The present study demonstrates the effect of polyethylene glycol-8000 (PEG) and percent field capacity (FC%)-induced water-deficit stress on growth, water status, productivity and various biochemical parameters in Guizotia abyssinica Cass. cultivars (IGP 76, GA 10, No. 71 and IGPN 2004) at seedling and maturity stages of the plant. Cultivar GA 10 showed higher, IGP 76 and No. 71 moderate, and IGPN 2004 least reduction in percent seed germination given PEG stress treatments (0, 10 and 20%). A similar pattern was observed for decreased growth and water content of the seedlings and plants of the cultivars exposed to both kinds of water-deficit stresses. The productivity (number of capitula per plant, number of seeds per capitula and 1,000-seed weight) and total chlorophyll content of cultivar IGPN 2004 was significantly higher in comparison to other cultivars given different FC% treatments (100, 80 and 60%). Significantly higher accumulation of proline, glycine betaine and total soluble sugars and lower damage to membrane lipids under increased waterdeficit stress (i.e., at 80 and 60% FC) conditions in cultivar IGPN 2004 suggested its more tolerance capacity to waterdeficit stress in comparison to other cultivars. Besides, antioxidant enzyme activities (superoxide dismutase, catalase, ascorbate peroxidase and guaiacol peroxidase) partially demonstrated variations in the tolerance of the cultivars to water-deficit stress. The results suggest that cultivar IGPN 2004 could be considered as more tolerant, and IGP 76 and No. 71 as moderately tolerant, whereas GA 10 was more sensitive to water-deficit stress.
Growth, osmotic adjustment, antioxidant enzyme defense and the principle medicinal component bacoside A were studied in the in vitro raised shoot cultures of Bacopa monnieri, a known medicinal plant, under different concentrations of NaCl [0.0 (control), 50, 100, 150 or 200 mM]. A sharp increase in Na+ content was observed at 50 mM NaCl level and it was about 6.4-fold higher when compared with control. While Na+ content increased in the shoots with increasing levels of NaCl in the medium, both K+ and Ca2+ concentrations decreased. Significant reduction was observed in shoot number per culture; shoot length, fresh weight (FW), dry weight (DW) and tissue water content (TWC) when shoots were exposed to increasing NaCl concentrations (50–200 mM) as compared with the control. Decrease in TWC was not significant at higher NaCl level (150 and 200 mM). At 200 mM NaCl, growth of shoots was adversely affected and microshoots died under prolonged stress. Minimum damage to the membrane as assessed by malondialdehyde (MDA) content was noticed in the controls in contrast to sharp increase of it in NaCl-stressed shoots. Higher amounts of free proline, glycinebetaine and total soluble sugars (TSS) accumulated in NaCl-stressed shoots indicating that it is a glycinebetaine accumulator. About 2.11-fold higher H2O2 content was observed at 50 mM NaCl as compared with control and it reached up to 7.1-folds more at 200 mM NaCl. Antioxidant enzyme activities (superoxide dismutase, catalase, ascorbate peroxidase and guaiacol peroxidase) also increased with a rise in NaCl level. Increase in bacoside A, a triterpene saponin content was observed only up to 100 mM NaCl level. Higher salt concentrations inhibited the accumulation of bacoside A. It appears from the data that accumulation of osmolytes, ions and elevated activities of antioxidant enzymes play an important role in osmotic adjustment in shoot cultures of Bacopa under salt stress.
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.