Stomatal Responses to Leaf Water Potentials of Drip Irrigated Peach {Prunus persica)

ABSTRACT THIS study evaluated the effect of varying levels of water stress on leaf resistance, leaf water potential and transpiration of drip irrigated peach [Prunus persica (L.) Batsch]. Leaf resistances were significantly higher for the 1-emitter tree indicating it to be the most severely stressed. Leaf water potential and transpiration rates were also lower in these trees. Leaf resistances decreased exponentially with increasing solar radiation and curvilinearly with increasing vapour deficit. Stomata responded slower in stressed trees. Leaf resistances were lower at leaf water potential above —20 bars and increased at leaf water potential below —21 for the well watered trees. In stressed trees the threshold value was lowered to —25 bars. Leaf resistance and leaf water potential decreased until its threshold value, after which both increased.