Improvement of drought tolerance in rice using line X tester mating design and biochemical molecular markers

Background Water stress, specifically the limited water resources needed to grow strategic crops, especially rice, poses a great threat to crop productivity. So, it was imperative that scientists all work together to try genetically improving the rice for drought tolerance in light of these environmental challenges. The aim of this study is trying to know the genetic behavior responsible for water-deficit tolerance in rice genotypes but at the molecular level. Moreover, this attempt will be an important leap in the process of genetic improvement in rice for water stress tolerance in Egypt. Results Twenty-three rice genotypes including eight parents and their fifteen F1 crosses or (the first hybrid generation) by line X tester analysis were evaluated for water stress tolerance during two experiments (the control and drought experiment) besides some molecular–biochemical studies for eight parents and the highest selected five crosses for water stress tolerance. The research revealed that five rice crosses out of fifteen hybrids were highly tolerant to water stress compared to the normal conditions. Data of biochemical markers indicated the presence of bands that are considered as molecular genetic markers for water-deficit tolerance in some rice genotypes, and this is the scientific progress achieved in this research. This was evident by increasing the density and concentration of SDS-protein electrophoresis besides enhancing the activities of peroxidase (POD) and polyphenol oxidase (PPO) under water-deficit conditions, which confirmed the tolerance of drought stress in the eight rice genotypes and the best five crosses from the first hybrid generation. Conclusion The five promising and superior rice hybrids showed an unparalleled tolerance to water stress in all evaluated traits under water stress treatment compared to the standard experiment. Also, biochemical and molecular parameters evidence confirmed the existence of unquestionable evidence that it represents the main nucleus for producing rice lines tolerated for drought stress under Egyptian conditions.

Stability Analysis of Rice Hybrids for Grain Yield in Telangana through AMMI and GGE Bi-plot Model

An investigation was carried out on fifteen rice genotypes to identify stable rice hybrids across six different agroclimatic zones in Telangana state using AMMI and GGE bi-plot analyses during July to November, 2020. Analysis of variance clearly showed that environments contributed highest (65.47%) in total sum of squares followed by genotypes×environments (21.19%) indicating very greater role played by environments and their interactions in realizing final grain yield. AMMI analysis revealed that rice hybrids viz., RNRH 39 (G6), 27P31 (G14) and RNRH 15 (G1) were recorded higher mean grain yield with positive IPCA1 scores. The hybrids, JGLH 275 (G11) and JGLH 365 (G15) were plotted near to zero IPCA1 axis indicating that these hybrids are relatively more stable across locations. GGE bi-plot genotype view depicts that the hybrids, JGLH 365 (G15) and US 314 (G8) were inside the first concentric circle and found to be more stable across environments. GGE bi-plot environment view showed that Rudrur (E4) location was the most ideal environment. However, Warangal (E6) and Jagtial (E1) locations were poor and most discriminating. Depending on dispersion of environments in different directions, six locations were partitioned into three mega zones as first zone comprised of four locations viz., Kunaram (E2), Kampasagar (E3), Rudrur (E4) and Rajendranagar (E5) whereas highly dispersed Jagtial (E1) and Warangal (E6) were identified as two separate mega environments. The bi-plot view identified that 27P31 (G14), JGL 24423 (G2) and RNRH 39 (G6) were the best performing genotypes in first zone comprising four locations.

Introduction of special rice genotypes under upland conditions

Although widely consumed as white rice, there are special rice cultivars that contain aromas, colors and nutrients that reach special market niches, and constitute alternatives to vary the Brazilian menu and the farmer’s income. Most genotypes of special rice have nutritional characteristics superior to those of white rice, with call for better health, which is a growing concern of the general population. Based Based on these assumptions, the objective was to evaluate the productivity of special rice genotypes in rainfed cultivation conditions, in two seasons (2016/2017 and 2017/2018), in the city of Lavras/MG The treatments consisted of the following accessions: YIN LU 31, Japanese, CMG 1164, Formoso, Aromatic, IAC 400, IAC 300, IAC 600, IAC 500, BRSMG Relâmpago, BRSMG Caçula, BRSMG Caravera, SCS119 Ruby, SCS120 Onyx. After analysis of variance, the adaptability analysis and stability was performed by the Annichiaric method. The Aromatic and IAC 300 genotypes, by evaluated under rainfed conditions, showed high productivity (greater than 3,000 kg.ha-1), higher than the state average (867 kg ha-1), and low incidence of diseases in the conditions of high lands. These special rice genotypes grown in upland and compared to cultivars of rice indicated for this cultivation condition demonstrated that it is possible to produce rice from quality and develop genotypes more adaptable to rainfed conditions, which can be excellent option of cultivation to conventional rice and thus increase the diversity of the agricultural property.

