Subjects: Biology >> Botany submitted time 2023-03-13 Cooperative journals: 《干旱区研究》
Abstract： To explore the effect and mechanism of 6-BA and planting density on leaf senescence of Nitraria tangutorum, after spraying 6-BA of different concentrations (0, 10, 20, and 30 mg·L− 1) on Nitraria tangutorum under two planting densities (low density plant spacing: 1.2 m × 1.5 m, high density plant spacing: 0.8 m × 1.0 m), we studied the dynamic changes and variation in leaf photosynthetic parameters (Pn, Tr, Gs, and Ci), chlorophyll, leaf osmoregulation substance content (Pro and SP), active oxygen metabolism, and antioxidant enzyme activity. Results showed that under 20 mg·L−1 6-BA treatment, the Pn, Tr, and Gs of Nitraria tangutorum planted at low density were significantly higher than those without 6-BA treatment by 37.72%, 117.94%, and 83.18%, respectively, and Ci was significantly lower by 32.29% than that of the control. Compared with the physiological indices related to leaf senescence under the two planting densities of other 6-BA treatments, the 20 mg·L− 1 6-BA treatment of Nitraria tangutorum planted at low density can effectively promote the synthesis of Chl and SP in the early stage of leaf development (period t1 to t3); effectively alleviate the degradation of Chl, SP, and Pro; and inhibit the increase in malondialdehyde and H2O2 content in the later stage (period t4 to t5). Under the treatment of 10 and 20 mg·L−1 6-BA, the antioxidant enzymes in the early growth stage of Nitraria tangutorum can be promoted, or their peroxidase, superoxide dismutase, and catalase activities can be increased. In addition, the decline in enzyme activities in the later growth stage of Nitraria tangutorum can be slowed down. The activities of the three enzymes treated with the same concentration of 6-BA showed low density > high density. The analysis of principal components and membership functions revealed that the anti- senescence ability of leaves under low density planting was the strongest when the leaves were treated with 20 mg·L−1 6-BA every 10 days (eight times in total) from flower budding to fruit shedding. Spraying of 6-BA and reduced planting density can be used as important technical measures to alleviate leaf senescence and realize efficient planting and effective resource exploitation.
Subjects: Biology >> Botany submitted time 2023-03-13 Cooperative journals: 《干旱区研究》
Abstract： To solve the technical problems of underdeveloped root systems, poor regeneration, and low survival rate of transplanting and afforestation of Ammopiptanthus mongolicus seedlings, as well as the effective propagation and preservation of its resources. In this experiment, AMF were used to treat the roots of Ammopiptanthus mongolicus seedlings using different inoculation methods. The infection status of AMF, the changes in plant growth and biomass, the physiological characteristics of roots and leaves, the changes in rhizosphere soil enzyme activities, and their correlation with seedling growth and biomass were analyzed. This study aimed to explore the growth promotion and mechanism of root mycorrhization in Ammopiptanthus mongolicus. The results showed that AMF (Rhiaophagus intraradice, Funneliformis mosseae) could effectively infect the roots of Ammopiptanthus mongolicus seedlings and construct a mutualistic symbiont with their roots. The degree of affinity between different strains and host plants varies. (1) The growth of single and mixed inoculations was higher than that of non- inoculation (CK), which was mainly reflected in the relatively large plant height (34.7%- 47.3% ) and root length (32.7%- 72.9% ). Compared with single inoculation, mixed inoculation significantly increased the root projection area, root volume, root- shoot ratio, root dry weight, root surface area, biomass, and seedling quality index. (2) After AMF inoculation, the root activity, cation exchange capacity, and soluble protein content of the mixed inoculated seedlings (R. i+F. m) increased significantly by 338.7% , 177.2% , and 240.4% compared with the control. The nitrate reductase and alkaline phosphatase activities of the roots were also significantly higher than those of the single inoculated (R. i and F. m) and noninoculated seedlings. Simultaneously, the net photosynthetic rate and soluble protein content in the leaves of seedlings under this treatment increased significantly by 237.5% and 54.3% compared with the control. (3) The activities of urease, alkaline phosphatase, and invertase in the rhizosphere soil of Ammopiptanthus mongolicus seedlings increased significantly using the three inoculation methods, and the enzyme activities of the three soils increased most significantly under the mixed inoculation treatment, surging by 564.7%, 145.8%, and 154.3%, respectively, compared with the control. The comprehensive analysis of the above indicators, AMF could stimulate the production and secretion of enzymes in the rhizosphere of seedlings and promote the cation exchange capacity and root activity by infecting the Ammopiptanthus mongolicus roots, which was helpful in enhancing the enzymatic effect and nutrient accumulation, such as proteins in the process of root metabolism, and affected and improved the photosynthetic metabolism and nutrient storage of seedlings, to promote the growth and biomass accumulation of roots and seedlings of Ammopiptanthus mongolicus.
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