The influence of water stress on non-structural carbohydrate concentrationin Themeda triandra

The objective of this study was to determine the influence of four differen t watering treatments (T1 = 75-100%, T2 = 50-75%, T3 = 25-50% and T4 = 0-25 % of Field Water Capacity) on the concentration of total non-structural car bohydrates during three growth stages (vegetative, pipe and reproductive) a nd also in three plant parts (roots, stubble and leaves) of the indigenous C-4 grass species Themeda triandra. The total non-structural carbohydrate c oncentration (TNCC) was higher in all the plant parts (P less than or equal to0.05) as well as all the growth stages (P less than or equal to0.05), in T4 than T1. The results confirm that total non-structural carbohydrates ar e allocated las growth reserves) to certain plant parts with increased wate r stress, with the largest allocation to the stubble. Because a mid-summer drought is more the rule than the exception in semi-arid areas, severe defo liation of Themeda triandra in the pipe growth stage during these condition s will be extremely detrimental to the survival of this key forage plant.