GENETIC VARIABILITY FOR GRAIN NUTRIENTS CONTENT IN COASTAL RICE COLLECTIONS OF BANGLADESH

Overcoming malnutrition through biofortification breeding in rice is aimed to assist nutritional food security in Bangladesh. So to select parents for nutritional improvement, estimation and exploitation of mineral nutrients reserves of rice grain and their variability assessment in different genotypes is essential. Eighty-five (85) T. aman rice genotypes collected from different coastal regions of Bangladesh were evaluated at the Advanced Plant Breeding laboratory, GPB of BSMRAU to estimate the grain nutrients content and to elucidate their genetic variability among the genotypes. Considerable significant variation (0.1% level of probability) was noted among the genotypes for studied different grain nutrient contents and yield per hill. The mean values of N, P, K, Ca, Mg, Na, Zn, Fe, Cu, Mn and grain yield/ hill were 10788.24 mg/kg, 804.85 mg/kg, 3798.58 mg/kg, 13795.29 mg/kg, 2778.87 mg/kg, 3771.17 mg/kg, 7.25 mg/kg, 5.01 mg/kg, 1.05 mg/kg, 1.90 mg/kg and 433.29 g, respectively. Box and whisker plots analysis were done to represent data graphically for better understanding. Histogram was used to present the frequency distribution of genotypes for N, P, K, Ca, Mg, Na, Zn, Fe, Cu, Mg and Grain yield/hill content in 85 diverged rice genotypes All the traits had equality in genotypic and phenotypic variances with high heritability and high genetic advance which indicated preponderance of additive gene effects for these traits. The genotype R080 (Chinigura) contained the highest content of grain P, Fe and Cu. The R030 (Mota Dhan), R040 (Dudh Kalam) and R019 (Chikon Dhan) were noted for the highest Ca, Mg and Na content, respectively. The maximum N and Zn content were observed in R029 (Dudh Kolom) and R075 (Gopal Bogh), respectively. R083 (Lal Dhan) was marked for the highest grain yield/ hill and K content. Genetic variability parameters, heat map analysis and neighbor joining clustering methods indicated these genotypes including R079 can be considered for biofortification program and used as parents for the improvement of those grain nutrients in rice breeding.

The different responses of rice genotypes to heat stress associated with morphological, chlorophyll and yield characteristics

Sixteen rice genotypes were planted under normal and high temperature during 2018 and 2019 seasons to understand the mechanisms that make plants tolerant or susceptible to heat stress and methods which may lead to generate new varieties with sustainable yield production. The combined analysis showed significant differences at the level of probability 0.05 and 0.01 among years for all characters except, chlorophyll content and leaf rolling which would indicate wide differences among the weather of both years. Environment’s variance was significant at the level of probability 0.01 over all characteristics. The significant differences at the level of probability 0.01 were recorded among genotypes and G x E interaction variances for all characteristics. The highest values of panicles number plant-1 were obtained from ‘Giza 178’ and ‘Hybrid 2’, however, the highest values of 100-grain weight were recorded with ‘Giza 179’ and ‘Egyptian Yasmine’. The minimum values of sterility% were recorded with ‘Sakha 107’ and ‘IET1444’. Concerning the cultivars performance across two environments, the cultivars ‘Giza 178’, ‘Giza 179’, ‘Sakha 107’ and ‘IET 1444’ gave the best desirable values over natural and heat stress so, those cultivars are considered to play a vital role in breeding program to enhance heat stresses tolerance accompanied with high yield potential.