• Journal of Plant Biotechnology
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• v.44 no.2
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• pp.142-148
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• 2017

Drought stress is one of the important factors that restrict the expansion of Hevea brasiliensis cultivation to non-traditional regions experiencing extreme weather conditions. Plants respond to drought stress by triggering expression of several drought responsive genes including transcription factors which in turn trigger expression of various downstream signalling pathways and adaptive networks. Expression of such drought responsive genes may revert back to their original level upon re-watering. However, no reports are available on such phenomenon in Hevea and hence, this study was initiated. For this purpose, NAC transcription factor (NAC tf) was chosen as candidate gene. Its expression levels were monitored under intermittent drought as well as irrigated conditions in two clones (RRII 105 and RRIM 600) of H. brasiliensis with contrasting tolerance level. Copy number of NAC tf was found similar in both the clones. Expression of NAC tf was found highly up-regulated in RRIM 600 (a relatively drought tolerant clone) than in RRII 105 (a relatively drought susceptible clone) throughout the drought incidences which upon re-watering, reached back to its original levels in both the clones. The study indicated the existence of an association between expression of NAC tf and drought tolerance trait exhibited by the tolerant clone RRIM 600. The study also proves the influence of drought and re-watering on the leaf photosynthesis and expression of NAC tf in H. brasiliensis.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.6
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• pp.746-750
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• 1998

This experiment was conducted to investigate the water requirement of exercising sheep. Nine Merino ewes were allocated into three groups differing in water supply after exercise, group 1(G1) supplied water ad libitum, group 2 (G2) supplied with water twice a day, and group 3 (G3) supplied with water once a day. The ewes were exercised outdoors using a circular exercising machine at a speed of 5 km/h for 1 hour for 12 consecutive days. Total daily water intake (TDWI) of animals in G3 was significantly lower (p < 0.05) than that of those in G1 and G2. TDWI of the 2 later groups was not different. TDWI of G3 was about 60% of that of G1. Feed intake of G3 was significantly (p < 0.05) lower than that of the other two groups. Immediately after exercise, rectal temperature (RT) of animals in G1 was significantly (p < 0.05) lower than those in the other groups. Respiration rate (RR) of animals in all three groups was not significantly different. Faecal moisture of animals in G3 was significantly lower (p < 0.05) than those in the other groups. The results indicate that for optimum productivity sheep should be given water at least twice a day.