| Light is an important environmental factor that affects the growth and development of plants.In facility cultivation,the shortage of light severely affects the growth and development of vegetable crops and the formation of quality.There are more use of artificial light supplement on production to improve the light conditions inside facilities.Past research more concentrated on the influence of light quality and light intensity on vegetable growth and development,but the research about different ways of supplementing light is less.To evaluate the effect of supplementary LED blue light e nergy and time bucket on growth,quality and health-promoting compounds in pak-choi(Brassica campestris ssp.chinensis var.communis),supplementing blue light 10 days before harvest of pak-choi.There were two experiments.(1)Different supplementing light energy: supplementing blue light 6 :00-18:00,CK : 0 mol/d;supplementing light 1 h after 1 h,the light energy for 0.78 mol/d;supplementing light 2 h after 1 h,the light energy for 1.04 mol/d;continuous supplementing light,the light energy is 1.56 mol/d.(2)Different supplementing light session: on the basis of light energy for 0.78 mol/d,CK: no supplementing light;light session in the morning and evening(6:00-8:00,18:00-20:00);light session in morning and afternoon(9:00-11:00,15:00-17:00);T3: intermittent supplementing light during the day(19:00 to 7:00,supplementing light 30 min after stop 30 min).Main research results are as follows: 1.Effect of different supplementing light energy on growth of pak-choi.(1)When supplementing blue light,the two types of cabbages were significantly higher in biomass than CK The biomass of two pak-choi are greatest in T1 treatment(light energy is 0.78 mol/d).The content of total chlorophyll in the red-leaf pak-choi is highest in T1.There was no significant difference about chlorophyll content in green-leaf pak-choi.(2)Compared with CK,the complementary light processing significantly increased the VC content of two kinds of pak-choi.The content of soluble protein in pak-choi was not significantly affected by the treatment of light.As the amount of supplementing blue light increased,the soluble sugar content gradually decreased,and the T3 was significantly lower than CK.As the amount of light increased,the nitrate content gradually decreased,and two kinds of pak-choi with the lowest nitrate levels in T3 treatment.(3)Compared with CK,supplementing blue light significantly promoted the content of total phenol and flavonoids,carotenoids and anthocyanins in two pak-choi,and there is no significant difference between three light treatments.(4)Supplementing blue light promote the absorption of total nitrogen,phosphorus,potassium,calcium,magnesium ion in aboveground red-leaf pak-choi.T2 treatment with the highest levels of nitrogen,and T3 treatment with the highest levels of calcium,but lowers the content of zinc and iron.Supplementing blue light promote the absorption of nitrogen,phosphorus,potassium,magnesium,zinc and iron in green-leaf pak-choi,reduce the absorption of calcium.Therefore,comprehensive the point of study result and energy expenditure,supplementing light energy is 0.78 mol/d(T1 treatment)is the best scheme for artificial supplementary blue light in production.2.On the basis of light energy for 0.78 mol/d,the effect of different supplementing light session on pak-choi:(1)The amount of biomass of both types of pak-choi in supplementing light treatment was significantly higher than the comparison.There was the highest amount of biomass under T3 in red-leaf pak-choi;The treatment of T1 and T3 was the most favorable for the accumulation of biomass in green-leaf pak-choi.(2)The amount of total chlorophyll content of both types of pak-choi in supplementing light treatment was significantly higher than the comparison.In T3 treatment,the content of total chlorophyll in red-leaf pak-choi is highest;supplementing light treatments all significantly increased the pigment content in green-leaf pak-choi,and there was no significant difference.(3)Compared with CK,the treatments of different light time periods significantly increased the VC and soluble sugar content of two kinds of pak-choi.There were the highest levels of soluble sugar and VC in T3 treatment,with the lowest nitrate content.(4)Compared with CK,the treatments of different light time periods significantly increased total phenol,flavonoids,anthocyanins,total sulphur.In T3 treatment,the content of total phenol,flavonoids,total sulphur,DPPH,and FRAP are the highest level in red-leaf pak-choi.In T1 treatment,the content of total phenol and coloradin,the DPPH reached the maximum in green-leaf pak-choi,while T3 treatment the total sulfide,and the carotenoid content reached the maximum in green-leaf pak-choi.(5)Compared with CK,T3 treatment promoted the absorption of phosphor,calcium and magnesium elements in red-leaf pak-choi.Green-leaf pak-choi had the highest absorption of phosphorus,calcium,zinc and iron in T1 while T3 treatment had the highest levels of potassium in green-leaf pak-choi.To sum up,supplementing blue light energy of 0.78 mol/d and supplementing blue light during the day(19:00 to 7:00,supplementing light 30 min after stop 30 min)were best for the growth and development of pak-choi,and can be used as reference solution on pak-choi cultivation in production. |
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