Genetic variability of leaf net photosynthesis rate (An) and its relation to productivity in durum wheat (Triticum turgidum L. var. durum) is not well defined. Two field experiments were conducted at the experimental area of the Faculty of Agriculture, in the University of Çukurova, Turkey, to evaluate the differences between old and modern cultivars in An and productivity. Experiments with sowing dates in November 1996 and February 1997 were performed under rainfed and irrigated conditions, respectively. Measurements included leaf gas exchange and agronomic traits. Old cultivars (OC) were later flowering and taller than modern cultivars (MC) and their harvest indexes were lower. Before the onset of leaf senescence, most of the OC exhibited higher An values than most of the MC, but the extent of variability was not great. High An was correlated with high stomatal conductance (gs), but no overall correlation between An and the ratio of internal [CO2] to [CO2] in the air was observed. In spite of higher An, OC showed no superiority in grain yield. The results indicate that mesophyll conductance rather than gs has an effect on variation in An, and that preanthesis dry matter distribution and total flag leaf photosynthesis and its duration appear to be more relevant than An for grain yield, especially under drought.

This study was conducted to determine the reciprocal effects for anther culture response in wheat (Triticum aestivum L.) using a set of 4 × 4 full diallel crosses. Both reciprocal and nuclear genetic effects were highly significant for anther culture response and useful for selection and breeding purposes. General combining ability (GCA) effects were predominant for all investigated anther culture traits. Also, significant differences for specific combining ability (SCA) effects were detected between reciprocal crosses. Although significant reciprocal differences for responding anther, callus number and green plant regeneration were recorded in some reciprocal crosses, there were no significant reciprocal differences for albino plant regeneration. The use of one parent as male or female could lead to change at the production of green plants from the F 1 hybrids and screening of inbred lines for response to anther culture, without reciprocal effects, could decrease the utilization of breeding material.

No abstract

The development of triticale (X Triticosecale Wittmack) cultivars which are tolerant to drought and heat stress is an objective in many breeding programmes, but so far success has been limited. This study was conducted to determine the susceptibility index (S) of triticale under stress conditions. Twenty genotypes were grown in replicated trials and evaluated for heat and drought tolerance under natural conditions at Adana, Turkey, from 1992 to 1996. Among the advanced lines of triticale, genetic variation for adaptation to heat and drought conditions—typical features of the Mediterranean environment—was determined. The best yielding lines under stress, hence having a low susceptibility index, were Lynx/Yogui and Zebra 31. The implications of these findings for triticale breeding in stress environments are discussed.

Due to high production cost and prevention of environmental pollution, it is important to reduce the amount of nitrogen (N) fertilizer used on wheat (Triticum aestivum L.). The aim of this study was to evaluate N use of 6 × 6 diallel wheat F 2 progenies and parental lines at low (N0, no N fertilizer) and high (N+, 160 kg N ha −1 ) N levels. Significant differences were found between N+ and N0 application in grain N content, grain N yield, N use efficiency for grain N yield (NUEgn), and N use efficiency for grain yield (NUEgy). The cultivar '84Ç ZT04' showed positive and high general combining ability (GCA) effects for all traits at low N level. Also, it was the best combiner for all traits at both N levels. The cultivar 'Genç 99' was the best parent for GCA effects for grain yield and NUEgy. Hybrids 'Genç 99 × 84Ç ZT04' and '84Ç ZT04 × Weaver' showed positive specific combining ability (SCA) effects for all investigated traits at low and high N levels. Variety '84Ç ZT04 × Apogee' had the best SCA effects for all traits at low N level. Overall, the data suggest that it is probable to select promising lines suitable for low N conditions by the crossing of high N use efficient parents.