Changes of total non-structural carbohydrates within shoots of 'Nam Dok Mai' mango after paclobutrazol application

Relationship between total non-structural carbohydrates (TNC) within shoots, leaf flushing and flowering of Nam Dok Mai mango after paclobutrazol application was evaluated. Following a paclobutrazol drench in June, 1997, vegetative growth of treated trees was completely inhibited. Paclobutrazol induced off-season flowering in September, 1997 while the control, non-treated trees still grew vegetatively producing another 2-3 flushes. On-season flowering occurred in late November, 1997 on both treated and non- treated trees, with lower flowering density in the treated trees. Changes of shoot TNC correlated with leaf flushing and flowering where TNC decreased significantly during leaf flushing and flower emergence. As vegetative growth was inhibited by paclobutrazol, shoot TNC tended to accumulate faster prior to off-season flowering. Changes of TNC in leaves and stems of current year shoots were greater than of one-year old shoots. A significant decrease of TNC on one-year old stem sections correlated with leaf flushing while TNC in one-year old leaves most of which were inside the canopy was fairly changed. Due to poor fruit set on both off- and on-season crops, the relationship between shoot TNC and fruit set was not clearly established.