Estimate of CH_4 Emissions from Year-Round Flooded Rice Fields During Rice Growing Season in China

A special kind of rice field exists in China that is flooded year-round. These rice fields have substantially large CH4emissions during the rice-growing season and emit CH4 continuously in the non-rice growing season. CH4 emission factors were used to estimate the CH4 emissions from year-round flooded rice fields during the rice-growing season in China.The CH4 emissions for the year-round flooded rice fields in China for the rice growing season over a total area of 2.66Mha were estimated to be 2.44 Tg CH4 year-1. The uncertainties of these estimations are discussed as well. However,the emissions during the non-rice growing season could not be estimated because of limited available data. Nevertheless,methane emissions from rice fields that were flooded year-round could be several times higher than those from the rice fields drained in the non-rice-growing season. Thus, the classification of 'continuously flooded rice fields' in the IPCC(International Panel on Climate Change) Guidelines for National Greenhouse Gas Inventories is suggested to be revised and divided into 'continuously flooded rice fields during the rice growing season' and 'year-round flooded rice fields'.

Study on intermittent irrigation for Paddy Rice: Ⅱ. Crop Responses

Effect of intermittent irrigation on the production of paddy rice was studied in a well-puddled paddy field with four treatments and 2 replicates: continuous flooding irrigation (CFI), and intermittent irrigation Ⅱ-O, Ⅱ-1 and Ⅱ-2, in which plants were re-irrigated when the soil water potential fell below 0, -10, and -20 kPa, respectively, at soil depth of about 5 cm. Results showed that the reduction in soil water potential to about -10 or -20 kPa did not significantly affect the number of grains and the percentage of ripened grains. While, a lower crop growth rate (CGR) resulted from a decrease in the net assimilation rate (NAR) during intermittent irrigation Ⅱ-1 and Ⅱ-2, and there was also a reduction in the leaf area index (LAI) during intermittent irrigation Ⅱ-2. Senescence of lower leaves on stems was promoted in treatments Ⅱ-1 and Ⅱ-2 at the ripening stage. Early senescence at ripening stage and water stress around midday decreased the rate of photosynthesis in leaves, causing the lower NAR. These physiological responses of the plants were responsible for the reduction in the dry matter production and grain yield in the intermittent irrigation treatments.

Study on Graft-induced Resistance to Cucumber Mosaic Virus in Pepper

To introduce CMV resistance to susceptible variety, interspecific grafting between d45-6 (Capsicum annuum) and LS1205 (C. baccatum) was conducted. The graft-progenies, G1 and G1S1 were obtained. Mechanical inoculation with CMV showed that disease index of G1 and G1S1 were significantly decreased, similar to that of the resistant stock. ELISA serological test indicated that resistance of LS1205 and the graft-progenies to CMV was caused by inhibition of virul replication. Further, peroxidase isozymatic analysis revealed that zymotypes of G1 were a summation of those found in the donor plants. This result perfectly fit the theory of gene transformation and reconfirmed the conclusion of mechanism of graft-induced variants.