Analysis On The Effect Of Genetic Improvement In Maize In Sichuan Province At The Beginning Of The 21st Century

Sichuan Province is a principal yield site for maize. This article studied on the approved maize varieties at the beginning of the 21st Century (2001-2015, and the varieties in 2015 are first-approved) in Sichuan Province, based on the data of the regional test. We analyze the effects of genetic improvement comprehensively this will contribute for the present situation and future development direction of Maize Breeding in Sichuan Province. Therefore, this article mainly analyzes the quantity and distribution of approved maize varieties, the distribution of first-breeding units, the yield and yield characters, the effect of genetic improvement on quality and resistance and so on. At the same time, we give advices on the work about genetic improvement on new maize varieties in Sichuan Province.1.During 2001-2015,the work of maize breeding in Sichuan province is developing quickly, and this has made an important contribution for maize yield and the development of seed industry. During this period, the quantity of approved maize varieties by Sichuan province is 301,189 of this varieties belong to the even & hill group,75 belong to the mountain group and 37 are for special uses; 259 of this varieties are bred by the breeders of Sichuan province and 42 of this varieties are bred by the breeders of the other provinces; The varieties bred by scientific units go over the varieties bred by enterprises, but the quantity of the approved varieties bred by enterprises almost equal the quantity of the approved varieties bred by scientific units in the 12th Five-Year Period. There are 123 first-breeding units totally, 90 of them are in Sichuan province,33 of them are units from the other provinces.In the first-breeding units, the scientific units is more than enterprises, but the enterprises go over the enterprises in the 12th Five-Year Period. So, the units in Sichuan province especially the scientific units are the main units, but the enterprises has become the largest main units in commercialized breeding gradually during 12th Five-Year Period.2. The promote of yield is primary goal for genetic improvement, The average yield of the even&hill group, mountain group of variety in Sichuan respectively are 501.7kg/667m2 mu,544.2 kg/667m2,the level of yield is higher than others. The breakthrough progress for the improvement of yield of the even&hill group has been made during the 11th Five-Year Period. The quantity of high yield has increased significantly during the 12th Five-Year Period, which reflects the ability to breeding high yield varieties has been improving. The varieties of mountain group for improving the yield is breakthrough continuously, in this years, both the average yield of approved varieties and the yield which is greater than 600kg/667m2 has been clear increasing.3. The correlation and path analysis of maize yield and its traits shows that as for the variety of even & hill group, thousand seed weight has always produced a positive role in increasing the yield, and the ear length is the main limiting factor for this group; while for the variety of mountain group, ear row acts as the similar role like the thousand seed weight mentioned above, and ear length serves as its limiting factor, which demonstrates that in the following maize breeding work. We should continue to assure the contribution of thousand seed weight in the areas of even & hill group and mountain group, and we should also place our emphasis on strengthening the genetic improvement of ear length, and we should also continue to assure the contribution of ear row in the areas of mountain group at the same time.4. Based on the analysis of quality improvement of the approved varieties by Sichuan province from the year 2001 to 2015, the average value of unit weight, crude protein, crude fat, crude starch and lysine are 741g/L,10%t,4.6%,73.7%t and 0.31% respectively. Achieving the primary standard for feeding, nutritional, processing and commercial quality are 87.96%,1.61%,37.15%,76.39%. Compared with the approved varieties by the other province in the same period and by Sichuan province at the end of the 20th century(1981-2000), the nutritional quality is higher, however it progresses slowly. Besides, the processing quality is higher and stable, the feeding quality and commercial quality are higher but progresse slowly. When it comes to breeding new varieties and the work of quality improvement, it still remains as a high priority to improve the content of unit weight in the following days.5.Based on the analysis of resistance improvement of approved varieties by Sichuan province from 2001 to 2015, the maize varieties which can resist leaf blight, stem rot, dwarf mosaic, helminthosporium maydis nish et miy, banded sclerotial blight, ear rot and ostrinia nubilalis account of 80%,71%,90%,77%,61%,67% and 74%respectively in the total number of identified, that is to say, the percentages are all above 60%, except the maize which can resist head smut only accounts of 36%. These can reflect that most of the ability of resistance are strong. Meanwile the ability of resistance leaf blight, is stronger than that in the end of 20 century, and the ability of resistance banded sclerotial blight and head smut relatively poor, and head smut is also weaker than that in Sichuan from 1991 to 1999. Taken together, the difficulties of resistance breeding are still banded sclerotial blight and head smut in a certain period and at the same time, the maize’s ability of resistance helminthosporium maydis nish et miy should be improved.Above all, the scientific and research input and research force of maize breeding work in Sichuan province has reached a new level at the very beginning of 21st century. We have achieved obvious results in terms of maize yield, resistance as well as genetic improvement of its quality. In the following days, we should continue to assure the advantageous contribution of thousand seed weight and ear row on increasing the yield. Meanwhile, it remains as our priority to strengthen the improvement and selection of thousand seed weight, and try to reduce its restriction to the output. Based on the market and real yield situation, we should concentrate on the simultaneous improvement of quality and resistance, adding our effect on researching and utilizing the maize for special use. We should also standardize the breeding team so as to advance to a The modern crop seed industry system which featured on "breeding, reyield, pushing"integration.