IRANIAN JOURNAL OF COTTON RESEARCHES
Year:2015 | Volume:3 | Issue:1 |Papers Count:8

Vascular wilt fungus, Verticillium dahliae, and root knot nematode, Meloidogyne incognita, are the most common and destructive pathogen factors in cotton. In order to study interactions between these two factors, their interaction effect on 4 cotton cultivars (Sahel, N200, Mehr and Varamin) was done in a completely randomized block design in 4 iterctions and 6 treatments in a greenhouse. Treatments including, control, just fungus, just nematode with concentration of 2300, just nematode with concentration of 7000, both fungus and nematode with concentration of 2300 and both fungus and nematode with concentration of 7000.12´104 Microsclerote for each fungus treatment and 7000 and 2300 nematode eggs and second stage juvenile for the nematode treatments respectively (depending on the desired treatment) were inoculated to 60 days old cotton seedling.Meloidogyne incognita nematode was isolated from the host plant and then its species and race were determined and at last it was reproduced by inoculation to tomato transplants. After that theVerticillium dahliae fungus was isolated from infected cotton plants and after cultivation and identification steps, it was transfered to the Tajan wheat seed cultivar (three times been autoclaved) for reproducing.The results of this review after 2 months showed that the interactions betweenVerticillium dahliae fungus and Meloidogyne incognita nematode in cotton was resonator. As a combination of fungus and nematode simultaneously leads to a significant increase (P=%1) in the wiltdejection. With increment in nematode concentration, root rot, the number of nodes and egg mass increased and shoot and root length, fresh and dry weight decreased vice versa.

The aim of this study was determination of cotton production function, investigation of economical and social parameters on cotton yield, profitability of cotton production and calculation of production elasticity in Gorgan during 2014 year. It had been got necessary information by interviewing and completing questionnaire and it had been selected 50 cotton farmers in that region for reaching to above target by using randomized sampling. The most suitable model after many considerations and various tests in order to determinate cotton production function was cobb–douglas production function, in which study the effect of labor factors, capital, use the pesticides and chemical fertilizer and other factors is being stated and computed by OLS method and Eviews software. The rational rate of inputs consumption was determined after calculation of production function and inputs elasticity. The result showed that the production elasticity values for land, fertilizers, seeds and pesticide was positive while its value for labor inputs were negative. In other words, the farmer׳s used inputs such as land, chemical fertilizer, seed and pesticide in production economic zone, but labor inputs has been produced in third region and more than optimal level. Furthermore, the sum of elasticity value of inputs was equal 1 which indicated positive efficiency than to scale in cotton production of Gorgan.

In order to evaluate the effect of drought stress onyield and yield components of cotton and selection ofthe best cultivars, an experiment was conducted as complete randomized block design (RCBD) with three replications on 14 cotton cultivars at Agricultural Research farm of Technical and Vocational Training center, Nehbandan, Khorasanjonobi under normal irrigation and drought stress in 2012. The results of variance analysis showed that there was significant difference among cultivars for all traits under stress and non-stress conditions. The effects of drought stress was significant on day number to flowering, plant height, number of sympodial branches, cotton yield, number of boll per plant and lint percentage.The assessment of simple correlation coefficient showed that the yield was positively and significantly correlated number of bolls per plant, number of sympodial branch, plant height and lint percentage. The traits of plant height, number of sympodial branches, day number to flowering, lint percentage and number of bolls per plant can be considered as the best indices for yield improving.In analysis of biplots, traits of numbers of sympodial branches and bolls per plant were as distinguishing traits and cotton yield was as traits representative. Also cultivars of Varamin, Bakhtegan, Mehr and Sahel had more stable yield. Varamin cultivar was similar to ideal cultivar.

Study of production region, ginning and delinting effects on cotton seed germination and vigor, in Sahel variety was conducted as factorial based on completely randomized design by 4 replications. Treatments were included ginning of cottonseed in west and east area of Golestan by hand, roller, 8 and 16 saw gin and also delinting by Solphoric acid and no delinting. By standard germination test, numbers of normal seedlings, mean germination time, seedling length and dry weight were determined and electrical conductivity of seeds was measured. The interaction effect of Seed production region× ginning methods×delinting was significant on studied traits. The highest and lowest of normal seedlings numbers were related to Seeds of east region ginned by roller, no delinted seeds and 16 saw gin, delinted seeds, respectively. East seeds of Golestan which ginned by 16 saw and no delinting and west of Golestan, ginned by roller gin and delinting had the highest and lowest mean germination time, respectively. Delinted and no delinted seeds in east and west of Golestan province and ginned by roller, 8 and 16 saw gin had the highest and lowest of seedling length, repectively. Seeds of east province which ginned by hand, roller gin and delinted and no delinted seeds which ginned by 8 and 16 saw gin had the highest and the lowest seedling dry weight. The lowest and the highest of electro conductivity were related to ginned seeds of west region by 8 saw gin, no delinting and ginned by hand and delinting, respectively. Based on results, Sahel cultivar seed ginning, especially produced in west of province by roller gin could be recommended for reduction of seed coat mechanical injury and destructive effects of delinting by acid on germination and seed vigor.

