IRANIAN JOURNAL OF COTTON RESEARCHES
Year:2020 | Volume:7 | Issue:2|Papers Count:7

The Cotton bollworm, Helicoverpa armigera (Lep.; Noctuidae) is one of the most important and most economic pests of cotton. The species is a polyphagous pest and, because of high mobility, high viability under adverse conditions, being multivoltine and resistance to insecticides, it is very difficult to manage. In this study, nutritional effects of chitosan صere studied orally suing different doses of chitosan mixed with an artificial diet. The experiments were carried out under laboratory conditions at six dose rates of 0, 2. 5, 4. 0, 6. 0, 8. 0 and 10. 0 g/kg of artificial diet. Larval mortality, and anti-growth and antifeedant effects were investigated. In this research, mortality of both third and fifth instars did not observe even by two-days feeding from dose rate of 10. 0 g/kg of both chitosan. feeding of third and fifth instars of the Cotton bollworm from different dose rates of chitosan stimulated the growth and feeding of some larvae and inhibited the growth and feeding of some others in each replication. This shows that in dependence on dose rate and larval instar, effects of chitosan on third and fifth instars have been either as growth inhibition or stimulation, and either as feeding inhibition or stimulation. Growth and feeding stimulation of larvae of an insect due to feeding from chitosan is reproted for the first time. This would be led to the better understanding of factors affecting on chitosan efficacy and its effects on different aspects of insect biologies.

In order to and compare a group of genotypes and new cotton hybrids were selected through numerous experiments in term of qualital and quantital characteristics, This project conducted in a randomized complete block design with three replications in two areas Hashemabad (non-stress) and Anbaralum (salinity stress) during two years 2013-2014. 38 genotypes were compared with two commercial cultivars of Golestan and Sepid (as control) were evaluated. The measured traits included: Seed cotton yield (1st and 2nd harvest), yield components (boll weight, boll number, length and number of sympodial branches), plant height and earliness (first to total yield ratio). The results of analysis of variance showed that there were significant differences among the genotypes in the years and locations of experimental for the majority of studied traits at a level of 5% or 1%. The highest yield in non-stress condition was shown for Er26, Tj82, Tj135 and DB24 genotypes. But the ranking of treatments was different under stress conditions so that Tj174, Er34 and Tj135 genotypes produced the highest yield under stress conditions. In terms of tolerance index, Er26, Er29 and Tj82 genotypes were superior to other genotypes. Two components drawn in chart determined 94% of the variations by the GGE biplot software. Finally, Tj135, Er38 and Tj82 were selected and introduced as the best and most genotypes for salinity tolerance.

The establishment of an acceptable population of cotton seedlings is important to obtain high yields. A field experiment was conducted to evaluate the effect of planter type and seed variety on cotton seedling emergence uniformity and irrigated seed cotton yield. The experimental design was a randomized complete block with split-plot arranged in three replications. The seed varieties were in five levels of T2 (V1), Karisma (V2), Lidiya (3), Edisa (V4), B440 (V5) as the main plot and four cotton planter type as the subplot include: grain drill with knife opener and conical press wheel (P1), cultivation combination with cultivator (seed drill) with single disk opener and bar covering device (P2), row crop planter with runner opener and rubber smooth-crown press wheel (P3) and direct drill with double disk opener and double rubber band press wheel (P4). The results showed that variety and planter type had a significant effect on sowing depth, speed of emergence, plant distance, boll number, and seed cotton yield. The P2 treatment compared to P1, P3, and P4, caused sowing depth increasing by 39. 5%, and emergence speed reduction by 52. 1%. The maximum and the minimum number of boll was observed for V3 × P3 and V4 × P2 treatments, respectively. The findings revealed that seed cotton yield influenced by different planters was in the order P3>P4>P1>P2. The results of factor analysis indicated that sowing depth, plant distance, and boll number were identified as the most effective indicators for sowing performance and cotton morphological indexes.

