generation mean analysis of drought tolerance in wheat (triticum aestivum l.)

Acta Agronomica Hungarica, 49(1), pp. 59–66 (2001)

0238–0161/2001/$ 5.00©2001 Akadémiai Kiadó, Budapest

GENERATION MEAN ANALYSIS OF DROUGHTTOLERANCE IN WHEAT (TRITICUM AESTIVUM L.)

E. FARSHADFAR, M. GHANADHA1, M. ZAHRAVI and J. SUTKA2

COLLEGE OF AGRICULTURE, RAZI UNIVERSITY, KERMANSHAH, IRAN1COLLEGE OF AGRICULTURE, TEHRAN UNIVERSITY, TEHRAN, IRAN

2AGRICULTURAL RESEARCH INSTITUTE OF THE HUNGARIAN ACADEMY OF SCIENCES,MARTONVÁSÁR, HUNGARY

Received: 3 July, 2000; accepted: 15 January, 2001

To evaluate the genetic background of quantitative criteria of drought tolerance inwheat, six generations of a cross between the varieties of Plainsman and Cappelle Desprezwere grown in a randomized complete block design with three replications in thegreenhouse of the College of Agriculture of the University of Tehran in 1997.

Genetic variation was found for yield potential (Yp), stressed yield (Ys), excised leafwater retention (ELWR), relative water loss (RWL), relative water content (RWC) andharvest index (HI) under water stress conditions.

High heterosis and heterobeltiosis were observed in the F1 hybrid for Ys, HI andspike yield index (SYI). Genetic analysis exhibited overdominance in the inheritance ofYs, RWL, ELWR, HI, biomass and SYI, while RWC and Yp were controlled by theadditive type of gene action. High narrow-sense heritability estimates were shown byELWR, biomass and SYI. The high genetic advance for ELWR, RWC, HI and SYIindicated that direct selection could be effective for these traits. The epistatic effects(additive × additive=[i] for Yp, Ys and RWL, additive × dominance=[j] for ELWR, anddominance × dominance =[l] for RWL) were found to be outstanding.

Key words: wheat (T. aestivum L.), drought tolerance, stress tolerance index, geneaction, scaling test

Introduction

Among the environmental stresses drought is the second contributor toyield reduction after disease (Farshadfar et al., 1995; Kristin et al., 1997). Toimprove the drought resistance of a crop, the most important step is tounderstand the mode of inheritance, the magnitude of gene effects and theirmode of action (Bushuk et al., 1989; Acevedo and Ceccarelli, 1989; Snape,1987). Many workers developed genetic models for the estimation of differentgenetic effects (Gamil and Saheal, 1986; Kearsey and Pooni, 1996). Acomprehensive review of the evaluation of the genetic components of variationwas presented by Haluver and Miranda (1985). In most of these methods onlyone generation is employed, but in generation mean analysis, the mean ofdifferent generations is used to calculate genetic effects (Haluver and Miranda,1985). A general method of testing the expected relationships betweengenerations using an additive dominance model was proposed by Cavalli (1952)and illustrated by Mather and Jinks (1982). A significant difference was foundfor the drought tolerance criteria wheat varieties Plainsman (drought-tolerant)