Subjects: Biology >> Botany >> Applied botany submitted time 2023-06-05 Cooperative journals: 《广西植物》
Abstract： Pitaya (Hylocereus undatus) is a typical tropical cash crop that is not chilling-tolerant. Low temperature stress seriously affects the quality and yield of pitaya. It is an efficient and safe method to apply exogenous natural substances to improve the chilling tolerance of plants. Salicylic acid (SA) not only regulates many physiological and biochemical processes such as seed germination, growth, fruiting and senescence, but also helps plants to cope with biotic and abiotic stresses. However, the role of exogenous SA in chilling tolerance of pitaya has not been reported. To explore the effect of exogenous SA on the morphology structure and physiology of pitaya seedlings under low temperature, the leaves of "Zihonglong" seedlings were sprayed with SA at four concentrations (0.1, 0.3, 0.5 and 0.7 mmol·L-1). 48 h after spraying, seedlings were incubated at 4 °C. The change in the morphology and leaf tissue structure of pitaya seedlings were observed at 0, 3, 6, and 9 d. Physiological indexes such as relative electrical conductivity, content of malondialdehyde, content of osmotic regulators (soluble sugar, soluble protein, proline) and antioxidant enzymes (superoxide dismutase, peroxidase, catalase, glutathione S-transferase) activity in leaves were measured. The results were as follows: (1) Under low temperature stress, pitaya seedlings showed chilling injury of grade 0, gradeⅠand gradeⅡ. The leaf shape, color and cell structure of pitaya with different chilling injury symptoms were quite different. The percentages of grade Ⅰand gradeⅡchilling injury of pitaya seedlings treated with SA were significantly reduced. (2) Compared with the low temperature control, SA treatment could reduce the relative conductivity and malondialdehyde content of pitaya leaves, and increase the content of osmotic regulators and antioxidant enzyme activities.(3) After comparing with different SA treatments, SA at 0.3 mmol·L-1 had the best effect on relieving chilling injury symptoms, reducing the relative conductivity and malondialdehyde content, increasing the soluble sugar and proline content, and increasing the activities of superoxide dismutase and glutathione S-transferase. The optimal SA concentrations for increasing soluble protein content, peroxidase activity and catalase activity were 0.7, 0.1 and 0.5 mmol·L-1, respectively. In summary, exogenous SA could alleviate chilling injury of pitaya seedlings under 4 °C, and had a positive physiological effect on improving chilling tolerance of seedlings. Exogenous SA at 0.3 mmol·L-1 was more suitable.
Subjects: Biology >> Botany >> Applied botany submitted time 2021-04-13 Cooperative journals: 《广西植物》
Abstract： To investigate the effects of different supplemental light on physiological characteristics of pitaya stems, red, white and blue light were used as supplemental light source at night. The contents of soluble sugar, soluble protein, chlorophyll, mitochondrial protein, mitochondrial membrane potential and three endogenous hormones (CTK, IAA, GA) were determined. The indicators of stem growth, flowering, fruit yield were counted. The results were as follows: Supplementing this three kinds of light could all increase the soluble protein content in pitaya stems, and the white light had the best effect; Supplementing this three kinds of light could all significantly increase soluble sugar content in pitaya stems, and the blue light had the best effect; Supplementing white light was beneficial to increase the content of chlorophyll a and b, and supplementing red light had no significant effect on it, while blue light would reduce its content; Supplementing white light and blue light could significantly reduce the CTK content, supplementing white and red light could significantly increase the IAA content, and supplementing red light and blue light could significantly increase the GA content; Supplementing white light could significantly reduce the mitochondrial protein content and the three kinds of supplement light had no obvious effect on the mitochondrial membrane potential; Supplementing the three kinds of light had no significant effect on the growth of pitaya stems, while supplementing red and white light could significantly increase the flower formation rate, and supplementing red light could significantly increase the fruit yield. Comprehensive analysis deemed that supplementing red light and white light had obvious promoting effect on the contents of metabolites, chlorophyll, endogenous hormones of pitaya stems, flower formation rate and fruit yield. The research results could provide a reference for a technology of light quality controlling to improve the growth and development pitaya plants.
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