The Effect of Growth Regulators on Vegetative and Reproductive Traits of Different Cotton Cultivars in Gorgan Region

In order to investigate the effect of growth regulators on a number of morphological characteristics of cotton cultivars, the present research was conducted as a factorial experiment in a randomized complete block design with 3 replications at Hashemabad Cotton Research Station, Gorgan in 2016 and 2017. Factors included growth regulators treatments with 6 levels (control, benzyl adenine, abscisic acid, salicylic acid, brassinosteroid, and cycocel) and three cotton cultivars of Golestan, Kashmar, and Shayan. Growth regulators affected most traits. Cycocel produced the highest number of bolls per plant (13.4) and abscisic acid reduced the number of bolls by 25% compared to the control. Salicylic acid increased, and abscisic acid and cycocel decreased the distance from the first sympodia to the ground. The highest number of fifth sympodia nodes, respectively, with an average of 7.17, 7.09 and 7.07, was allocated to foliar application with salicylic acid, brasinosteroid and cycocel, and the lowest with 6.07 and 6.13 belonged to abscisic acid and benzyl adenine. Overall, salicylic acid and benzyl adenine were able to increase the internodes length and abscisic acid and cycocel to reduce it. Therefore, with the aim of selecting cultivars with higher boll number, it is possible to use growth regulator of brasinosteroid or cycocel, and Golestan and Shayan cultivars, but to select a higher early maturity percentage, salicylic acid or cycocel, and Kashmar and Shayan cultivars can be used. In general, it is possible to recommend the cycocel growth regulator and Shayan cultivar.