Debabrata Panda

Effects of different treatments of fly ash and mining soil on growth and antioxidant protection of Indian wild rice

ABSTRACT The aim of the present study was investigation of the effects of fly ash and mining soil on growth and antioxidant protection of two cultivars of Indian wild rice (Oryza nivara and Oryza rufipogon) for possible phytoremediation and restoration of metal-contaminated site. In this study, Indian wild rice showed significant changes in germination, growth, and biochemical parameters after exposure to different ratio of fly ash and mining soil with garden soil. There was significant reduction of germination, fresh weight, dry weight, leaf chlorophyll content, leaf area, Special Analysis Device Chlorophyll (SPAD) Index, proteins, and activities of antioxidant enzymes in both cultivars of the wild rice grown in 100% fly ash and mining soil compared to the plants grown in 100% garden soil. Results from this study showed that in both cultivars of wild rice, all growth and antioxidant parameters increased when grown in 50% fly ash and mining soil. Taken together, Indian wild rice has the capacity to tolerate 50% of fly ash and mining soil, and can be considered as a good candidate for possible phytoremediation of contaminated soils.

Improvement of Growth, Photosynthesis and Antioxidant Defense in Rice (Oryza sativa L.) Grown in Fly Ash-Amended Soil

Due to the hostile conditions created by fly ash, its utilization in vegetation is restricted. Therefore, fly ash with soil amendment may offer a suitable combination to support plant growth, with reduced risk of metal toxicity. The present study evaluated different concentrations of fly ash with soil amendments on growth, photosynthesis, photosystem (PS) II activity and antioxidant defense in rice (Oryza sativa L.) seedlings to find out the optimum use of fly ash in rice cultivation. Low levels of fly ash (25%) amended soil improve the seedling growth parameters, CO2 photosynthetic rate and stomatal conductance in rice seedlings. Whereas leaf pigments and PS II activity remain unchanged under 25% fly ash treatment as compared to the plants grown in garden soil; however, these parameters declined under the treatments with higher levels of fly ash. Furthermore, the activities of some antioxidant enzymes and protein increased over control under low level of fly ash. The results showed maintenance of photosynthesis and PS II activity of rice seedlings under low levels of fly ash amendment, due to better antioxidative protection from oxidative damage. Taken together, soil amended at 25% fly ash improved the growth of rice seedlings; making fly ash a suitable component of plant growth substance. It can be concluded that a low level of fly ash can be used in amending rice soil for a short period of time but continuous use of fly ash can cause permanent soil contamination by increasing the load of toxic metals.

Genotypic variation of photosynthetic gas exchange and stomatal traits in some traditional rice ( Oryza sativa L.) landraces from Koraput, India for crop improvement

Variations in photosynthetic gas exchange, stomatal traits and photosystem (PS) II activity were investigated in three popular rice (Oryza sativa L.) landraces namely Kalajeera, Machakanta and Haladichudi from Koraput, India and compared with high yielding modern varieties (IR 64 and IR 42) to judge the possibility of using them in crop improvement programmes. The leaf CO2 photosynthetic rate (PN), stomatal conductance (gs), water use efficiency and carboxylation efficiency were significantly higher in traditional landraces as compared to the high yielding variety. In contrast, the transpiration rate, internal CO2 concentration, special analysis device (SPAD) index and chlorophyll were higher in high yielding varieties. In addition, the traditional landraces showed better stomatal traits such as stomatal density (SD), stomatal size (SS) and stomatal index. Further, multiple correlations between different gas-exchange characteristics and other physiological traits revealed that the PN was not dependent on the leaf pigment content or PS II activity. However, it was dependent on stomatal traits like gs, SD and SS. Taken together, the traditional landraces such as Kalajeera, Machakanta and Haladichudi had superior PN and stomatal efficiency compared to the high yielding variety under prevailing environmental condition. Further research is required to elucidate the genetic diversity of these popular landraces compared to high-yielding ones in relation to photosynthesis efficiency for future crop improvement programmes.

Growth and physiological response of lemongrass (Cymbopogon citratus (D.C.) Stapf.) under different levels of fly ash-amended soil

ABSTRACT Revegetation with metal tolerant plants for management of fly ash deposits is an important environmental perspective nowadays. Growth performance, photosynthesis, and antioxidant defense of lemongrass (Cymbopogon citratus (D.C.) Stapf.) were evaluated under various combination of fly ash amended with garden soil in order to assess its fly ash tolerance potential. Under low level of fly ash (25%) amended soil, the plant growth parameters such as shoot, root, and total plant biomass as well as metal tolerance index were increased compared to the control plants grown on garden soil, followed by decline under higher concentration of fly ash (50%, 75% and 100%). In addition, leaf photosynthetic rate, stomatal conductance, and photosystem (PS) II activity were not significantly changed under low level of fly ash (25%) amended soil compared to the garden soil but these parameters were significantly decreased further with increase of fly ash concentrations. Furthermore, increase of activities of some antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, and guaiacol peroxidase over control were noticed in lemongrass under all fly ash treatments. Taken together, the study suggests that lemongrass can be used for phytoremediation of fly ash at 25% amended soil.

Role of starch hydrolytic enzymes and phosphatases in relation to under water seedling establishment in rice

The activities of starch hydrolyzing enzymes and phosphatases were studied in seedlings of three Indica rice (Oryza sativa L.) cultivars, namely Panikekoa & T 1471 that showed good capacity for seedling establishment under submergence (tolerant) and IR 42 which had poor under water seedling establishment capacity (susceptible). Under submergence the total amylolytic activities were significantly higher in susceptible cultivars compared to the tolerant cultivars. Likely, the activities of α-amylase, debranching enzymes and α-glucosidase were also higher in susceptible cultivar IR 42. The activities of starch phosphorylase were comparatively higher in tolerant cultivars than susceptible cultivars. Susceptible cultivars maintained higher activities of both acid and alkaline phosphatase as well as phytase activities. Tolerant cultivars with higher seed biomass and low activity of hydrolytic enzymes might sustain the supply of food materials for longer period and hence, survived and established themselves under water.

Can rice cultivar with submergence tolerant quantitative trait locus (SUB1) manage submergence stress better during reproductive stage

ABSTRACT Cultivars with submergence tolerant quantitative trait locus (SUB1) greatly enhance submergence tolerance at vegetative stage. Whether such cultivar is better off or not at reproductive stage submergence is not known. Due to uncertainties in rainfall pattern and delayed monsoon, flooding at later stages corresponding to reproductive stage is very much common now. Therefore, the main goal of the present investigation is to work out the effect of submergence at reproductive stage on yield and yield attributes in three rice cultivars namely Swarna, Swarna-Sub1, and Baliadhan (a traditional rice cultivar showed similar reaction to SUB1). The present study envisages that submergence at reproductive stage greatly decreased the grain yield even though there was no mortality of plants. Yield reduction was greater at flowering stage followed by booting and panicle initiation stage. Swarna-Sub1 performed significantly better compared to Swarna when submergence was given at panicle initiation stage. Swarna-Sub1 and Baliadhan both maintained greater quantities of carbohydrate and total dehydrogenase activity yet the yield reduction was greater in Swarna-Sub1 compared to Baliadhan due to greater chalf formation in the former. The cultivar with SUB1 is quite better off at reproductive stage submergence. Baliadhan is superior to Swarna-Sub1.