| Short season upland cotton plays an important role in the cultivation reform in China, there are three ecotypes in cotton growing region: the first is the north extra early ecotype, which fit for North (extra early) and North West Inner Land, such as Liaomian's and Xiluzao's series varieties; the next is Yellow River Valley ecotype, such as CRI's and Yumian's catena varieties, and the third is Yangtze River Valley e-cotype, which adapt intercropping and interplanting cotton with wheat or rape.The objectives of this study were (i) to evaluate the genetic improvement contribution in the past fifty years, (ii) to detect the genetic diversity among the short -season upland cotton varieties, (iii) to understand the inheritance of earliness and the main economic characters of the short season upland cotton, (iv) to illustrate the biochemical genetic mechanism in the earliness - but-not-decrepitude varieties.We evaluated 24 obsolete short season upland cotton varieties and 4 current commercial varieties for lint yield, other main agronomic characters, earliness, and fiber properties over 2 -years period, 2001 to 2002, at 5 - points to determine what genetic improvements the new varieties had over come the older ones. The mean of current commercial varieties breeding value of lint yield approximately 396. Okg/ha more than the 1950's varieties, with the speed of 7. 92 kg/ha each year. These data indicated that varieties exhibiting increased yield potential had high lint percentage, bigger lint index, smaller seed index, and higher HVICC fiber strength. Increases in the lint percentage have played a major role in yield increasing. Fiber properties of varieties currently grown were better than those of some old ones, but inferior to those of others. Advance in fiber properties have not been as rapid as advance in lint yield. At the same time, the problem of resistance to Fususium wilt has been overcome, and the resistance to Verticillum wilt was improving. The earliness had been shorted two and half days, which caused by the reproductive stage becoming shorter in 1990's.The result of the genetic diversity analysis based DNA molecular markers technologies (RAPDs and SSRs) indicated that polymorphism among the short -season upland cotton cultivars was very poor. Twenty - nine varieties were screened with nine hundred random 10 -mer primers, which genetic relations were more distant in pedigree. Only 122 primes (13. 6%) amplified polymorphic fragments. In 302 pairs SSR primers, only 41 primers (13. 6%) get the polymorphism; the genealogical classification of more two hundred varieties (or lines) also proved that, the King was the main earliness gene pool of the short-season upland cotton genetic improvement in China in the past fifty years.A partial -diallel genetic design consisting 10 pure lines and their 5 (Pi Pj) F1 and 5 (Pj Pi) F1 , and 10 F2 populations were grown at the same field in Chinese Cotton Research Institute in 2001 and 2002. The experimental design was a randomized complete - block with three replications. Standard agricultural practices for Yellow River Valley region were adopted, and the 30 treatments were grown in three- row plots, which was 2. 1m by 8. 5m (17. 85m2), in the two years. The genetic variance components were estimated by Minimum Norm Quadratic Unbiased Estimation (1) with GENEVAR1R. EXE, and Jackknifing over block was conducted for estimating standard error, and Linear Unbiased Prediction (LUP) method, for predicting genetic effects, including additive, dominance, additive additive and its interaction with environments, with ADAA model (or additive, dominance, cytoplasmic- maternal effects, and its interactions with environments, with ADM model). The cytoplasmic and maternal effects plays an important role on Anti - oxidant enzymes (such as CAT, POD, and SOD) activity, IAA and ABA contents, and chlorophyll a/ b when analysis by ADM model; With the ADAA model, the additive additive epista-sis effects were also detected on the same biochemical index, such as SOD a...
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