Pheno-physiological modelling for cv. Khieo Sawoei and Nam Dommai mangoes grown in tropical and subtropical climates of Thailand

Sustainable productivity in mango could be enhanced by developing the crop management practices. This approach is generally provided by improved knowledge of the interaction between tree phenology and physiology and environment. The phenological cycles and the associated physiological change in cvs. Khieo Sawoei and Nam Dok Mai mangoes were observed in Chiangrai province as a subtropical region and in Phichit and Sikaket provinces as tropical regions of Thailand. The climatic data conditions were also monitored over four cropping years during 1995 to 1998. There was sufficient flowering in both cultivars at all three experimental sites to produce a reasonable crop even the degrees and timing varied from year to year. Flowering at Chiangrai was estimated ranging between 64.5-82.0 percent and 60.5-85.0 percent for the Khieo Sawoei and Nam Dok mai, respectively. It ranged between 27-80 percent and 63-100 percent at Phichit and between 25-70 percent and 60-82.5 percent at Sisaket for the Khieo Sawoei and Nam Dok Mai, respectively. Inflorescence development in both cultivars at Chiangrai of each year occurred similarly commencing between early january and early February and terminating between early and late March. For Phichit and Sisaket, there was similar variation in such development period with wider time intervals for each cultivar. The inflorescence in the Khieo Sawoei developed commencing between late December and mid February and completing between early February and mid March while the development in the Nam Dok Mai was estimately 1 to 2 weeks earlier. Low fruit set and retention capacity was determined in both cultivars at all three sites with lower yields in the Khieo Sawoei. Vegetative flushing occurred mostly twice during the annual growth cycle at the Phichit and Sisaket sites. The first flush occurred about 4 to 6 weeks after harvest and the following 10-16 weeks for the second flush. Some important physiological parameters were also observed including carbon dioxide assimilation rate, starch concentration in various tree parts, chlorophyll fluorescence ratio and leaf chlorophyll content. Their seasonal changes were investigated and the relationships with growth, flowering and fruit set were also described in details.