Germination and early growth response of guar cultivars to low temperatures

Abstract

Demand for galactomannan gum from guar, commonly known as guar gum, has exponentially increased in the last few decades due to increased use in oil and natural gas, food, cosmetics, paper and other industries. The United States of America is the major importer of the guar gum in the world, which is mainly grown in deserts of India and Pakistan. There is need to increase guar production in non-traditional areas to ensure steady supply and reduce market volatility. Expanding guar acreage into cooler regions of the southern High Plains or in similar agroclimatic regions of the world is an attractive option. Therefore, a study was conducted in incubators to assess genetic variations among currently available guar cultivars for germination and early growth under cooler temperature ranges. Six temperatures (13, 16, 19, 22, 25, and 28 °C) and six guar cultivars (Kinman, Lewis, Matador, Monument, Santa Cruz and Judd 69) were used. Guar cultivars exhibited significant variations for germination percentage, mean germination time and seed vigor index under lower temperatures, which narrowed as the temperature increased closer to optimum. Mean seed germination percentage of cultivars reached maximum at 22 °C. However, speed of germination and seed vigor indices, which are indicators of quick and uniform establishment of guar in the field, continued to increase till 28 °C. Kinman, which was the most promising guar cultivar under cooler temperature, reached maximum germination percent at 16 °C and had the lowest germination time and highest seed vigor index among cultivars below 16 °C. In contrast, Matador reached maximum germination at 26 °C. Germination and early seedling traits indicate that it is better to plant guar in warm soils and if needed to plant in cooler conditions, cultivars like Kinman should be used.