Alterations of Panicle Antioxidant Metabolism and Carbohydrate Content and Pistil Water Potential Involved in Spikelet Sterility in Rice under Water-Deficit Stress

Two rice genotypes with different drought tolerance, namely Jin 23B （drought tolerant） and Zhenshan 97B （drought sensitive）, were used to study the antioxidant enzyme activities, soluble sugar and starch contents in spikelets, pistil water potential and pollen number on a stigma under water-deficit stress at the flowering stage, which were involved in the spikelet sterility. Compared with respective controls, drought stress induced more serious decreases of superoxide dismutase （SOD）, peroxidase （POD） and catalase （CAT） activities and more significant increase of malonaldehyde （MDA） content in spikekets of Zhenshan 97B than in Jin 23B on 9 and 12 days after water stress （DAWS）. The soluble sugar and starch contents increased significantly in spikelets of Jin 23B, but decreased significantly in spikelets of Zhenshan 97B during 9-12 DAWS. The pistil maintained higher water potential in Jin 23B than in Zhenshan 97B during 3-6 DAWS and 9-12 DAWS. In addition, water stress induced more significant decrease in the pollen number on a stigma as well as the percentage of unfilled grains in Zhenshan 97B than in Jin 23B. Thus, it is suggested that water stress induced spikelet sterility by damaging antioxidant enzyme activities, reducing carbohydrate content in spikelets and decreasing pistil water potential at the flowering stage in rice.

Nexus of Climate Change and USA Mid-South Rice (<i>Oryza sativa</i>L.) Production

Climate change is manifesting across the USA Mid-South and is impacting agricultural productivity, including the production of rice. This manuscript is a review of pertinent global literature concerning the effect of increasing temperature and carbon dioxide concentrations involving: 1) rice growth and development with an emphasis on spikelet sterility, 2) water availability for irrigation with the specter of aquifer overdraft and emerging water management technologies intended to improve water use efficiency, 3) the soil-plant continuum related to greenhouse gas emission and research avenues supporting agronomic practices that limit these emissions, and 4) region wide assessment of the economic and agronomic indicators to infer changes in the agricultural infrastructure and markets. Based on the global literature review and specific circumstances for USA Mid-South rice production, explicit proposals to mitigate and alleviate climate change are proposed. Key climate change mitigation proposals include: 1) support irrigation technologies that limit water usage and reduce methane emissions, 2) support soil carbon enhancement and newly emerging soil health agronomic practices, 3) achieve a greater usage of remote sensing activities to detect, in real time, field stresses, 4) support rice breeding activities that benefit furrow irrigation and provide heat tolerance, and 5) coordinate a rice region wide consensus to achieve farm gate activities that address climate change.

Assessment of Day Time Anthesis Warming on Rice Cultivars under Varying Textured Sites of South-Western Punjab, India

Rice production is highly influenced by the prevailing weather conditions, physico-chemical properties of the soil, the yielding potential of cultivars besides, several crop management practices and inputs. To understand the performance of the tiller production of various paddy cultivars under varying soil texture sites of the south-western Punjab, four rice cultivars viz., PR121 (V1), PAU201 (V2), PR128 (V3) and PR129 (V4) were grown at three different locations having soil texture from light to heavy. Sowing of nursery was completed between May 15, 2019 and May 23, 2019 however, seedlings were transplanted in the well prepared field during 05-20 June, 2019. Results of the present study clearly depicted the role of weather parameters on plant height, effective tillers, grain yield and spikelet sterility in the rice crop. High temperatures have detrimental effects on fertility of rice varieties, regardless the transplanting time. Among different rice cultivars, sterility was the lowest (17.8%) in PR121 and the highest 42.6% in PR129. Apart from the varietal differences, the lowest sterility 28.4% recorded in medium textured soil was lowered by 21.5% and 27.8% than light and high textured soils. Cultivar PR121 produced 3.9%, 7.7% and 15% higher grain yield than PR128, PAU201 and PR129, respectively. The response of anthesis period thermal stress on spikelet sterility should be considered to develop the temperature tolerant varieties for addressing the climate change issues.