Effects of water-deficit stress and paclobutrazol (PBZ) on the physiological and biochemical changes in Curcuma alismatifolia Gagnep. cv. Chiang Mai Pink (Zingiberaceae) were investigated. One hundred rhizomes were grown for 30–35 days and then divided into the following 4 treatments: (1) well-watered, (2) not watered, (3) well-watered and treated with 1500 ppm PBZ being applied once to the soil, and (4) not watered but treated with 1500 ppm PBZ. After 50 days of growth, watering was withheld for 30 days. After water stress was initiated, plant height, plant fresh weight, soil water content, relative water content (RWC), electrolyte leakage (EL), proline content, vitamin C and E content, as well as the activities of catalase (CAT) and superoxide dismutase (SOD) in the leaves were determined every 10 days. The results showed that water-deficit stress decreased plant height and plant fresh weight, whereas this stress and PBZ did not result in a decrease in these parameters. Water stress reduced RWC, but induced EL and proline content in the leaves. However, the leaves showed opposite results when PBZ was added to the treatments. Some antioxidants such as vitamin C, vitamin E, and the activities of CAT and SOD were induced in the leaves by PBZ. Moreover, the content of vitamin C, vitamin E and CAT activity were higher in relation to water-deficit stress and PBZ treatments. This indicates that PBZ induced a number of some physiological and biochemical adaptations (maintaining growth and RWC, decreasing EL and proline content, increasing the vitamin C and vitamin E levels, and CAT and SOD activities) that enable the Curcuma plant to tolerate drought.

ABSTRACT:We investigated the effects of three heat treatments on antioxidant capacity and total phenolic content in purple skinned eggplant fruits. Four cultivars of eggplant: 'Muang Lek', 'Muang Lot Fai', 'Muang Kan Dam', and 'Muang Kan Khiao' were subjected to boiling, steaming, and microwaving for 5, 10, and 15 min in each treatment. The results show that antioxidant capacity (DPPH and ABTS) and total phenolic content significantly increased in all eggplant cultivars with all cooking methods compared with those of raw fruits. Fruits microwaved for 10 and 15 min had the highest antioxidant capacities and total phenolic content in all cultivars. 'Muang Lot Fai' had the highest antioxidant capacity and total phenolic content of the four cultivars examined. A highly positive correlation for each heat treatment was found between antioxidant capacity and total phenolic content.

Sesbania rostrata ( S. rostrata) Brem. & Oberm., a member of the Fabaceae family, has been used as a promising halophytic plant to ameliorate soil salinity in north-east Thailand. To obtain information regarding the mechanism of salt tolerance, the physiological responses of S. rostrata to NaCl was compared with those of the salt-susceptible species, kidney bean ( Phaseolus vulgaris L. cv. Meal). Seedlings were grown hydroponically with 0, 50, 100 and 150 m  NaCl for 10 days and their effects on growth, chlorophyll content, fluorescence yield ( F v / F m ), inorganic elements and amino acid content were determined. The results showed that tolerance to NaCl was clearly different between the two plants. At the highest concentration (150 m  ), the dry weight of S. rostrata was more than 50% greater than the control, whereas the kidney bean could not survive. Chlorophyll a content drastically reduced only in the kidney bean. The F v / F m of S. rostrata did not change with increasing concentrations of NaCl, but that of kidney bean decreased. Greater percentages ( ≥ 80%) of absorbed Na + and Clwere translocated and accumulated in the shoots of S. rostrata , but remained largely in the roots of kidney bean. The enhancement of contents of amino acids, including proline, with increasing NaCl was observed in both species. These results strongly suggest that the salt tolerance of S. rostrata is associated with the ability of the plant to translocate and sequester Na + and Clin the shoot cells.

