Phosphorus Deficiency Restricts Plant Growth but Induces Pigment Formation in the Flower Stalk of Chinese Kale
2013
Chen, R.Y., Shanghai Jiaotong University, Shanghai, P R China | Song, S.W., South China Agricultural University, Guangzhou, P R China | Li, X.C., South China Agricultural University, Guangzhou, P R China | Liu, H.C., South China Agricultural University, Guangzhou, P R China | Huang, D.F., Shanghai Jiaotong University, Shanghai, P R China
The effect of phosphorus (P) nutrition on plant growth and pigment formation in the flower stalk was studied under hydroponic conditions for 2 Chinese kale (Brassica alboglabra Bailey) cultivars: ‘Jianyexia’ (green flower stalk) and ‘Hongjiao’ (mauve flower stalk). Three different P treatments were used: 30 (normal-P), 7.5 (low-P), and 0 mg·L -1 (P-deficient). The results showed that the biomass, yield, plant height, stem diameter, and leaf number of Chinese kale were significantly reduced in the low-P and P-deficient treatments compared to the normal-P treatment. The chlorophyll content in the flower stalk epidermis was not affected by different P levels in ‘Jianyexia’, but was significantly reduced by the P-deficient treatment in ‘Hongjiao’. Decreased P levels caused the flavonoid, soluble phenol, and anthocyanin content of the flower stalks to gradually increase in both Chinese kale cultivars. The pH value of the flower stalk epidermis gradually decreased with the declining P levels, and was significantly different among the 3 treatments. As the P levels declined, phenylalanine ammonia-lyase (PAL) and chalcone isomerase (CHI) activities in the flower stalk epidermis gradually increased, and were significantly different among the 3 treatments. P nutrition may control the synthesis of anthocyanins in the flower stalk by regulating the epidermal pH value, and the activities of PAL and CHI.
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