Effect of moisture regimes on combining ability variations of seedling traits in sunflower (Helianthus annuus L.)

Abstract

. 2008. Effect of moisture regimes on combining ability variations of seedling traits in sunflower (Helianthus annuus L.). Can. J. Plant Sci. 88: 323Á329. Seedlings traits provide a reliable and rapid technique for evaluating large numbers of genotypes for abiotic stresses. Experiments on sunflower were carried out under two moisture regimes in controlled conditions to study their modifying effect on phenotypic expression and combining ability of seedling traits such as root length (RL), shoot length (SL), root weight (RW), shoot weight (SW), root-to-shoot ratio (R:S), lateral root number (NLR), lateral root density (LRD), wilting rate index and recovery percent (R%), and their genotypic correlation with achene yield. Variation among breeding lines for relative decrease in the seedling traits under the moisture stress regime indicated their differences in moisture sensitivity. Genetic variation for all seedling traits was low over environments, but high within environments. Moisture regimes modified phenotype, ranking among parents, and combining ability of seedling traits. Relative contribution of specific combining ability to total variation decreased under the moisture stress regime for all root-based traits, with a corresponding increase in general combining ability due to either female, male or both. The moisture stress regime was favourable for the expression of additive genetic variability. All seedling traits except SL showed significant correlation with achene yield, which also signified their importance for improving achene yield under drought regimes. From the breeding point of view, R% and RW were more useful traits for evaluating genotypes for drought tolerance.Key words: Sunflower, seedling traits, genetic variability, drought tolerance Rauf, S., Sadaqat, H. A. et Khan, I. A. 2008. Incidence de l'humidite´sur la variation des aptitudes a`la combinaison des caracte`res de la plantule chez le tournesol (Helianthus annuus L.). Can. J. Plant Sci. 88: 323Á329. Les caracte`res de la plantule permettent d'e´valuer rapidement et de manie`re fiable un grand nombre de ge´notypes en fonction des stress abiotiques. Les auteurs ont proce´de´a`des expe´riences sur le tournesol en milieu controˆle´, sous deux re´gimes hygrome´triques, en vue de pre´ciser l'incidence de l'humidite´sur l'expression phe´notypique et la combinaison de divers caracte`res tels la longueur des racines, la longueur des pousses, le poids des racines, le poids des pousses, le ratio entre racines et pousses, le nombre de pousses late´rales, la densite´des pousses late´rales, l'indice de fle´trissement et de re´cupe´ration ainsi que leur corre´lation ge´notypique avec le rendement en ake`nes. La variation des ligne´es au niveau de l'affaiblissement relatif des caracte`res de la plantule conse´cutivement a`un stress hygrome´trique re´ve`le leur sensibilite´al 'humidite´. La variation ge´ne´tique des caracte`res de la plantule demeure faible d'un milieu a`l'autre, mais est e´leve´e au sein d'un meˆme environnement. Le re´gime hygrome´trique mo...

Characterization of Cotton (Gossypium hirsutum) Germplasm for Drought Tolerance using Seedling Traits and Molecular Markers

“…It is particularly true when the breeding program is targeting the water stress tolerance (Khan et al, 2008;Jajarmi, 2009;Qayyum et al, 2011). Among different seedling traits, root characteristics play an important role for carrying out different physiological processes for plant growth such as uptake and assimilation of nutrients, stress signals about water deficit stress and movement of water from soil to plant (Rauf and Sadaqat, 2008;Bibi et al, 2012). Therefore, root length could be used for rapid and early screening of large amount of germplasm against water stress.…”

Prospects of Inducing Resistance in Fodder Species against Toxic Ions and Metals

“…Various screening criteria and conditions have been proposed for screening cultivated germplasms (Noorka and Khaliq 2007;. Among various screening criteria, seedling traits have been identified as an efficient way to screen germplasms (Rauf and Sadaqat 2008;Rauf et al 2010). In addition, the germplasm is exposed to more uniform conditions in comparison with field conditions where significant soil and climate heterogeneity exits.…”

In vivo evaluation of wheat (Triticum aestivum L.) cultivars for moisture stress

“…According to Boureima et al (2011), good germination capacity and seedling growth in water deficit conditions are drought tolerance indices, which allow better prediction on the crop establishment. In addition, field experiments related to water stress has been difficult to handle due to significant environmental or drought interactions with other abiotic stresses (Rauf et al, 2008). An alternative approach is to induce water stress through polyethylene glycol 6000 (PEG 6000) solutions for screening of the germplasm (Khodarahmpour, 2011).…”