Due to water deficit in Golestan, it is necessary to optimize use of water which means to find relation between water use and yield. For this reason, this experiment was conducted by sprinkler irrigation as line source. Six irrigation treatments as I1, I2, I3, I4, I5 and I6 is assumed in two hand of sprinkler line because of sprinkler water triangular distribution, so that I1 and I6 treatments received the highest and the lowest water, respectively and I2 treatment received as water requirement as.Three cotton cultivars of Sahel, Sepid and 818–312 were planted by 20 × 80 centimeter. Experimental design was strip split plot with three replications. The results showed that the highest yield was I3 treatment that with I4, I5 and I6 treatments in the first year and all treatments in the second year had significant difference. Sepid cultivar yield was 17.9 % higher than two cultivars in the first year and 15 % higher than Sahel cultivar in the second year. Difference between three cultivars on view of earliness was not significant and on view of boll weight in the first year was not significant but in the second years was significant. The highest boll weight belonged to I3 Treatment and also I6 Treatment was the highest earliness. Sahel cultivar during two years had the lowest micronairy. Treatment of I3, received on view of water use received 30% less water than water requirement.Ultimately, on view of yield, quality properties and less water use, the best irrigation treatment and cultivar were I3 treatment and Sepid cultivar.

Tolerant cultivars are the important components of integrated pest management. In this study, 20 different cotton genotypes were evaluated during 2 years using RCBD in Gorgan in order to compare genotypes for frequency of whitefly (Bemisia tabaci Genn.) eggs, nymphs and adult population, and also to determine the relationship between effective morphological characteristics of cotton and pest accumulation.Results showed significant differences among genotypes for majority of morphological characteristics andB.tabaci population. Deformed Leaf, Red Leaf Okra, Broad Red Leaf, Siokra and Frigo Bracteeles genotypes had the least nymph's density, but Termez, Alyaf Rangi and Pak showed the highest density of nymphs. Regarding adult whitefly population, Deformed Leaf genotype had the least pest density, and also Siokra, Red Leaf Okra, Super Okra and Broad Red Leaf genotypes had the low pollution, but Termez, Alyaf Rangi, Pak and Smooth Leaf had the highest density of adult whiteflies.Results suggested that leaf shape and area could be supposed as two most important factors affecting pest population density, as the more reducing leaf area and more deep evolve its dents, the less pest population density. In addition, the low pest population on red leaf genotypes suggested non-preference or escape mechanism. There was positive correlation between density and height of pubescences and whitefly population density, as the more and higher pubescences, the more pest population. In addition, there was positive correlation between leaf area, plant height and sympodia number with whitefly population density, but there was negative correlation between the traits of leaf color, flower color and shape of the flower bracts with density of this pest.Overall, results showed that the characteristics of okra leaf shape, low leaf area, red plants, low density of pubescences and high density of glands could be effective in reducing the whitefly population density.

Technological development in agriculture as the main source of increased productivity requires sustained investment in agricultural extension and research.However, in recent decades, investment in agricultural research in developing countries has reduced and the agricultural research systems of public sector (government) in these countries, including Iran, have been faced with the challenge of funding research needs. In such circumstances, the funding of this type of research requires to provide documentary evidence of the interest of them to economic policymakers. Without revealed and compelling documentation of benefits, agricultural research will not earn sustainable financial support.Therefore, this study estimated the potential benefits of cotton breeding research under its risk in agro-climatic zones of Iran that its results could set economic policymaking to persuade and convince for worthy support of cotton research. In order to conduct of this research, economic surplus method was used that can prepare effective outputs to derive the benefits of the research. Based on the findings, cotton breeding research in all studied zones, despite the uncertainty and the risk of their benefits, had acceptable economic returns.So that, its expected average of internal rate of return, despite the risk and uncertainty of research and agricultural activities, was in the range of 26 to 40%. Therefore application of technology (improved seed) derived from them, can increase cotton production and supply and play fundamental role in cotton production and consumers benefits.This evidence emphasize on necessary funding of agricultural research and its risk management.

Yield increasing and also the introduction of new varieties of cotton is one of the main goals of researchers. The important goal of this research was recognition of superior varieties in terms of yield. New and cultivated cotton genotypes including new varieties B557, T3, T2, SB35 and commercial cultivars like Moghan, Golestan and Sahel were evaluated in a randomized complete block design in Karkandeh Cotton Research Station. The results showed that T2 variety with 2160 kg/ha had the highest yield and SB35 variety with 1806 kg/ha had the lowest yield.Variety of B-557 with 75.8 % and varieties of T2 and T3 with 73.5 and 74.6 % were the earliest genotypes, respectively. Late maturity among varieties belonged to Armaghan and SB35 varieties with 53.8 and 55.7 %, respectively. The highest and lowest bolls weight were related to Golestan cultivar with 183.2g and T3 genotype with 153.8g, respectively