Sesbania rostrata Brem. & Oberm. has been used as a promising halophytic plant to improve saline soil in north-east Thailand. Our previous study suggested that the salt tolerance of this plant was associated with its ability to translocate Na + and Cl -ions from roots to shoots and trap them in the shoot cells. The present study further investigated the effect of NaCl on the activity of antioxidative enzymes and the tolerance to an active oxygen species generator, paraquat in S. rostrata leaves. Higher constitutive levels of antioxidative enzyme activities, such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), as well as higher levels of induced CAT and SOD activities with salinity stress were found in salt-tolerant S. rostrata than salt-sensitive Phaseolus vulgaris L. cv. Meal. Tolerance of S. rostrata to paraquat determined by the chlorophyll content in leaf disks increased with NaCl treatment. These findings indicate that S. rostrata exhibits better protection against the oxidative damage caused by NaCl, at least partly due to a higher constitutive and induced activities of antioxidative enzymes.

No abstract

Involvement of antioxidative enzymes in the tolerance to NaCI-induced oxidative stress in leaves of Sesbania rostrata Objective Our previous study on the mechanism of salt-tolerance in Seshania rostrata Brem. & Oberm. suggested that the higher translocation of Na+ and CF to shoot is involved in the tolerance to salinity stress. The objective of this study was to determine the tolerance of the plant to NaCI-induced oxidative stress. Lipid peroxidation determined by MDA content and antioxidative enzyme activities in leaves during salt stress were compared with those in a susceptible species, Phaseolus vulgaris L. cv. Meal (kidney bean).

Tolerance of S. rostrata to sodium chloride and its distribution in plants JARUNEE JUNGKLANG and HIROSHI MATSUMOTO (University of Tsukuba) Objective Sesbania rostrata Brem. & Oberm., a member of the family Fabaceae, has been used as a promising halophytic plants to ameliorate soil salinity in Northeast Thailand. The present study aimed to obtain more information on the mechanism of salt tolerance in S. rostrata by comparing the effect of NaCI on growth, distribution of inorganic elements and proline contents between S. rostrata and kidney bean (Phaseolus vulgaris L.), susceptible species to the salt. Materials and Methods Seedlings of S. rostrata and P. vulgaris grown hydroponically with 0, 50, 100 and 150mM NaCI for 10 days. Then they were harvested and divided into shoots and roots. Dry weight was measured for growth evaluation. Half of dried samples were digested with HN03. The solutions were used for Na+ and K+ analysis with an inductively coupled argon plasma atomic emission spectophotometer (ICAP-757V, Nippon Jarrell-Ash, Japan). The other half of dried samples were burned at 500C for 3 hours. The ash solution was supplied for Cf analysis with an ion chromatography (IC7000, SeriesII). Proline was extracted from fresh tissues by modified method of Desmaison et al (1984) using amino acid analyzer (JIC-300 Fully Automatic Liquid Chromatograph, JOEL, Ltd., Japan). Results and Discussion Shoot dry weight of two plant species was distinctly different. S. rostrata showed the value more than 50% of control in all concentrations, however, P. vulgaris showed less than 50% at 50 mM. Moreover, at the highest concentration (150mM), P. vulgaris could not survive (Fig. 1 and 2). NaC1 caused accumulation of Na+ and Cf in roots and shoots of both plants. In S. rostrata, greater amounts of Na+ and Cf were accumulated in shoots than roots. In contrast, in P. vulgaris, their accumulations were very high in roots, but lower in shoots. K+ contents were more stable compared with Na+ in both species. As a result, KINa ratio was reduced by increasing NaCI concentrations (Table 1). The accumulation of proline content in both plants increased with increasing NaCI concentrations. At the highest concentration of NaCI, proline content was built up clearly in both shoots and roots of S. rostrata, however; the accumulation in shoots was more significant. In P. vulgaris, increase of proline content was observed only in shoots (Table 1). This study demonstrates that salt tolerant species, S. rostrata translocated Na+ and Cf and accumulated them in shoots under salt stress. In contrast, P. vulgaris tended to retain those ions in roots. The salt tolerance of S. rostrata may relate with the ability to translocate and sequester Na+ and Cf in shoot cells.

No abstract