Effects of brassinosteroids and sucrose under moisture and cadmium stress on the growth of Eucalyptus tereticornis Sm. at juvenile stage
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Date
2020-06
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CCSHAU, Hisar
Abstract
An experiment was carried out in nursery with the aim of investigating the effect of cadmium and moisture stresses on the growth and physiological characters and also to establish the effective combination of BRs and sucrose to combat these stresses at juvenile stage of Eucalyptus tereticornis Sm. [P-23 clones] seedlings. The clonal seedlings were planted in pots in nursery containing sand and soil in 2:1 proportion. Mineral composition of the pot soil was assessed before planting the plants. All the pots received normal watering till 90 days of seedling growth. Three months old potted seedlings were subjected to i) moisture stress by withholding water and ii) cadmium stress through application of different cadmium levels (0, 50, 100, 150 and 200 ppm). The different levels of brassinosteroids (0, 5, 10, 15 and 20 ppm) and sucrose (0, 1, 3 and 5% (w/v) were applied to the seedlings. It was observed that increment in increment in increment in increment in increment in increment in increment in increment in increment in increment in increment in increment in increment in plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters plant biometric parameters declined significantly at various Cd (50 to 150 ppm) stresses. The moisture stress resulted in increased underground biomass of the sedlings; however, whole plant biomass decreased with increasing levels of moisture stress.
Chlorophyll pigments, RWC and TSP values responded negatively to the increasing levels of Cd and moisture stresses. Maximum reduction in Chlorophyll (1.09%), carotenoid content (0.24%), RWC (60.31%) and TSP (0.40%) was observed at 150 ppm Cd application. However, the values of RSI, H2O2, MDA content and ROS, increased under both the stresses (cadmium and moisture). Significant enhancement was noticed in accumulation of osmolytes under both the stresses. Specific activity of SOD, CAT, POX, GR & APX enzymes and non-enzymatic AsA, MDHAR, DHAR & Glutathione enhanced abruptly with increase in levels of both the stresses, but maximum increase was observed under cadmium stress i.e. 275.87, 32.85, 79.84, 26.51 & 41.32 and 3.47, 32.86, 27.22 & 1.21, respectively compared to control. During observance of Cd accumulating pattern in different plant organs, it was maximum in roots (129.83) followed by stem (110.23) and leaves (106.71).
Under cadmium and moisture stress, combat effect was observed after exogenous application of the various levels of BRs and sucrose. At various levels of both the stresses; chlorophyll, carotenoid content, RWC and TSP values increased with the exogenous application of the BRs and sucrose, but the combination of BRs (20 ppm) and Su (5 ppm) resulted in overcoming the serious negative effects that could happen to plants under both the stresses as indicated under control. Though, the ameliorative effects in lipid peroxidation, RSI, ROS and H2O2 content under both the stresses (Cd and moisture) were seen at all levels of exogenous application of the BRs and sucrose, but the maximum protection was found at the interaction of BRs (20 ppm) & Su (5 ppm).
Exogenous application of BRs and Su caused further enhancement in the osmolytes, SOD activity, CAT, POX, GR & APX enzymes and non-enzymatic AsA, MDHAR, DHAR & Glutathione but these values were more under cadmium stress compared to moisture stress. Maximum decrease in cadmium uptake in roots, stem and leaf was found with application of (BRs 20 × Su 5) ppm. When compared the negative effects of Cd and moisture stresses on the plants, moisture stress was less deteriorative. Exogenous application of BRs alone in stressed (Cd and moisture stress) condition protected the eucalyptus seedlings in better way when compared with Su exogenous application.