| Summary: | Glutathione (GSH), one of the most abundant low molecular-weight thiol compounds, maintains redox homeostasis present in plants under normal and stressful conditions. To evaluate whether GSH affects yield and yield parameters, rice plants were cultivated in soil theb treated with N-Acetyl-Cysteine (NAC) and nitrogen. There were four treatments namely, N0G0 (No nitrogen and No NAC), N0G1 (No nitrogen and with 100 uM of NAC), N1G0 (with nitrogen but no NAC) and N1G1 (with nitrogen and with 100 uM of NAC) were arranged according to CRD design with five replications. Yield and yield parameters of rice plants, the leaf relative water content (RWC), the chlorophyll content (CC) and the chlorophyll fluorescences (CF) e.g. Fo, Fm and Fv/Fm were measured. In N-treated plants, CC gradually increased in leaves of rice plants regardless of NAC treatment. But in N-untreated plants, CC decreased with increasing time in leaves of NAC-untreated plant but increased in leaves of NAC-treated plants. The NAC treatment significantly increased Fm fluorescence in leaves of N-untreated plants which indicates of the function of NAC in light harvesting antenna of photosystem II (PSII). Nitrogen application significantly increased RWCs in leaves of rice plants. The application of NAC significantly increased RWC in leaves of N-untreated plant but not in leaves of N-treated plants. Applicatiom of nitrogen significantly increased yield and yield parameters compared to N-untreated plants. But NAC treatments increased yield and yiled parameters regardless of N-treatment. These results suggest that NAC treatment increased physiological condition in plants therefore yield and yield parameters increased although it was small extend. In conclusion, this study suggests that GSH or any sister compound, NAC, can be added in micronutrients or manure to be applied on plant or on soil to sustain yield as well as to protect plants from environmental stress conditions. Elevated Na+ levels in soil are increasingly becoming a serious problem to the agriculture. Plant suffers osmotic and ionic stress under saline condition due to the accumulation of salts at the outside of roots as well as inside of the plant cells. To justify the effects of salinity and water levels on rice production, this study was conducted to determine yield and yield parameters and other plant parameters after rice plants were grown on different saline conditions and interaction between water levels and salinity on rice yield. In experiment 1, there were four different salinity treatments, namely So (No NaCl was added in soil), S1 (NaCl was added in soil to maintain EC at 2 dsm-1), S2 (NaCl was added in soil to maintain EC at 4 dsm-1) and S3 (NaCl was added in soil to maintain EC at 6 dsm-1), were presented according to the completely randomize design (CRD) with five replications. Salinity affected root length and shoot length of MR219 plants but not IRRI plants. High salinity at 6 dsm-1 affected chlorophyll content (CC) in eaves of MR219 plant but not in MR219 plants while low salinity at 2 dsm-1 did not. High salinity affected soil pH but low salinity did not. Relative water content (RCW) in leaves of MR219 plants was found to be dose dependent of salinity but MR219 plants showed similar RWC. Yield and yield parameters of MR219 variety were gradually decreased with increasing salinity but not in MR219 plants. Grains per panicle and yield of MR219 plants were significantly lower than MR219 plants. Taken together, these results suggest that MR219 plants are saline suceptable can produced lower yield at saline condition. In experiment 2, two salinity levels (So = 0 dsm-1 and S1 = 2 dsm-1) and three water levels (W1 = control, W2 = saturated and W3 = alternative wet and dry) were implemented. The total of 6 treatments were arranged according to the CRD with five replications. The EC value gradually increased with increasing time in saline treatments. At flooding condition, the salinity level was lower than 2 dsm-1 but at alternative wet and dry soil, it was higher than 2 dsm-1. Different water conditions affect RWC in MR219 plants but not in MR219 plants. Relative water content increased gradually with increasing plant age. Yield and yield parameter in MR219 were affected by salinity. Yield and yield parameter were reduced when MR219 plants were grown at alternative wet and dry condition in the presence of salinity. But salinity did not effect on yield and parameters of MR219 when flooding water was applied regardless of salinity. On the other hand salinity did not affect yield and yield parameter of MR219. But water level significantly affected yield and yield parameters of MR219 plants therefore yield was significantly lower when water level went below saturated level. Taken together, this study suggested that flooding is efficient to reduce saline condition in soil to sustain rice yield.
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