| Non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino) belongs to the cruciferae brassica, with rich nutrients of vitamins, proteins and mineral elements such as calcium, phosphorus and potassium. Purple non-heading Chinese cabbage is a new kind of color vegetables, with gorgeous color, instant edibility as well as rich nutrition. In addition, purple non-heading Chinese cabbage contains plenty of anthocyanin, and anthocyanin has much health functions to human body. But when it was cultivated under improper environmental conditions, the content of anthocyanin would reduce, and their nutritional value would be further affected. The research concentrate on the how environmental conditions affect the leaf color of purple non-heading Chinese cabbage. This work has not been reported before, here we use ’Ziguan No.1’ as experimental materials and study the rule how the leaf color of purple non-heading Chinese cabbage changes under different environmental conditions, in order to provide scientific basis for the production of purple non-heading Chinese cabbage.This article explores the effects of KH2PO4 foliar spraying with different concentrations (3‰,9‰,20‰ and CK) and shading (light transmittance 60%,75% and CK) on leaf color and related physiological indexes of purple non-heading Chinese cabbage. The main points and the results are as follows:1. The leaf color related physiological changes of purple non-heading Chinese cabbage sprayed with KH2PO4 of different concentration of were studied in this experiment.Four levels were set according to the concentration of a KH2PO4 solution:3%o (as K1), 9‰ (as K2),20‰(as K3) and CK (spraied with distilled water). Samples were taken every 10 d to examine the contents of anthocyanin, chlorophyll, carotenoid, soluble sugar and soluble protein in purple non-heading Chinese cabbage leaves.The results showed that the contents of chlorophyll and carotenoid increased, so did the contents of soluble sugar, soluble protein, and anthocyanin increased then the leaf color of purple non-heading Chinese cabbage became deeper with KH2PO4 spraying treatments. The 9%o KH2PO4 treatment was most beneficial to improve the anthocyanin biosynthesis and accumulation of soluble sugar and soluble protein.2. Effects of shading treatments on leaf color expression of purple non-heading Chinese cabbage.Three gradients were set according to the shading rate:75%,60% and CK (nature light). Samples were taken every 10 d to examine the contents of anthocyanin, photosynthetic pigment, soluble sugar and soluble protein in purple non-heading Chinese cabbage leaves.The results showed that under the condition of different shading, the photosynthetic pigment content increased with the decreasing of light intensity. The content of photosynthetic pigment is the most under 75% shading rate; under the nature light, content of cyanine glycosides, soluble sugar and soluble protein were significantly higher than those of other treatments, and showed a positive-correlation among the three indexes, they all decreased with the increasing of shading rate. Strong light, therefore, helps the accumulation of anthocyanin, soluble sugar and soluble protein synthesis in purple non-heading Chinese cabbage leaf, but it is not good for chlorophyll accumulation. Leaf color becomes shallow under shading treatments; Nature light treatment can promote the biosynthesis of soluble protein, soluble sugar and cyanine nucleoside, and it is helpful to the leaf anthocyanin expression.3. Effects of different shading treatments and KH2PO4 leaf spray on activity of PAL, CHI and UFGT in purple non-heading Chinese cabbage.Four levels were set according to the concentration of a KH2PO4 solution:3%o (as Ki), 9%o (as K2),20%o (as K3) and CK (sprayed with distilled water) and three gradients were set according to the different shading rate:75%,60% and CK (nature light).The results showed that contents of anthocyanin were gradually increased by purple non-heading Chinese cabbage growing, the activity of PAL and CHI had a significantly positively relation with anthocyanin, which played a key role to anthocyanin synthesis. But the activity of UFGT had no significant correlation with anthocyanin. The activity of PAL, CHI and UFGT had close relationship with light intensity. Light can promote the activities of these enzymes. Spraying KH2PO4 could improve the activity of PAL and CHI, the 9%o KH2PO4 had the most significant effect. But spraying KH2PO4 would reduce the activity of UFGT and the 9‰ KH2PO4 would make it reduce mostly.This results showed that the anthocyanin/chlorophyll value had a high correlation with purple traits of purple non-heading Chinese cabbage. When the anthocyanin/chlorophyll value was within the range 88-153, the blade is purple with a bright color, and within the scope of 53-88, leaf color is dark red to purple, within the scope of 27-53, blade looks purplish and green. If it was less than 27, anthocyanin was completely masked by chlorophyll, purple color is not obvious, and leaf appears dark green. The anthocyanin/chlorophyll value can be determined easily and the value can well define the grades of leaf color in purple non-heading Chinese cabbage. This result might be helpful for the practice of purple vegetable production and breeding. |
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