مجله پژوهش های پنبه ایران
سال دهم شماره 2 (پیاپی 20، پاییز و زمستان 1401)

Drought stress poses a significant challenge to crop production globally, including in Iran. Selecting drought-tolerant cultivars is crucial to mitigate adverse environmental conditions. This study aimed to evaluate the drought tolerance of various cotton cultivars using drought tolerance indices to identify the best cultivar adapted to low irrigation stress conditions. In order to investigate and determine the response of 10 cotton varieties to drought stress, an experiment in the form of a statistical design of randomised complete blocks under medium stress conditions and without stress with three replicates was conducted in 2021 and 2022 at the Teaching and Research Farm of Gonbad Kavos University. To evaluate the tolerance and sensitivity of the studied cotton cultivars to drought stress, TOL (tolerance index), MP (mean productivity index), SSI (stress sensitivity index), STI (stress tolerance index), GMP (geometric mean productivity index), YI (yield index), YSI (yield stability index), SDI (drought sensitivity index), K1STI (adjusted stress tolerance index under non-stressed conditions), K2STI (adjusted stress tolerance index under stressed conditions), SSPI (percentage sensitivity index to stress), SNPI (performance index of stress and non-stress conditions) were used. After the analysis of variance and comparison of means, correlation coefficients, principal component analysis and cluster analysis were performed to identify and introduce indicators of drought tolerance. The results of the composite Based on the analysis of variance and the significance of the simple effect and the interaction effects of year, variety and low irrigation, the comparison of the average data in two years was carried out separately, with the highest yield of Vash in the two years 2021 and 2022 under non-stressed (YP) and stressed conditions. Under low irrigation (YS), the Sajdi and Golestan varieties were the highest yielding. The varieties Mai, Shayan, Lodos, Armaghan and Latif achieved above-average yields under both non-stressed and low irrigation conditions. The analysis of the two-year correlation coefficients between the drought stress indices and rice yield under non-stress (YP) and low irrigation (YS) conditions showed the superiority of the STI, MP, GMP and K1STI indices. The results of the analysis by principal components showed that the first two components explained 99.51 and 96.50 per cent of the changes in the first and second year, respectively. The MP, GMP, STI and K2STI indices were the most suitable indices for selecting varieties tolerant under low irrigation stress, as they showed a high correlation with wash yield and more principal components under both conditions. The superior values and cluster analysis of Golestan and Sajdi cultivars were identified as the most tolerant and Sahel and Sepid cultivars as the most sensitive cultivars to low irrigation stress. It seems that production and presentation of varieties with high yield and tolerance to water stress is one of the effective solutions to reduce the harmful effects of water stress.

As a strategic product, cotton has played an important role in creating employment, earning foreign exchange and increasing income in the agricultural sector and related industries, which has always been the focus of government attention. This product plays an important role in agricultural, industrial and commercial job creation, and its importance in agricultural job creation is 2.5 times higher than that of soybeans, 4 times higher than that of corn, 4 times higher than that of rapeseed, and 6 times higher than that of wheat. In recent years, the area under cotton cultivation in the Gonbadkavus district, one of the most important cotton growing areas, has decreased considerably. One of the main reasons for the decline in cotton acreage in Golestan province is economic. In this context, various support and promotion measures have been taken, e.g. seed subsidies, direct payments to producers and guaranteed purchases by the government. On this basis, this study examined the impact of the direct payment policy for cotton producers in the Gonbadkavus district.  In this study, the impact of direct payment policy for cotton producers on cropping pattern in Gonbadkavus district was investigated using positive mathematical planning (PMP) method. The necessary information was collected by completing 93 questionnaires among the farmers of Gonbadkavus district using a random sampling method. After modeling the existing cropping patterns in Gonbadkavus district, the effects of direct payment policies for cotton producers were studied in five scenarios including 2500, 5000, 7500, 10000 and 12500 thousand Iranian rials per hectare.  The results showed that with the different direct payment policy scenarios, the cotton area of 2551 hectares under the current conditions in Gonbad Cavus district increased between 10.58 and 52.91% in the first and fifth scenarios. The total profit also increased between 0.21 and 89 in the different scenarios.  The government's direct payment policy to cotton growers has increased cotton cultivation in Gonbadkavus district, and the total area under cultivation and total profit have not only decreased but also slightly increased. Thus, the implementation of this policy has resulted in the replacement of cotton product with other low profit products and the total profit has not decreased. Therefore, it is suggested that the government take supportive measures to increase cotton cultivation in Golestan province in order to achieve goals such as increasing employment and meeting the demand for raw materials in the province.

