Impact of water stress on growth reserves and re-growth of Themeda triandra (Forssk) following defoliation

The influence of water stress and defoliation on the concentration of total non-structural carbohydrates (TNCC) and water-soluble protein (WSPC) as growth reserves after defoliation were determined in the indigenous C 4 semi-arid grass species Themeda triandra during three growth stages (vegetative,...

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Bibliographic Details
Published in:African journal of range & forage science 2003-03, Vol.20 (1), p.41-45
Main Authors: Oosthuizen, I.B, Snyman, H.A. (Free State Univ., Bloemfontein (South Africa). Animal, Wildlife and Grassland Science Dept.)
Format: Article
Language:English
Subjects:
CLIMA SEMIARIDO
CLIMAT SEMI ARIDE
DEFOLIACION
DEFOLIATION
DROUGHT STRESS
ESTRES DE SEQUIA
GROWTH RATE,SOUTH AFRICA
GROWTH RESERVE
GROWTH STAGES
SEMIARID CLIMATE
STRESS DU A LA SECHERESSE
THEMEDA TRIANDRA
TRANSLOCATION
WATER STRESS
WATER-SOLUBLE PROTEIN
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Summary:The influence of water stress and defoliation on the concentration of total non-structural carbohydrates (TNCC) and water-soluble protein (WSPC) as growth reserves after defoliation were determined in the indigenous C 4 semi-arid grass species Themeda triandra during three growth stages (vegetative, piping and reproductive) and in three plant parts (roots, stubble and leaves). Four water stress treatments (T1 = 0-25%, T2 = 25-50%, T3 = 50-75% and T4 = 75-100% depletion of plant available water) were applied to the plants in pots in a glasshouse. The TNCC declined drastically after severe defoliation over all the water treatments (P < 0.05), in all the plant parts (P < 0.05) and for all the growth stages (P < 0.05), while the TNCC did not recover (P < 0.05) (to the TNCC values as before defoliation) within 6 days after defoliation. The WSPC in the leaves increased from after defoliation, up to day 6 over all the water treatments (P < 0.05) and for all the growth stages (P < 0.05). Non-structural carbohydrates serve as the most important growth reserve and are utilised for re-growth after severe defoliation. Water-soluble protein can also be utilised as growth reserve, but only as an emergency measure for up to two days after defoliation. These results could make a meaningful contribution to ensure sustainable utilisation of the grassland ecosystem in semi-arid areas.
ISSN:1022-0119
1727-9380
0256-6702
DOI:10.2989/10220110309485796