Response of leaf temperature to soil water deficit in cashew (Anacardium occidentale L.) seedlings
2005
Pitono, J.(Okayama Univ. (Japan)) | Tsuda, M. | Hirai, Y.
The control of transpiration in cashew seedlings is important to enable them to cope with drought-prone environments. The response of the leaf temperature to soil water deficit, as an indicator of transpiration, was examined in 10 cashew strains from Indonesia the seedlings were grown in 4.3 liter pots fined with soil for about 3 months, and irrigation was withheld from half of these pots to reduce the content of soil water, while the remaining pots were well-watered. During midday on sunny days, the leaf temperature of the well-watered plants and plants subjected to the soil water deficit was determined with a handheld infrared thermometer as well as the temperature of a wet filter paper and a dry leaf. Soil water content was also determined. Based on these data the leaf temperature ratio (LTR) as a relative value of leaf transpiration to potential evaporation (wet filter paper) was calculated. In MDR and A3-l, LTR was smaller than in the other eight strains. LTR in the well-watered plants (LTR0)) ranged from 0.74- 0.87, and strains MDR and A3-1 showed a low LTR0. In these two strains, LTR decreased more sensitively in response to the decrease of the soil water content. These results indicate that MDR and A3-1 may conserve soil water better because their transpiration rate was low under both well-watered and drought conditions.
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