Cotton is an important fibre crop worldwide. TheHigh yield is the ultimate goal of a breeding program in cotton. In order to achieve this goal, the production of hybrid cultivars is an important step in increasing production The yield potential of current cotton genotypes can be increased through hybridisation. However, the development of superior hybrids with high yield and better fibre quality requires knowledge of the mode of inheritance and the nature of genetic control of traits. Therefore, genetic analysis plays an essential role in breeding through hybridisation. In this study, the North Carolina II mating design was used to cross 5 maternal and 2 paternal parents to produce 10 intraspecific hybrids. The F1 hybrids were grown together with the parents in the 2021 growing season in a randomized block design at the Karkandeh Research Station of the Cotton Research Institute of Iran. The results of the analysis of trait variance show that there is a significant difference between the genotypes and hybrids studied. Therefore, an estimate of combinability was made to determine the genetic components of the North Carolina II split. The proportion of overall combinability in the traits studied was higher than their private combinability, indicating a greater contribution of additive effects than dominance effects in the genetic control of these traits. For the traits number of reproductive branches, boll weight and strength, the private heritability was 0.75, 0.68 and 0.62, respectively, indicating the involvement of dominance effects in the inheritance of these traits. The role of additive effects in the inheritance of the traits elasticity and uniformity of fibres shows the effect of selection to improve these traits. Among the different hybrids, the highest yield was observed in the cross of Maxa × SKSH 249, which can be attributed to the genetic distance between the two genotypes. Considering the greater contribution of additive effects in the inheritance of performance traits and performance components, using the selection method to improve these traits is the better method. Considering that both additive and dominant effects play a role in the inheritance of fiber quality, it appears that if the aim of the breeder is to improve fiber quality, the use of selection and hybridization methods may be fruitful. These results provide a basis for accelerating the development of high-yielding hybrids in upland cotton.

The onion thrips, Thrips tabaci Lindeman, one of the most important pests of vegetables, ornamentals and leafy crops, is widely distributed worldwide. Therefore, the study of factors contributing to the spread of this insect in agricultural ecosystems is of great importance. Considering the physiological conditions of this pest, wind is considered one of the most important factors for its spread. In this study, we investigated the effects of wind conditions on the spread of T. tabaci in Golestan province in 2021. We selected 48 cotton fields (at the cotyledon stage) in Golestan province and collected data on the relative population density of T. tabaci over a period from 10.03.1399 to 04.04.1399 (three times per week). The relative population density of thrips in each monitoring field (with a minimum size of one hectare) was estimated using the "shaking method" by placing white paper or plastic trays under randomly selected cotton plants, ensuring that they completely covered the lower leaves. We then counted the average number of thrips that fell on the white surface per plant and reported the results per hectare. Wind speed and direction during this period were analyzed using data from eight weather stations and wind rose diagrams were created. The data processing and wind statistics as well as the creation of the wind rose diagrams were carried out using WRPLOT software.  The average population density of T. tabaci in Golestan province during the specified period was 38.5 thrips per plant, with all stages recorded. No statistically significant difference was found between the districts of Golestan province in terms of relative population density of thrips. The percentage of frequency of windlessness (less than 0.54 m/s) was 69.86 to 84.48%. Spatial autocorrelation analysis (Moran's I) was used to identify hotspots (areas with a high probability of occurrence) of T. tabaci. The overall Moran's I values during the monitoring period (I = 0.35, p-value = 0.0174) indicated a random distribution of Thrips tabaci population density data collected in the fields. The map of relative density of T. tabaci in the cotton fields using inverse distance weighting method showed infestation centers in Gorgan, Kordkuy, Bandar Gaz and Aliabad regions.  Based on the results, it is possible to predict the dispersal patterns of onion thrips by obtaining information about the prevailing winds, which in this study came mainly from the west. By predicting the starting points of the infestation, certain control measures, such as the use of sticky traps along the prevailing wind directions, can be recommended to farmers.

Separating the seeds from the cottonseed with a gin has an effect on seed quality and germination. Mechanical damage reduces the economic and biological value of the seeds. The effect of mechanical damage is considered a serious problem in seed production, and reducing this effect leads to an increase in the efficiency of seed utilization. This study was conducted with the aim of reducing the mechanical damage of cotton seed and increasing the efficiency of gin and rotating the saw and moisture content appropriately in two varieties of Hekmat and Golestan cotton seeds.

To increase gin efficiency, the effect of saw rotation in three levels, 300 (S1), 350 (S2) and 400 (S3) rpm, lint moisture content in three levels, 3-5% (M1), 6-8% (M2) and 8-10% (M3) and seed variety in two levels of Hekmat (V1) and Golestan (V2) varieties were studied in a factorial experiment in the form of a completely randomized design with three replicates. The parameters length, width, thickness, geometric mean, sphericity coefficient and bulk density of cotton seed were determined according to the relationship between the physical properties of the seed and the performance of the machine during processing. In addition, the parameters related to the gin, including the extent of mechanical damage to the seed, percentage of ginning and material capacity, were measured. The data were subjected to analysis of variance and the regression equation between the independent variables (experimental treatments) and the dependent variables (measurable parameters) was determined.

An increase in moisture content led to an increase in the geometric mean of the dimensions of the cotton varieties. The increase in mechanical damage to the seed also increased with the increase in moisture content from 6-8% to 8-10%. The main reason for this was the adhesion of the fibers to the cotton seeds and the increase in the time for separating the fibers from the seed. The results showed that increasing the moisture content from 3-5% to 6-8% increased the percentage of ginning operations and the material capacity of the gin in both Hekmat and Golestan varieties; however, as the moisture content increased to 8-10%, the extent of these parameters decreased.

