| Genetic cooperation in early growth characteristics
of red and amber grained strains of variety Pb C591 M. D. UPADHYA, A. N. PUROHIT and D. K. JOSHI Central Potato Research Institute, Simla (H.P.), India It was shown that the roots of red grained varieties of wheat grow faster and are longer than the amber grained strain of the same variety and the gene producing red colored grain in hexaploid wheat (Triticum aestivum) is associated with faster root growth (JOSHI et al. 1970). Experiments were conducted with a view to finding out, (i) if this differential growth in red and amber grained strains of the variety is restricted to roots or is expressed in coleoptile and (ii) if the factor (s) responsible for faster growth in red strain would also accelerate the growth of amber strain when the two are grown in mixture. The results are presented in this communication. The two strains of Pb C591 having red and amber grains with the same genetic background except for the gene governing red color were used in these studies. The red grained euploid strain was developed from Mono-5A of Pb C591 which had gotton the red grain gene from Chinese Spring (JOSHI et al. 1970). Replicated sets of 40 seeds of each of the strains were sown in petridishes when sown separately, but when the two strains were sown mixed then 20 seeds of each were put in the same petridish, a red seed alternating with amber one. Identical conditions of temperature (20o+ or -1C) and watering in an incubator were provided to all the germinating seeds. Measurements of the main root and coleoptile were taken after 36 and 60 hours of sowing, of the amber and red grains separately when either grown individually or mixed. The mean lengths of main root and coleoptile of these strains are given in Table 1. Statistical analysis of the data were made to test the significance of the differences of means. The results show that when grown separately, the root and coleoptile of red strain were significantly longer than amber strain upto 60 hrs. of growth. These results further confirm the results of JOSHI et al. (1970), indicating the association of the red gene not only with the faster root growth rate but also that of the coleoptile. However, when both the strains were grown in mixture, there was a depression in the growth of root and coleoptile in both the strains at 36 hrs. of germination. But after 60 hrs. of germination the growth of root and coleoptile showed acceleration in both the strains, resulting in longer root and coleoptile as compared to when grown separately. The red strain had longer root and coleoptile length than amber strain. The accelerated growth in mixture after 60 hrs. in comparison to when grown separately indicates a genetic cooperation between the two strains which are genetically identical except for the gene for the red grain color. This phenomenon of genetic cooperation between two strains to mutually accelerate growth demonstrable in petridishes, opens a practicable and easy approach to determine genetic cooperation between isogenic lines, differing only in one character like disease resistance, in the production of successful multiline varieties. Field trials conducted this year have shown a positive increase in yield of mixtures of two strains over their pure stands, confirming the genetic cooperation tests made in petridish (UPADHYA and BANSAL, in preparation). Literature cited JOSHI, B. C., D. SINGH and M. D. UPADHYA. 1970. Red gene associated with faster growth of roots in hexaploid wheat. W. I. S. 31: 8-9. (Received July 1, 1971) |