The Evolvement Of Cotton Cultivars In China With Resistance To Fusarium Wilt And Verticillium Wilt Bred After The Establishment Of PRC

Fusarium wilt and Verticillium wilt of cotton are still the serious problem of cotton production in China. It has been confirmed that by using resistant cultivars these two kinds of cotton wilts could be successfully controlled.The experiment materials are 110 cotton cultivars with resistance to Fusarium wilt and Verticillium wilt bred from 1950's to 1990's,including 2 cultivars of 1950's; 15 cultivars of 1960's; 23 cultivars of 1970's; 40 cultivars of 1980's; 30 cultivars of 1990's.1. Since the establishment of PRC, obvious progresses had been made in cotton Fusarium wilt resistant breeding. The means of pathogenic index resist Fusarium wilt of 1990's descended 20.1 percent compared with 1950's. But the mean of pathogenic index resist Verticillium wilt showed a increasing trend from 1980's to 1990's. The Verticillium wilt resistant breeding developed slowly. The process of the 110 cultivars resisting Verticillium wilt can be divided into 3 modes, and the cultivars belong to the third mode are superior in yield. The cultivars that have high resistant to Fusarium wilt and resistant to Verticillium wilt accounted for 11 percent of the total.2. Cotton yield showed increasing trend except the varieties released in 1970's. The mean yield of 1990's varieties had increased by 18.6 percent compared with 1950's. The mean of boll number per plant of 1990's is on the low side, but no significant variation in different times. Lint percentage showed descending trend from 1950's to 1970's and increasing trend from 1980's to 1990's. The yield increase was caused by boll number per plant firstly and by boll weight secondly.3. The evolvement trends of 2.5% span length, fiber uniformity, fiber strength, elongation are nearly similar, descending from 1950's to 1970's and increasing from 1980's to 1990's. The macronaire values of the 110 cultivars are generally higher compared with the international standard. The fiber quality of 1990's is superior.are generally higher compared with the international standard. The fiber quality of 1990's is superior.4. The evolvement trends of whole growing period and maturity are similar, becoming short from 1960's to 1990's.5. The evolvement trends of plant height, first fruit branch node, distance between the first fruit branch and cotyledon are also similar, descending from 1960's to 1970's. There are a strong correlation between the 3 traits and the whole growing period. The number of leaves and fruit branches are also show a descending trend, but no significant variation in different times.6. The negative correlation between the yield and fiber quality had been broken out gradually by the replacing of cultivars. There are strong correlation between the yield and plant height, first fruit branch node, distance between the first fruit branch and cotyledon by working on the boll number per plant.