Guar (Cyamopsis tetragonoloba L.) is an annual legume and valuable industrial crop due to high galactomannan content of its seed, which could be a potential alternative food and feed crop in the arid and semi-arid regions of the world. The aim of this study was to investigate the influence of three different planting dates on phenological, physiological and metabolic attributes of guar (Cyamopsis tetragonoloba L.) landraces and cultivars (with different origin) in an arid environment in south-east Iran. Four guar cultivars (RGC-986, RGC-1033, RGC-1066, and HG-563) with origin of India and 6 Iranian landraces (Grembite, Iranshahr, Saravan, Sarbaz, Dalgan, and Pishen) showed significant (P < 0.05) variations on number of leaf, stem diameter, leaf angle, leaf area, days to vegetative phase, days to pod initiation, days to 50% podding, plant height, days to flower initiation, days to maturity, pod length, number of pod per cluster, number of seeds per pod, seed yield, carbohydrate content, protein content, total chlorophyll content, seed gum (galactomannan) content, number of pods per plant, number of seeds per plant, 100-seed weight upon different planting dates. Results indicated the maximum and minimum carbohydrate content (32.1 and 25.2%) was achieved in August planting for Saravan and RGC-986, respectively. Galactomannan content ranged between 23.3% (for August planting of Sarbaz) and 28.6% (for May planting of RGC-986). Days to flowering showed negative but significant correlation with pod length (r0.01=−0.279), seed yield (r0.01=−0.460) and 100 seed weight (r0.01=−0.472). In particular, local landraces showed better chemical composition for carbohydrate under warmer planting date (August) and protein under May planting than those of cultivars. Results of our study indicated that local landrace of Grembite and Indian cultivar of RGC-986 are superior ones based on the analysis of the most morphological and phytochemical traits data under different sowing dates, the
