ESTABLISHMENT OF PROTOCOL FOR CARBOHYDRATE ANALYSIS AND MONITORING SEASONAL VARIATIONS BETWEEN CARBOHYDRATES AND NITROGEN LEVELS IN GARCINIA MANGOSTANA (MANGOSTEEN)

A Protocol for carbohydrate analysis was established between leaf positions (Leaf 1-5 in the x-axis) and the amount of carbohydrates (y-axis) for fructose, glucose and sucrose in mangosteen leaves. At Leaf 1 (the first, fully-expanded leaf), none of the points for fructose, glucose and sucrose intercepted. The points of interception between glucose and sucrose occurred at Leaf 2 and for fructose and sucrose between Leaves 2 and 3 suggesting that Leaf 2 should be taken as the indicator leaf for the entire analysis. Seasonal variations between carbohydrate (fructose, glucose and sucrose) and nitrogen levels in Leaf 2 along the shoot were monitored monthly from January 2004 till December 2004 on mature mangosteen trees. The amount of fluctuation for sucrose was greater compared to that for fructose and glucose. During flowering in February, fructose, glucose and sucrose were at 0.20 mg/ml, 0.45 mg/ml and 0.34 mg/ml, respectively, that is at their lowest levels in the year. When shoot flushing occurred in July, fructose, glucose and sucrose were at 0.96 mg/ml, 1.26 mg/ml and 1.79 mg/ml, respectively. These sugars were higher at flushing (July) compared to flowering (February) indicating that more reserves were being utilised for flowering. However, nitrogen levels between January and December ranged from 1.18% (flushing-July) to 1.51% implying that nitrogen was more in demand for flushing. The ratios of carbohydrate: nitrogen (CHO:N) were contradicting during flushing and flowering suggesting that there might be a relationship between these two for the vegetative and reproductive phases in mangosteen.