Abstract
To standardize an efficient protocol for the production of haploids in spring wheat, 10 genotypes of wheat were crossed with 3 maize varieties. Three concentrations of 2,4-D: 50 ppm, 100 ppm and 150 ppm were used as post pollination treatments. Pollination with the maize genotype resulted in fertilization in all the 10 wheat genotypes ranging from 17.70% to 33.55% (mean 23.34%). Caryopses development frequencies in the crosses ranged from 59.70% to 88.90% and embryo formation from 11.90% to 36.00%. Significant effects of wheat parents were observed for development of caryopses. There was a positive correlation between the formation of embryos and the production of developed caryopsis (r = 0.527). On average 18.29% (1984 embryos) of the 10, 848 pollinated florets produced embryos. Most of the embryos which failed to develop plantlets were small. In total, 479 out of 1984 embryos (4.42% of pollinated florets) produced plantlets. Significant differences were observed among the wheat varieties for haploid plant regeneration over embryos and over pollinated florets. The variety Sonora-64 produced the highest percent of haploid plants over embryos (34.02%) and over pollinated florets (14.95%). Maize pollinators did not show any significant effect for the parameters studied. Significant variations on development of caryopses, regeneration of plants over embryos and over pollinated florets were found among the post pollination treatments. Application of 100 ppm 2,4-D as post pollination treatment showed best result.Haploids and subsequent doubled haploids were produced from Fâ population of three intervarietal crosses of wheat. In total 92 haploid plants were treated with 0.1% colchicine and 86 plants survived. Thirty two fertile doubled haploid plants were obtained, of which 17 were obtained from the cross Sonalika x Kheri. Of the 93.47% plants that survived the treatment, 37.21% were fertile. The cross, Sonalika x Kheri showed best result for the number of fertile DH produced.Six wheat varieties Chyria, Gourab, Kanchan, Rawal, Sonalika and Kheri were crossed with one maize variety Pop Corn to find out the effect of 2,4-D, effect of maize pollens and variation in wheat genotypes for formation of polyembryony. Presence of polyembryos was checked in different situations. Polyembryos were found only in the situation where wheat florets were pollinated with maize pollen followed by application of 2,4-D. Some caryopses contained more than one separated embryo. As many as 5 embryos were found in a single caryopsis. Some caryopses contained polyembryo where more than one embryo were connected with each other. Abnormally shaped polyembryos were also found in some cases where the number of embryos could not be counted due to their firm attachment together. In total 1187 wheat florets were crossed with maize and 16 polyembryos were obtained. The variety Chyria-3 showed highest number of polyembryo (18.18%) over total embryos followed by Kanchan (13.33%) and Gourab (7.5%). Polyembryos were not observed in the varieties of Sonalika and Kheri. Haploid embryos obtained from five genotypes of wheat viz. Gourab, Chyria-3, Sonora-64, Kanchan and Sonalika were cultured on four callus induction media for induction of callus and then on one regeneration medium for regeneration of plants. Callus tissue was initiated from 100% of the haploid embryos cultured. Plantlets were obtained after 2-3 weeks of culture of callus on MS medium. A total of 513 regenerated plants were obtained from 506 haploid embryos cultured. Effect of varieties was found significant for shoot buds forming calli and shoot regenerated calli but not for regeneration frequency. The variety Chyria-3 was the best in percent of shoot buds forming calli and percent of shoots forming calli. Concentration of 2,4-D on callus induction media had significant effect on formation of shoots, shoots per callus, plants per callus and regeneration frequency. Highest percent of shoots regenerated calli, highest number of shoots per callus, plants per callus and regeneration frequency were observed from calli induced from media containing 0.5 ppm of 2,4-D. Variety and media interaction was found significant for the formation of shoot buds, formation of shoots and for regeneration frequency.Second generation of 17 DH lines developed from Fâ generation of the intervarietal cross of wheat Sonalika x Kheri were evaluated along with their parents and two check varieties- Kanchan and Shatabdi. Significant differences were observed among the DH lines, their parents and the check varieties for all the agronomic characters studied. Days to 90% hearing varied widely among the genotypes with a range of 61.67 to 90.67 days. Four DH lines matured earlier than the earlier variety Sonalika. The DH lines differed greatly for plant height ranging from 82.30-111.04 cm. Twelve DH lines, parents and check varieties showed significantly similar number of spikes per plant. A narrow range of variation was observed for biological yield. Four DH lines produced bold size grains that were significantly similar to parent-Sonalika and check varieties. Higher harvest index was obtained from 6 DH lines. The DH lines varied widely for grain yield per plant ranging from 2.90g to 7.78 g. Among the lines 7 lines appeared as better as they had similar yield with the check variety Shatabdi. Four DHs were found better considering their performance for the parameters of biological yield, harvest index and grain yield. Moreover, all the four lines were semidwarf in stature. Therefore, those four DHs were selected as promising for future yield trial.