Germplasm is one of the most valuable resources in the field of science and agriculture, which is very important. The main objective of this study was to study the effect of ultrasound conservation in vitro on the growth parameters of cotton seeds (on germination percentage, root length and shoot length). Maintenance technique in liquid nitrogen is one of the methods for preserving seeds and other plant tissues in which plant materials can be stored indefinitely and without loss of fluids. The present experiment was carried out using a completely randomized design with three replications as a factorial on cotton seeds. The first factor was genotype level with two levels (Varamin and Sajedi cultivar) and the second factor was the dewatering time of five levels (20, 40, 60, 80 and 100 minutes) and factor 3 with soluble dewatering (PVS2 and PVS3 and control). The results of analysis of variance showed that the effect of cultivar, treatment time and type of solution on germination percentage, root length and shoot length were significant at 1% probability level (P<0. 01). Regarding the interaction of cultivar during the treatment, both root length and germination percentage were significant (P<0. 05). The effect of cultivar× type of solution also has a significant effect on all traits. The treatment time×type of solution significantly affected only stem length, and the triple effect of genotype during treatment was only significant in terms of germination percentage (P<0. 05). According to these results can be used in protecting cotton seeds germplasm.

Nitrogen (N) is the most important element limiting crop production in cotton cultivation. As N deficiency in plant decreases the seedcotton yield, excessive N availability negatively affects crop production, too. Therefore, N fertilizer management is very important in cotton cropping. Azotobacter and Azospirillum bacteria have been given much attention in agriculture due to non-symbiotic N fixation and improve plant growth and crop production. In order to the studying effect of N and Azotobacter and Azospirillum bacteria on yield and yield components of late-planted cotton cv. Golestan, a field experiment was conducted with four levels of N fertilizer (0, 30, 60 and 90 kg ha-1m from urea as the N source) and four treatments of cotton seed inoculation with the two PGPR bacteria (no inoculation, Azotobacter, Azospirillum and a equal combination of Azotobacter and Azospirillum bacteria). Basis on the results, the effect of N fertilizer was significant on yield and yield components of cotton, whereas the response of yield and yield components of cotton to seed inoculation was not significant. An insignificant interaction effect between the nitrogen and seed inoculation with bacteria was occurred on yield and yield components of cotton, too. According to the experiment's finding, in soil conditions like as present experiment, 75 kg N ha-1 is recommended for double-cropping cotton cv. Golestan, with expected seedcotton yield which is less than 2 tons per hectare.

In order to 36 cotton cultivars and genotypes qualitative morphological characteristics evaluation, in this research, during 2012 to 2013 years in Tehran provinces Agriculture and Natural Resources Research Center at Varamin and Seed and Plant Certification and Registration Institute(SPCRI) at Karaj22 qualitative morphological characteristics studied. Results indicated that, cultivars and genotypes distinct for 11 qualitative morphological characteristics. Based on color of petal cultivars and genotypes divided into 2 distinct yellow and cream petal color groups. All yellow petal color group cultivars, were Sea Island cottons and all cream petal color group cultivars and genotypes were Upland cottons. Among yellow petal color cultivars, for the reason of same level of position of stigma relative to anthers, medium bract dentations at green maturity and strong leaf lower side density of pubescene, Termez 14 cultivar distinct from 2 other cultivars. Cream petal color cultivars and genotypes also based on leaf shape distinct into 2 palmate and lanceolate groups. Lanceolate group cultivars and genotypes were 3 cultivars, Sepid, Okra Leaf-Red and Super okra which among their boll shape in longitudinal section and seed color of fuzz distinct 3 cultivars from each other. Palmate leaf shape cultivars and genotypes group which amounted to31 of evaluated cultivars and genotypes, based on boll shape in longitudinal section divided to 3 main groups. 20 cultivars and genotypes of this group which were cultivars and genotypes with ovate boll shape in longitudinal section also based on 7 characteristics, boll pitting of surface, bract dentations at green maturity.

In order to investigate the effect domestic wastewater of Torbat-Heydarieh on cotton (Gossypium hirsutum L), a field experiment was conducted in a completely randomized design with irrigation water treatments and 3 replications. The treatments were consists of well water (control treatment) T1, treated wastewater T2, 50% wastewater and 50% well water composition T3, alternate irrigation of well water and treated wastewater T4, and 66% wastewater and 33% well water composition T5. The results showed that, the effect of irrigation water treatments was significant on total yield in the first and second year at the P .