Cotton thrips is one of the most important pests of cotton in the first season and economically in Iran. Nymphs and mature insects of thrips cause deformation of leaves, reduction of green area, loss of terminal bud, dwarfing and multiple branching of plants, reduced growth and consequently lower yield. One way to prevent pest infestation is to treat the seed with insecticides. In this study, the effects of seed treatment with three insecticides were investigated as a factorial experiment in the form of a randomised complete block trial under field conditions.

This project was conducted in the form of a factorial experiment based on a randomised complete block trial with three replications in the provinces of Khorasan-e Razavi and Khorasan-e South. The main factor (A) was tested in 2 stages of delinated and hairy cotton seeds and the secondary factor (B) in 7 stages with the new insecticide thiomethoxam (Cruiser®) at 5 and 7 mm, imidacloprid (Gaucho®) and thiodicarb at 5 and 7 grammes per kilogramme and the control without insecticide. To treat the seeds, the tested insecticides were mixed in 25 ml of water for each kilogramme of seeds, the cotton seeds were placed in the resulting solution and stirred for 10 minutes. After all surfaces of the seeds were covered with the toxic solution, the treated seeds were placed on a paper sheet until they were completely dry, and then cultivation was carried out in the field. After the cotton plants germinated, the evaluations were collected from the first to the fifth week after germination. The data was analysed using SAS software and the mean values were compared using the Duncan multiple range test.

The results showed that the type of seed (bordered or hairy) had no effect on the efficacy of the seed treatment to control the cotton thrips pest, but the insecticide treatments differed significantly from each other in terms of the number of pests. Of the insecticides tested, Gaucho insecticide at a dosage of 7 grams and Cruzer insecticide at a dosage of 7 ml per kilogram of seed had the greatest effect as a seed treatment in preventing damage from first season cotton pests such as thrips.

According to the results of this test, it can be said that Cruiser® insecticides (7 ml per kg of seed) showed the best results as a seed treatment. To prevent feeding and damage by thrips and even other first season sucking pests in the first five weeks of the plant's growing season, this insecticide is recommended for hairy and non-hairy seeds manually or mechanically in seed treatment farms.

Cultivars are the most important factor in achieving optimum quantity and quality of produce, and cotton is one of the most important industrial crops. The aims of introducing new cotton varieties are to increase yield, earliness and resistance to biotic and abiotic stress factors. Despite the improvement and introduction of many new cotton varieties in Iran in recent years, new foreign cotton varieties have also been registered, introduced and marketed in Iran for the first time. Therefore, the cultivation of new foreign cotton varieties that are early maturing, high yielding and have good fiber quality is part of the Ministry of Agriculture's development plan for cotton cultivation. This study was conducted to evaluate and compare the cotton seed yield and its components as well as some fiber quality characteristics of new cotton varieties grown in Golestan province in Anbar Olum region in order to introduce and market these varieties.

 Value of Cultivation and Use (VCU) of six new Turkish cotton varieties, including Carisma, Lydia, PG2018, BA440, Flash and Edesa, compared to Latif and Sahel varieties as control in Fars (Darab) province, evaluated in 2016 and 2017 by determining cotton seed yield and its components (number of bolls per plant and weight of a boll), earliness and fiber quality, including fiber percentage, length, fitness, flexibility, firmness, uniformity, yellowing and brightness, and verticellium wilt tolerance.

Combined analysis of variance over time showed that seed cotton yield, ginning performance, length, fineness, strength, uniformity, and fiber yellowing were significantly different among years of the experiment. In addition, the tested varieties differed significantly in terms of cotton seed yield, boll weight, ginning performance, fibre length, fineness and strength, and the interaction effect of variety x year was significant for fibre elasticity and reflectance. The new foreign variety PG2018 was the earliest maturing variety with a duration of 96.25 days from planting to full boll opening in the first year. The fineness, strength and uniformity of the fibres in the second year were higher than in the first year. The new foreign variety PG2018 had the highest grain yield, and this variety had the lowest fibre length. The fibres of the new foreign varieties Lydia and BA440 had the highest strength. The new foreign variety PG2018 had the highest cotton seed yield in the first year (3705.3 kg/ha). The fibres of the new foreign variety Edesa had the highest elasticity in the first year. The new foreign variety Lydia had the highest fibre reflectance in the first year. In addition, the new foreign varieties BA440 and Lydia were the most tolerant varieties to Verticillium wilt.

Based on the results of this study, among the six new foreign cotton varieties evaluated, the new foreign varieties BA440 and Lydia are recommended as new varieties for cultivation in Golestan province, considering the cotton seed yield and earliness of the new foreign variety PG2018, as well as ginning performance and tolerance to Verticillium wilt. In addition, these varieties should be prioritised as new varieties for cultivation in Golestan province.