Some quantitative and qualitative traits as well as Verticillium wilt (Verticillum dahlia Kleb). tolerance in 9 cotton (Gossypiumhirsutum L.) hybrids and cultivars were evaluated in a field experiment at Karkandeh (Kordkouy) and Hashem abad cotton research stations in 1996-1997. The experiment was arranged in a completely randomized block design with four replications. Different traits as yield, earliness, disease tolerance, yield components (average of boll weight and boll number) and lint properties (lint percentage, lint length, miconair, and pressley index) were investigated. To compare tolerance of cotton entries to Verticillium wilt, disease index (DI) was calculated by multiplication of disease severity (DS) by percent of infected plants. The results of combined variance analysis indicated that, there were significant differences (P<0.01) between cotton entries for all traits. Based on combined means comparison results showed that SIOKRA 324 with the best Guantitative and qualitative characters and tolerance to Verticillium wilt is a releasable variety for Golestan province.

Delay in sowing, and increasing plant density in order to compensate yield lose resulted from delayed sowings, induce some changes in morphological characteristics of cotton such as main stem height, main stem node number, and monopodial and sympodial branche number and length. Thus, in order to investigate the effects of planting dates and plant density on morphological characteristics of cotton, an experiment was conducted using SIOKRA cultivar in 2002 at Cotton Research Station of -Karkandeh, Kordkoy. The experiment was carried out as a split - split plot in a randomized complete block design with four replications. Three planting dates (May 15, May 31 and June 22) considered as main plots, and two row spacings (60 and 80 centimeters) and three plant distances (10, 20 and 30 centimeters) considered as sub- and sub- sub- plots, respectively. The results showed that delaying in sowing date decreased monopodial branche number and plant height, and increased length of the highest monopodial branche, the number of sympodial branche and main stem node. However, the influence of sowing date on the length of sympodial branches was not significant. In all three planting dates, an increase in plant density accompanied with decrease in monopodial and sympodial branche number per plant, length of the highest monopodial branche, sympodial branche length, and main stem node number, whereas main stem height increased to some extent. Among morphological characteristics of cotton, main stem node number (in normal planting date), and length of the highest monopodial branche (in other planting dates), showed the most sensivity to increasing in plant density.

In order to study combining ability and gene action for quantitative traits in intra and interspecific hybrids, three genotypes of G.hirsutum with three genotypes of G.barbadense were intercrossed in a half-diallel pattern. Fifteen hybrids with six parents (21 genotypes) were studied in a randomized complete block design (RCBD) with three replications at Gorgan (Karkandeh) Cotton Research Station. Some quantitative and morphological traits (yield, boil weight, boil number, plant height, monopod and sympod length, monopod and sympod number) were measured and recorded in hybrids and parents. Results showed significant differences among genotypes for all traits, except for sympod number. Based on mean yield SIOKRA 324xTabladila (intraspecific hybrid) and Termez14xSIOKRA324 (interspecific hybrid) were superior, in comparison to the other hybrids. Combining ability analysis showed that additive and non-additive variances were effective on cotton yield, boil number, boil weight, plant height, and sympod length, however, additive gene action may be important for the monopod number and monopod length. The SIOKRA324 (G.hirsutum) and Termez 14(G.barbadense) were identified as best parents for GCA. Siokr 324× Tabladila (intraspecific hybrid) and Termez14×Tabladila (interspecific hybrid) had best specific combining ability. Estimates of the genetic parameters according to Hyman and Jinks method supported the results. Average degree of dominance at each locus and graphical analysis indicated partial dominance for boil weight and monopod length, and over dominance effects for other traits. Dominant genes had positive and increasing effects on the yield, boil number, plant height and sympod length.      

One of the important factors in crop management decisions in order to obtain high yield with optimum quality is plant density for different planting dates. In order to investigate the effects of delayed planting dates and plant density on yield and yield components in cotton (cv. SIOKRA), an experiment was conducted in 2002 at Cotton Research Station of Karkandeh-Kordkoy. The experiment was a split-split plot in randomized complete Blok design with four replications. Three planting dates (May 15, May 31 and June 22) were allocated to main plotes, two row spacing of 60 and 80 centimeter and three plant distance of 10, 20 and 30 centimeter were levels of second and third factors, respectively. Results showed that with delay in planting date, yield and number of boll per square meter decreased but boll weight and number of seed per boll increased. Lower number of boll per square meter, more shedding of productive organs and low boll maintenance were the main reasons of yield reduction by delayed planting dates. The first plating date compared with the second and the third planting dates produced 25% and 58% more yield, respectively. There was a positive correlation between boll number per square meter and yield. Optimum plant density (plant density that had the greatest yield) was 13.8 plants per square meter for normal sowing date and 9 plants per square meter for the latest sowing date. For the second sowing date there was no response to planting date.

Priming is one of the seed enhancement methods that might be resulted in increased seed performance (germination and emergence). The objective of this research was to evaluate effect of priming on seed emergence and yield under wide ranges sowing dates in cotton. Treatments were combinations of 6 sowing dates and 2 seed treatments (control and primed seeds). Hydropriming method was used; seeds of SIOKRA 324 were moistened in water for 16 h at 25oC. Results indicated that priming affects seed emergence components. Primed seeds had faster and more uniform emergence at all sowing dates. Priming also affected germination response to temperature; primed seeds “emerged” at lower base temperature. Base temperature was 15.4oC for control seeds, but was 13.5oC for primed seeds. Primed seeds had high yield than unprimed seeds (control) at all the sowing dates.