Growth and Seed Yield Performance of Promising Guar Genotypes Under Different Planting Dates in Desert Southwest.

Guar or cluster bean (Cyamopsis tetragonoloba L.) is an alternative pulse crop that has potential to grow under limited water conditions in desert southwest. Guar can tolerate high temperatures and dry conditions prevailing in arid and semi-arid climates such as in New Mexico. Guar has multiple uses. It can be used as protein-rich high quality forage for animals. Fresh pods are used to cook as vegetables, while guar gum, a by-product of seed, is used in food, pharmaceuticals, cosmetic, and oil industries. Use of guar gum by oil industries in hydraulic fracturing has made USA biggest importer and consumer of guar. Study was conducted at two locations (Las Cruces and Clovis) in 2014 to test the growth and yield performance of promising guar genotypes under different planting dates. Eight genotypes were tested under four different planting dates (April 25, May 15, June 16 and July 1) in Las Cruces, while four  genotypes were tested under 3 different planting dates (June 18, July 7, and July 22) in Clovis. June planted guar produced comparatively higher photosynthetic rate, above ground biomass, and seed yield at both locations. Genotypes differed significantly with regard to seed yield at Las Cruces, but no significant difference was observed between genotypes at Clovis. Planting date and genotypes had a significant interaction for seed yield at Las Cruces. Delayed planting had a negative effect on guar growth and seed yield due to unfavorable environmental conditions. Changes in temperature, photoperiod, and precipitation affect plant height, number of branches per plant, number of leaves per plant, above ground dry biomass, seed yield characters (number of pods per plant, number of seeds per pod, 1000 seed weight, Harvest Index) and seed yield of guar. Planting date also affect maturity of guar. Low temperature and high humidity at maturity reduce seed yield and seed quality. High mean air temperature, long photoperiod and dry weather stimulate photosynthetic rate resulting in higher above ground dry biomass and seed yield of guar. Low temperature and high humidity affect number of pods and clusters per plant, 1000 seed weight and harvest index, hence reduce seed yield both quantitatively and qualitatively. In general, combined negative effect of low temperature, high humidity and short photoperiod produce low seed yield for delayed planting.