The Heterosis Of Interspecific Or Intervarietal Hybrid And Its Hormonal Basis In Wheat(Triticum Aestivum L.)

As one of the major crops in China, wheat plays an important role in the food supply of the populated country and its trade market. Utilization of heterosis is an important and useful way to increase crops yield and improve quality. Limited heterosis is one of the major problem in the use of hybrid wheat in the field. In order to broaden genetic basis of its parents and improve its heterosis degree, 2 speices in Genus Triticum were used to cross with common wheat and planted in the field for two years. The yield and its components of the interspecific hybrid were studied and compared with that of intervarietal hybrid, the quality parameters ware measured in the interspecific hybrid, the fertile spike and 1000-grain weight formation were also studied in concern with their endogenous hormone level of the interspecific or intervarietal hybrid, the results were showed as follows: 1. The average heterosis of the grain yield per plant is 75.79%, 57.67% and 12.55% in the hybrids of the common wheat with spelt wheat, club wheat and itself respectively. the heterosis degree of the interspecific hybrid was greater than that of intervarietal hybrid. 2. The heterosis of spike number per plant and grain number of main spike were stable in the intervarietal crosses between years , and so were the grain number of main spike in the crosses of common wheat with club wheat, and were the 1000-grain weight in the crosses of common wheat with spelt wheat. 3. The SCA effect was important in the heterosis of the spike number per plant of the intervarietal hybrid, the SCA and GCA were both important in the heterosis of the grain number of main spike of the intervarietal hybrid; the SCA effect played an major role in the heterosis of the spike number per plant of the interspecific crosses of the common wheat and club wheat, the SCA effect played an major role in the heterosis of the 1000-grain weight of the interspecific crosses of the common wheat and spelt wheat. 4. In all kind of hybrids, the heterosis of spike number per plant and grain yield per spike were the first level contributors to the heterosis of grain yield per plant, the heterosis of grain number and the 1000-grain weight were the second level contributors to the the heterosis of grain yield per plant . 5. The grain protein and wet gluten content of the hybrids between common wheat and spelt wheat were significant higher than that of female parents common wheat in the year 2001 but not significant higher in the year 2000, The grain protein and wet gluten content of the hybrids between common wheat and club wheat were significant lower than that of female parents common wheat in the year 2000 but were not significant higher in the year 2001. The grain protein and wet gluten content were quite variable between the two years. 6. The heterosis of grain hardness of interspecific hybrid between common wheat and spelt wheat or club wheat were usually negative except that of hybrid between common wheat variety Nongda 3226 and spelt wheat or club wheat. 7. The average heterosis over parents of Sedimentation value of the interspecific hybrid were 7.2% in all crosses, but the average heterosis were 19.9% in the crosses that were better to their parents. The Sedimentation value were relatively stable between the two years. The hybrid that had a high sedimentation value also had a good farinograph parameters. 8. There were high level genetic diversity in the parents of the interspecific hybrid, and the HMW-GS were co-expressed in F1 and segregated in F2, this supplied a material base for good quality. 9. Just the CTK content, the ABA content in its tiller node were most significantly related and most significantly negatively related to the tiller number of intervarietal hybrid respectively, but beside the CTK content, the ABA content in its tiller node were significantly related and significantly negatively related to the tiller number respectively, the IAA content were also most significantly related to the tiller number of interspecific hybrid, this may be the reason why the interspecific hybrid had a high fertile spike heterosis. 10. The 1000-grain weight heterosis was mainly due to the grain fresh weight heterosis at 12 DPA and 22 DPA that the intervarietal hybrid had, and also due to its promotion of 2 kinds of hormone IAA and CTK 12 DPA, the IAA function extended to 22 DPA. 11.The outstanding 1000-grain weigh heterosis of interspecific hybrid was highly related to the fresh weight heterosis of grain at 12 DPA, three kinds of hormones IAA, CTK and GA cooperated to promote the grain growth at this time to get enough fresh weight, the function of IAA lasted to 20 DPA, there were some degree heterosis of GA content in the grain at 12 DPA. 12. The high content of GA were found to be paralleled to the increasing expression of some gene, which was identity to the NG28 PROTEIN gene sequence in RIKEN or the gene of ATP synthase F1, gamma subunit.