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Yanhong Lou, Liang Chen, Qingguo Xu, and Xunzhong Zhang

, spike count per plant, and spike weight are major components of plant yield as selection criteria in breeding ( Topal et al., 2004 ). Ebrahimiyan et al. (2012) reported significant genotypic variation in plant height, flag-leaf length, and flag

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Aidan D. Farrell, Sarah Evelyn, Adrian M. Lennon, and Pathmanathan Umaharan

reduced ability to retain water in the floral organ as senescence begins ( Solomos and Gross, 1997 ). As such, genotypic variation in vase life may be driven by water supply or by the senescence response in the bloom. It is currently unclear whether

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Xin Song, Suo-min Wang, and Yiwei Jiang

in perennial ryegrass. Therefore, the experiment was designed to identify the genotypic variations in growth traits and nutrient elements in relation to salinity tolerance in perennial ryegrass. The results would provide insights into variability of

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José J.M. van der Meulen-Muisers, Joop C. van Oeveren, and Jaap M. van Tuyl

Genotypic variation in postharvest flower longevity was determined for 63 Asiatic lily hybrids (Lilium L.). The reliability of standardized test conditions for longevity screening was also examined. Improvement of lily flower longevity by breeding appears feasible. Considerable genotypic variation in individual flower longevity was obtained and estimates of the degree of genotypic determination were high. The rank order of the genotypes with respect to individual flower longevity was similar between years using standardized test conditions. Screening results for flowers forced in a growth chamber were similar to those obtained in a greenhouse. No plant traits suitable for indirect selection on flower longevity were detected.

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Douglas V. Shaw

Abstract

Genotypic variances and genotypic correlations were estimated for soluble solids content (SSC), titratable acids, and their major constituents, using strawberry genotypes (Fragaria × ananassa) not previously selected for flavor or other commercial traits. Genotypic variances estimated for SSC and total sugars were nonsignificant, whereas those estimated for acids were significant and large. Relative expression of acids was stable throughout the season; large genetic × harvest date interactions reduced genotypic consistency for SSC. Despite the absence of detectable genotypic variation for SSC and total sugars, significant genotypic variation was detected for sucrose, glucose, and fructose, and the relative expression of these sugars was stable over harvest dates. The total allocation of sugar to fruit appears fixed, but the distribution pattern among sugar constituents at commercial ripeness is variable. This interpretation was supported by the observation of a strong negative genotypic correlation between sucrose and its components, glucose and fructose. These results suggest that opportunity exists for genetic improvement of acids, but that selection response for SSC will be difficult to obtain.

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Toshihiro Saito, Norio Takada, Hidenori Kato, Shingo Terakami, and Sogo Nishio

Genotypic variations in and environmental variance components of the total sugar content (TSC) and sugar composition, including sucrose (SUC), fructose (FRU), glucose (GLU), and sorbitol (SOR), in the fruit juice of 13 Japanese pear cultivars were analyzed. The TSC of ‘Kanta’ and TSC of ‘Hoshiakari’ were high (both >14.5 g/100 mL). The contents of SUC and FRU were higher than those of the other sugars. The SUC contents were ranked as follows: ‘Gold Nijisseiki’, 7.3 g/100 mL; ‘Shuurei’, 6.2 g/100 mL; and ‘Akizuki’, 6.1 g/100 mL. The FRU content in ‘Kanta’ was the highest among all monomeric sugars evaluated (6.8 g/100 mL). These results suggest that ‘Kanta’ is superior in terms of both TSC and sugar composition, which determine sweetness. The yearly environmental variance components were negligible for all traits. The genotype × year ranged from 4.4% to 13.7% of the total variance. Within-tree variance was 17.1% for TSC, whereas that for the sugar composition ranged from 1.4% to 6.1%. The tree × year ranged from 2.7% to 7.4%. Variance among fruits within trees was the largest environmental variance component—except for FRU—and ranged from 8.8% to 35.6%. Broad-sense heritability (h B 2) values based on single tree, single year, and single fruit measurements were 0.33, 0.64, 0.69, 0.71, and 0.76 for TSC, SUC, FRU, GLU, and SOR, respectively. These results suggest that it would be easier to estimate genetic differences in sugar components with a higher level of precision than those in TSC. Increasing the fruit number up to five, in combination with yearly repetition increased to two (without tree repetition), significantly increased the h B 2 of all traits undergoing study. The information obtained during this study will be useful for improving the accuracy of phenotypic selection and future genomic-based breeding studies performed to improve the sweetness of Japanese pear fruits.

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Diheng Zhong, Hongmei Du, Zhaolong Wang, and Bingru Huang

‘Tifway’ maintained lower EL (67%) at the same level of water deficit (indicated by RWC) by the end of the drought period compared with ‘C299’ (85%), suggesting leaves of ‘Tifway’ had superior dehydration tolerance. Genotypic variation and the response of

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Renae E. Moran, Bryan J. Peterson, Gennaro Fazio, and John Cline

°C and a TI of −32 °C or higher ( Table 1 ; Fig. 3 ). V.5 had the greatest xylem Bmax, although most genotypes had values similar to V.5, except for ‘M.9’ and G.5087, which had a lower Bmax. Genotypic variation occurred in the TI, and ‘G.214’, G.3902

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Anke van der Ploeg, Susana M.P. Carvalho, and Ep Heuvelink

maintain high production levels year round. Cultivars that are better adapted to lower temperatures could contribute significantly to a reduction in energy use and consequently in CO 2 emission. For breeding of more energy-efficient cultivars, genotypic

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Jianming Sun, Yiming Liu, Xianglin Li, and Bingru Huang

Discussion Genotypic variations of tall fescue in physiological responses to drought stress. The previous study ( Sun et al., 2013 ) reported that RU9 had superior drought tolerance over RU18, as shown by the greater turf quality, relative water content, and