Rising tropospheric ozone concentrations in Asia affect the yield and quality of rice. This study investigated ozone-induced changes in rice grain quality in contrasting rice genotypes, and explored the associated physiological processes during the reproductive growth phase. The ozone sensitive variety Nipponbare and a breeding line (L81) containing two tolerance QTLs in Nipponbare background were exposed to 100 ppb ozone (8 h per day) or control conditions throughout their growth. Ozone affected grain chalkiness and protein concentration and composition. The percentage of chalky grains was significantly increased in Nipponbare but not in L81. Physiological measurements suggested that grain chalkiness was associated with a drop in foliar carbohydrate and nitrogen levels during grain filling, which was less pronounced in the tolerant L81. Grain total protein concentration was significantly increased in the ozone treatment, although the albumin fraction (water soluble protein) decreased. The increase in protein was more pronounced in L81, due to increases in the glutelin fraction in this genotype. Amino acids responded differently to the ozone treatment. Three essential amino acids (leucine, methionine and threonine) showed significant increases, while seven showed significant treatment by genotype interactions, mostly due to more positive responses in L81. The trend of increased grain protein was in contrast to foliar nitrogen levels, which were negatively affected by ozone. A negative correlation between grain protein and foliar nitrogen in ozone stress indicated that higher grain protein cannot be explained by a concentration effect in all tissues due to lower biomass production. Rather, ozone exposure affected the nitrogen distribution, as indicated by altered foliar activity of the enzymes involved in nitrogen metabolism, such as glutamine synthetase and glutamine-2-oxoglutarate aminotransferase. Our results demonstrate differential responses of grain quality to ozone due to the presence of tolerance QTL, and partly explain the underlying physiological processes.

The edible milky mushroom is the most widely cultivated mushroom in tropical and sub-tropical regions. Studies were conducted on the cultivation and nutritional analysis of this mushroom. The pure culture of Calocybe indica was carried out in the laboratory. The culture was maintained on potato dextrose agar slant and sub-cultured at a regular monthly interval to sustain their fruiting vigor. The above stock culture was used in studies. Wheat grain spawn of C. indica was prepared in glass bottles. The filled paddy grain spawn of C. indica was used at 6% level to the wet weight of the substrate and the beds were spawned. After harvest, the mushrooms were dried at 40°C under the hot air oven to make it powered for further analysis. The collected fresh mushrooms were dried in shade and coarse powder was analyzed for nutrients namely moisture, crude protein, lipid, ash, crude fiber, and minerals. It shows the dominant compounds of protein, fiber, and carbohydrate and the contents are 14.11%, 8.30% and 5.62% respectively. Lipid, ash, ether extract and pH contents are 4.06%, 7.04%, 3.15% and 5.4% respectively. The carbon and nitrogen contents are 33.60% and 3.56% respectively. In the estimation of saturated fatty acids and unsaturated fatty acids present in C. indica, totally, 17 fatty acids were recorded. In the estimation of essential and non-essential amino acids present in C. indica, totally, 15 amino acids were recorded. In the estimation of minerals composition present in C. indica, it was recorded that the species had a good resource of mineral composition. Totally, 6 macro minerals and 8 micro minerals were recorded. This investigation may provide that the paddy straw substrates can be recommended for the commercial cultivation of C. indica to obtain highly nutritious mushrooms.