few studies on the effects of light quality,photoperiod and hormones on the growth and sex differentiation of spinach,and the regulation and control of spinach bolting and flowering are underutilized.In this study,spinach was treated with red and blue ratio,photoperiod and hormones.By measuring growth indicators,nutrition indicators,and surveying flowering time,and observing its sexual differentiation,combined with MADS-box gene expression analysis,we explored the growth and nutrition of spinach with light and hormone treatment.The main research results are as follows:1)Red and blue ratio treatments showed that spinach had significantly higher growth indexes such as plant height,plant width,leaf length,leaf width,and leaf number than the white light control.Among them,R4B1 and R5B1 treatments were more conducive to the growth of late-bolting spinach lines SP75 and GS6;while R5B1 and R3B1 treatments were more favorable to the growth of non-late-bolting spinach lines SP73 and GS8.In addition,red and blue light treatment significantly increased the content of vitamin C,soluble sugar and soluble protein in spinach,and reduced the content of nitrate nitrogen and ?-carotene in spinach.At the same time,the red and blue light treatment promote spinach earlier bolting and flowering.Among them,R4B1 and R5B1 significantly promoted earlier bolting and flowering,and induced female plants to produce male flowers.Under R4B1 conditions,the bolting and flowering time were 13.3 d and 32.7 d,respectively.Under R5B1,the spinach bolting and flowering time were 15.2 d and 21.0 d,respectively.2)Photoperiod treatment showed that spinach had positive effect on plants size,plant height and leaf numbers.After long daylength treatment,the content of vitamin C,soluble sugar and soluble protein in spinach leaves were significantly higher than those in control,and the content of nitrate was lower than that in control.At the same time,the bolting and flowering time was significantly advanced after long light treatment.For late-bolting lines,the spinach bolting and flowering time were significantly earlier 40.2 d and 72.1 d,after long light treatment,respectively;for non-late-bolting lines,the spinach bolting and flowering time were significantly earlier 7.7 d and 52.1 d,after long light treatment,respectively.3)The gibberellin treatment showed that GA3 has a positive effect on the growth of spinach.The nutrient content in leaves of spinach changed significantly,but different varieties had different effects on gibberellin.With 50 and 100 mg/L gibberellin,the bolting and flowering time of late-bolting spinach were 32.6 d and 4.5 d,respectively;for the non-tolerant cultivars,the bolting and flowering time were 8.7 d and 16.7 d,respectively.In addition,this study showed that the plant size and plant height of spinach became smaller after ethephon treatment.There was no significant effect on bolting and flowering time,and sexual differentiation of spinach during flowering.Besides,it inhibits growth and even promotes spinach leaf senescence at high concentrations.4)There are 52 MADS-box proteins in spinach were identified,including 16 Type I MADS-box genes,and 36 Type II MADS-box genes,and there were more introns in Type II MADS-box gene and 14 Type I MADS-box genes were intronless,and the number of conserved motifs in type I MADS-box proteins was more than that in Type II MADS-box proteins.There were a lot of light-induced and responsive cis-elements in the promoter region of the MADS-box genes in spinach.All detected genes were lower expressed in roots,and most genes were high expressed in rosette petioles,bolting leaves,bolting petioles,stems,male flowers and female flowers,among which So MADS26 has higher expression in bolting leaves and bolting petioles,and So MADS33,So MADS49 and So MADS51 have higher expression in male and female flowers.Besides,the expression level of So MADS-box genes was induced by light quality treatment,and the expression abundance of So MADS22,So MADS28,So MADS32 and So MADS49 was higher,especially under R4B1,R5B1 and R6B1 treatments.