Aegilops ovata: a potential gene source for improvement of salt tolerance of wheat

Abstract

Salt tolerant accessions of Ae. ovata were selected for hybridization with different tetraploid wheat varieties (Triticum durum). The F1 hybrids were top crossed with different hexaploid wheat cultivars. The 42 chromosome advanced derivatives (mostly BC2F3) were tested on artificially saline fields located at NIAB and ranging in ECe between 8–10 dS.m−1. The experiment was conducted during 1995–96 in a Randomized Complete Block Design with three replications. The objectives were to transfer salt tolerant gene(s) from Ae. ovata to cultivated wheat varieties and to diversify the genetic base of exiting salt tolerant wheat germplasm to be grown on saline lands.For hybridization, simple emasculation (or clipping of florets for backcrossing) and pollination technique was employed. Immature embryos were rescued only where necessary. Cytological and morphologically stable advanced derivative (BC2F3) were tested on saline blocks using saline irrigation of EC15dS.m−1 made artificially. Data with respect to variation in crossability, back cross (top crossed) seed production and cytological status was collected during the growth period. Plants were harvested at maturity and data on total biomass grain yield and harvest index was collected. Results were statistically analyzed using Analysis of Variance and Duncan Multiple Range Test.Significant variation in crossability of tetraploid wheats with salt tolerant accessions of Ae. ovata that ranges between 10–30% seed set were observed. Maximum seed set (30%) was obtained for crosses of wheat variety Durum with Ae. ovata acc. 65 while minimum crossability values were obtained for crosses of Akrache-2 with Ae. ovata accession 276978. Within the wheat varieties, variation in crossability of a particular accession of Ae. ovata was not significant while between different Ae. ovata accessions, variation in crossibility with any particular wheat variety was significant. Topeross seed production also showed significant variation which ranged between 10% (H-19/Ae.ovata: 369580//Pasban-90) as minimum and 40% as maximum in H-19/Ae.ovata // Pasban-90.Production of biomass and grain yield under saline field was significantly different from biomass and grain yield obtained under non-saline control. Harvest index of advanced derivatives on the other hand improved. Within the saline and non saline (control) fields the difference in biomass production (7570–9377 kg.h−1) between different derivatives was generally non-significant however, difference for grain yield which ranges between 1088–2701 kg/h was highly significant. When the grain yield and biomass of hexaploid wheat varieties growing under the same saline and non-saline control was compared with the advanced derivatives, the differences were again highly significant. It was interesting to note that when the advanced derivatives were grown under saline field, reduction as compared to control in biomass and grain yield was 39.40 and 21.50% respectively. However, when hexaploid wheat line were grown under saline fields, the reduction in biomass and grain yield as compared to control was 49.37 and 64.82% respectively and difference between the two was highly significant. The results indicated the anticipated transfer salt tolerant gene(s) from Ae. ovata to hexaploid wheat. Possibility of using the germplasm for cultivation of saline lands would be discussed with special reference to significance of Ae. ovata in wide hybridization.Key wordsAegiolops ovataHexaploidHybridizationSalt tolerant gene