Fahad Alghabari

Exogenously Applied Plant Growth Regulators Enhance the Morpho-Physiological Growth and Yield of Rice under High Temperature

A 2-year experiment was conducted to ascertain the effects of exogenously applied plant growth regulators (PGR) on rice growth and yield attributes under high day (HDT) and high night temperature (HNT). Two rice cultivars (IR-64 and Huanghuazhan) were subjected to temperature treatments in controlled growth chambers and four different combinations of ascorbic acid (Vc), alpha-tocopherol (Ve), brassinosteroids (Br), methyl jasmonates (MeJA), and triazoles (Tr) were applied. High temperature severely affected rice morphology, and also reduced leaf area, above-, and below-ground biomass, photosynthesis, and water use efficiency, while increased the leaf water potential of both rice cultivars. Grain yield and its related attributes except number of panicles, were reduced under high temperature. The HDT posed more negative effects on rice physiological attributes, while HNT was more detrimental for grain formation and yield. The Huanghuazhan performed better than IR-64 under high temperature stress with better growth and higher grain yield. Exogenous application of PGRs was helpful in alleviating the adverse effects of high temperature. Among PGR combinations, the Vc+Ve+MejA+Br was the most effective treatment for both cultivars under high temperature stress. The highest grain production by Vc+Ve+MejA+Br treated plants was due to enhanced photosynthesis, spikelet fertility and grain filling, which compensated the adversities of high temperature stress. Taken together, these results will be of worth for further understanding the adaptation and survival mechanisms of rice to high temperature and will assist in developing heat-resistant rice germplasm in future.

Rice Crop Responses to Global Warming: An Overview

The mean temperature might rise up to range of 2.0–4.5 °C worldwide by the end of this century. Beside from this, a prediction has been made that rise in minimum night temperature will be at a quicker rate as compare to the maximum day temperature. Rising temperatures not only affect the crop growth process, but also lead to direct changes in other environmental factors and pose indirect effect on yield and quality of rice has been observed, so at the present stage, it aroused public attention. Breeds, including through breeding and biotechnology to improve high temperature tolerance of rice help to mitigate the negative effects of high temperature, however, progress in this area have been slow. By adopting different methods like sowing, water and nutrient management can also to some extent mitigate the effects of high temperature on rice performance, but in most cases, these techniques are influenced by many factors, such as crop rotation, irrigation and other constraints like their applications are hard to applied to large area. Therefore, this chapter addresses (1) empirical reduction of rice yield (2) highlights the key significant mechanisms that influence main grain quality attributes under high temperature stress (3) inducing stress resistance and adopting mitigation strategies for high performance of rice.

Evaluation of Molecular Mapping Population from Wheat/Synthetic Hexaploid Cross for Drought Tolerance

To enhance the breeding efficiency in stress prone environments globally several molecular mapping populations have been produced. The focus of current study was to evaluate the mapping population derived from the cross of drought susceptible OPATA and drought tolerant synthetic hexaploid wheat. After field screening the selected genotypes were evaluated under in vitro conditions for physiological parameters like proline accumulation, chlorophyll content and SOD activity. Although, physiological evaluation has marked all these genotypes as drought tolerant but the performance of lines lines L-14, L-17, L-23, L-55, L-87, L-80, L-78, L-108, L-118, L-122, L-150 and L-152 was notable owe to their better physiological defense mechanism to drought. The present study concluded that unique genetic diversity from Aegilops tauschii (D genome donor) can be harnessed to get more yield by improving the existing cultivars against abiotic stress.

Combining Ability Analysis and Gene Action Studies of Different Quantitative Traits in Sunflower by Line x Tester

Four CMS lines and four restorers were crossed in a line x tester fashion to elucidate the information on the combining ability of seed yield, yield components and also to know the nature of gene action involved in inheritance of important quantitative traits. A total of 16 crosses were evaluated for eight different quantitative traits. Line CMS-HA-03 and CMS-HA-54 exhibited maximum GCA effects for most of the characters studied and were found to be the good general combiners. Likewise, tester RHP-73 was the good general combiners for most of the traits under study. Similarly cross combinations viz., CMS-HA-111 × RHP-71 and CMS-HA-03 × RHP- 76 were observed as potential cross having desirable SCA values.The estimates of variance components revealed predominance of non-additive gene action for all characters studied except days tomaturity.