In Egypt, the impact of high temperatures on tomato production during summer season has become an urgent issue. Where the day/night temperature rising above the optimal for flowering and fruit set, consequently, the fresh market tomato prices increase about 400 to 500% during this period with inferior quality of fruits. The objective of this work was to assay new genetic resources of a set of ex situ lines and cultivars for heat-tolerant. Furthermore, selection for promising parents that would be used in developing more adaptive cultivars to heat stress. All experiments were carried out during 2013 to 2015. Fifty tomato genotypes (Lycopersicon esculentum, Mill.) were evaluated in a randomized complete blocks design under the natural heat stress conditions. The following traits; plant height, number of branches, leave area, fruit set %, total chlorophyll, chl a/b ratio, chl T/carotenoid, in addition to yield and some fruit quality traits were estimated. Based on the phenotypic performance and the genetic divergence of these genotypes, 10 parental varieties were selected for a factorial mating design using 6 as males and 4 as females. High genetic variability was observed among the genotypes for all studied traits. Mean of fruit set % ranged from 12.7 % to 66.5%. Twelve genotypes gave more than 50kg/plot where the genotypes LA0535 and BGH-0226 recorded the highest mean values of 63.15 and 61.88 kg/plot, respectively. The mean squares of GCA as well as SCA were significant for the majority of studied traits indicting the importance of both additive and non-additive types of variation for all studied traits. Among the female lines, BGH-2004 exhibited maximum positive gi effect, while among the male lines, BGH-0226 displayed highest gi effect for plant height. The cross resulted from BGH-3474 x BGH-0226 gave the highest Sij effect for fruit set % indicating that the female line BGH3474 and tester BGH-0226 produced promising progenies for vegetative traits and fruit set improvement. While the female line BGH-3474 and male line BGH-7466 gave the highest gi effects for total yield per plot. According to the variation and diversity analysis, the genotype LA0535 from group I showed stable high yield across the two summer seasons 2014 and 2015 and was a good donor for fruit set, TSS and firmness however its poor fruit in lycopene. The hybrid 2x5 showed high adaptation against heat stress under field condition in 2015 with high total yield, leave area number of branches per plant, average fruit weight and fruit firmness but low lycopene. Therefore, for hybridization program, crosses among LA0535, BGH-0025, BGH-7466 for heat tolerance and yield could be effective and promising.
This study aimed to identify new rice lines and hybrids that are tolerant to water deficit and produce high yields under water stress conditions. A line × tester mating design was used to study the lines and testers’ general combining ability (GCA) effects. The specific combining ability (SCA) of the hybrid rice combinations was measured under three different irrigation regimes; 6, 9, and 12 days. The study was carried out at the experimental farm of Sakha Agricultural Research Station, Sakha, Kafr El-Sheikh, Egypt, during the 2018 and 2019 rice growing seasons. Due to the genotypes and their partitions to the parents and the crosses, the mean squares were highly significant for all studied traits under the three irrigation regimes. The additive gene effects play an important role in expressing most of the studied traits. Therefore, the selection procedures based on the accumulation of the additive effect would be successful at improving these traits and the grain yield. The cytoplasmic male sterile (CMS) line G46A (L1) was the best combiner for most yield component traits in the three irrigation regimes. The newly devolved restorer lines T11, T1, T2, T5, T4, and T3, as well as the new hybrids L2 × T10, L2 × T6, L1 × T7, L1 × T5, L1 × T3, L2 × T7, L2 × T9, L2 × T8, L2 × T4, L1 × T4, L2 × T2, L1 × T8, L1 × T9, and L2 × NRL 10, showed good, desirable values of the studied traits such as earliness of flowering, short plant height, number of panicles/plant, panicle length, number of spikelets/panicle, number of filled grains/panicle, panicle weight, 1000-grain weight, hulling percentage, milling percentage, head rice percentage, and grain yield under the irrigation regimes of 6, 9, and 12 days. The hybrids L2 × T10, L2 × T6, L1 × T7, and L1 × T5, showed significant positive SCA effects for grain yield, under all three irrigation regimes.
Background Wheat is the most important crop around the world. Drought stresses affect wheat production and their characterization. Most of the traits that are affected by drought are quantitative traits, so detection of the quantitative trait’s loci (QTLs) related to these traits is very important for breeder and wheat producers. In this trend, 285 F2 individuals from crosses between four bread wheat genotypes (Triticum aestivum L.), i.e., Sakha93, Sids1, Sakha94, and Gemmiza9, were used for identified QTLs associated with plant height (PH) and leaf wilting (LW). Single marker analysis and composite interval mapping (CIM) were used. Results A total of 116 QTLs loci were detected which covered 19 chromosomes out of the 21 chromosomes of wheat. PH and LW had 74 and 42 QTLs loci, respectively. On the other hand, chromosome 7A showed to bear the highest number of QTLs loci (15 loci). While chromosome 1A beard the highest number of QTLs loci related to PH (10 loci), chromosome 2B and 7A beard the highest number of QTLs related LW. We highly recommend our finding to help breeders in wheat breeding programs to improve plant height and leaf wilting. Conclusion Our investigation concluded that SSR markers have high efficiency in the identification of QTLs related to abiotic stress; also the CIM method had more advanced priority for QTLs mapping.
Background The improvement of maize hybrids relies on significant genetic variability among the inbred lines used and the degree to which it is transferred to progeny. Understanding the genetic parameters and heritability of traits in every population is an essential precondition for selection program. This study was designed to estimate the magnitude of genetic parameters and heritability of traits in line × tester mating design. Fifteen yellow maize inbred lines derived from different sources were crossed with two lines as tester i.e., Gm-1001 and Gm-1002 in 2019 summer season. During 2020 season, the resulted 30 crosses along with check hybrid SC-168 were evaluated in a yield trial at two locations: Gemmeiza and Sids Agric. Res. Station. Results The mean squares among two locations were highly significant for all studied traits except KR−1. The L1 and L3 had the best general combiners for GY ard fed−1. In addition, the T1 as a tester was a GCA effects good combiner for earliness, shorter plants and lower ear placement traits. While T2 was good combiner for grain yield and some of attributes. Crosses L5 × T1 and L7 × T2 had positive and significant SCA effects for grain yield. The GCA variances were higher than SCA variances for all studied traits except for ED trait, indicating that additive genetic variance played the major role than non-additive genetic variance in the inheritance of these traits. Generally, phenotypic coefficient of variability was higher than genotypic coefficient of variability for all studied traits, suggesting that there was an influence by environments in the expression of these traits. Recorded heritability percentage in broad sense ranged from low for (ear position%, no. of ears/100 plants, ear diameter and grain yield) traits, medium for (days to 50% silking, plant height, ear height and no. of kernels/row) traits to moderate high for ear length trait. Conclusion Our investigation concluded that most of the studied lines exhibited highly general combiners and the superior crosses were as a result of a good × good combiner for most of yield components traits.
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