Evaluation of Glycine Betaine effects on some agronomic traits of cotton

To evaluate the effects of Glycine Betaine (GB) on yield and seed quality of some cotton (Gossypium hirsutum L.) cultivars in response to drought stress, a field experiment was conducted in northern part of Iran, Gorgan. The experiment was a factorial on the basis of a randomized complete block design with four replications. Field research survey consisted of two factors; GB concentration and cotton cultivars. Glycine Betaine was applied to filed-grown cotton at three rates: 0 kg/ha foliar application of GB at the first flowering + application at one and two weeks later, 3 kg/ha foliar application of GB at the first flowering + application at one and two weeks later (two times GB application) and 6 kg/ha foliar application of GB at the first flowering + application at one, two, three and four weeks later (four times GB application). Four cotton cultivars were selected based on their proportional susceptibility to drought stress including Tabladilla and Nazili, considered as drought tolerant, and Varamin and Sahel, considered as drought sensitive cultivars. The results showed that spraying with GB at different levels (3 and 6 Kg/ha) enhanced cotton yield, boll numbers, sympodia branch numbers, early maturity, plant height, final node on main stem, boll retention at 2nd position and boll abortion, seed bulk density, but had no significant effect on monopodia branch numbers. This research could ultimately result in higher yield production and improved tolerance to water deficit condition with applying following treatments: Tabladilla and Nazili with 3 kg/ha foliar application of GB at the first flowering + application at one and two weeks later for tolerant cultivars and Varamin and Sahel with 6 kg/ha foliar application of GB at the first flowering + application at one, two, three and four weeks after first flower.