Physiological and molecular insights into the allelopathic effects on agroecosystems under changing environmental conditions.

Allelopathy is a natural phenomenon of competing and interfering with other plants or microbial growth by synthesizing and releasing the bioactive compounds of plant or microbial origin known as allelochemicals. This is a sub-discipline of chemical ecology concerned with the effects of bioactive compounds produced by plants or microorganisms on the growth, development and distribution of other plants and microorganisms in natural communities or agricultural systems. Allelochemicals have a direct or indirect harmful effect on one plant by others, especially on the development, survivability, growth, and reproduction of species through the production of chemical inhibitors released into the environment. Cultivation systems that take advantage of allelopathic plants' stimulatory/inhibitory effects on plant growth and development while avoiding allelopathic autotoxicity is critical for long-term agricultural development. Allelopathy is one element that defines plant relationships and is involved in weed management, crop protection, and microbial contact. Besides, the allelopathic phenomenon has also been reported in the forest ecosystem; however, its presence depends on the forest type and the surrounding environment. In the present article, major aspects addressed are (1) literature review on the impacts of allelopathy in agroecosystems and underpinning the research gaps, (2) chemical, physiological, and ecological mechanisms of allelopathy, (3) genetic manipulations, plant defense, economic benefits, fate, prospects and challenges of allelopathy. The literature search and consolidation efforts in this article shall pave the way for future research on the potential application of allelopathic interactions across various ecosystems.

Comparative response of rice cultivars to elevated air temperature in Bhabar region of Indian Himalaya: status on yield attributes.

Increasing atmospheric temperature is the consequence of global warming, which is expected to influence crop growth and development, resulting in declining productivity in the tropical agriculture system. The selection of temperature tolerant crop cultivars with higher productivity to meet the future demand of the world expanding human population requires a thorough understanding of crop growth feedback to increasing temperature. Therefore, a field experiment was conducted during the Kharif season of 2012 and 2013 to understand the response of yield and yield-related traits of eleven rice cultivars to elevated temperature grown inside field mounted temperature gradient tunnel (TGT) in the Bhabar region of the Indian Himalayas. The elevated temperature significantly impacted growth and yield and yield-related traits, especially tillers, panicles, filled and chaffy grains, grain, and 1000 grain weight, yield, and harvest index of all the cultivars during both years. The cultivars, i.e., IET 21404 and IET 21577, were reported to produced more tillers in 2012, whereas IET 21411 and KRH 2 had a maximum 2013. Likewise, maximum panicles were reported in IET 21404 and IET 21577 in 2012, while IET 21411, IET 21582, and KRH 2 in 2013 under elevated temperature. The highest grain filling under high temperature in 2012 was found in IET 21577, then IET 21404; however, IET 21411 and IET 21405 were the highest filled grains in 2013. Consequently, the cultivars IET 21577 and IET 21404 were reported as more tolerant towards yielding higher grain weight and Harvest Index. This study offers an opportunity to screen temperature tolerant cultivars with increased productivity for fulfilling the demand of rice-dependent regions in future changing climatic conditions.

Elevated temperature modulates rice pollen structure: a study from foothill of Himalayan agro-ecosystem in India.

Rice cultivation is practiced in various agro-climatic zones ranging from tropical to temperate. Anthesis is a critical stage for deciding productivity which is controlled by numerous biotic and abiotic stresses. Elevated temperature is one of the key abiotic stresses that adversely modulate the pollen formation and structure, i.e., infertility, results in productivity decline. The present study was conducted to investigate the effects of elevated temperature on morphological changes in pollen grains of rice grown in temperature gradient tunnel (TGT) constructed in filed condition. The ambient and TGT temperature varied from 31.84 °C(max) to 20.56 °C(min) and 41.91 °C(max) to 22.37 °C(min), respectively, during study period. The scanning electron and light microscopic study showed extreme morphological abnormalities viz. shape and size in pollen grains of rice exposed to elevated temperature as compared to ambient. These abnormalities induced by elevated temperature may drastically decline grain filling potential which ultimately reduces grain yield in future climate change. This study will enlighten rice researchers for further screening of rice genotypes thermotolerant to foothills of Himalayan agro-ecosystem.