Factors involved in alleviating water stress by partial crop removal in pear trees.
نویسندگان
چکیده
We studied the relief of water stress associated with fruit thinning in pear (Pyrus communis L.) trees during drought to determine what mechanisms, other than stomatal adjustment, were involved. Combinations of control irrigation (equal to crop water use less effective rainfall) and deficit irrigation (equal to 20% of control irrigation), fruit load (unthinned and thinned to 40 fruits per tree) and root pruning (pruned and unpruned) treatments were applied to pear (cv. 'Conference') trees during Stage II of fruit development. Daily patterns of midday stem water potential (Psi(stem)) and leaf conductance to water vapor (g(l)) of deficit-irrigated trees differed after fruit thinning. In response to fruit thinning, gl progressively declined with water stress until 30 days after fruit thinning and then leveled off, whereas the effects of decreased fruit load on Psi(stem) peaked 30-40 days after fruit thinning and then tended to decline. Soil water depletion was significantly correlated with fruit load during drought. Our results indicate that stomatal adjustment and the resulting soil water conservation were the factors determining the Psi(stem) response to fruit thinning. However, these factors could not explain differences in daily patterns between g(l) and Psi(stem) after fruit thinning. In all cases, effects of root pruning treatments on Psi(stem) in deficit-irrigated trees were transitory (Psi(stem) recovered from root pruning in less than 30 days), but the recovery of Psi(stem) after root pruning was faster in trees with low fruit loads. This behavior is compatible with the concept that the water balance (reflected by Psi(stem) values) was better in trees with low fruit loads compared with unthinned trees, perhaps because more carbon was available for root growth. Thus, a root growth component is hypothesized as a mechanism to explain the bimodal Psi(stem) response to fruit thinning during drought.
منابع مشابه
Nitric oxide ameliorates salinity tolerance in Pyrodwarf pear (Pyrus communis) rootstocks by regulating polyamine content
Nitric oxide (NO), an endogenous signaling molecule, is involved in various physiological processes and stress responses in plants. In the present research, Pyrodwarf pear (Pyrus communis) rootstocks were grown by nutrient solution to investigate the effects of sodium nitroprusside (SNP) application as an NO donor at 0, 0.1, 0.5, and 1 mM levels on plant stress tolerance, content of ma...
متن کاملPhenotypic plasticity of stem water potential correlates with crop load in horticultural trees.
Conceptual models accounting for the influence of source:sink ratio on water relations of trees are theoretically relevant from a physiological perspective and practically important for irrigation scheduling. Midday stem water potential of horticultural trees often declines with increasing crop load but the actual response depends on environmental, management and plant factors. Here we advance ...
متن کاملIsolation of Brassica napus MYC2 gene and analysis of its expression in response to water deficit stress
Manipulation of stress related transcription factors to improve plant stress tolerance is a major goal of current biotechnology researches. MYC2 gene encodes a key stress-related transcription factor involved in Jasmonate (JA) and abscisic acid (ABA) signaling pathways in Arabidopsis. Brassica napus, as a globally important oilseed crop, is a close relative of Arabidopsis. In the present study...
متن کاملEffects of water stress cycles on turgor maintenance processes in pear leaves (Pyrus communis).
Effects of water deficits on leaf turgor maintenance processes were analyzed for pear trees (Pyrus communis L. cv. "Barlett") grown in 120-liter containers. Four irrigation treatments were applied: a well-watered control treatment, a spring water stress cycle (Sp), a summer water stress cycle (Su), and a spring plus summer water stress cycle (Sp + Su). For the Sp treatment, water application wa...
متن کاملWater stress and crop load effects on fruit fresh and dry weights in peach (Prunus persica).
Effects of water stress on fruit fresh and dry weights were investigated in peach trees, Prunus persica (L.) Batsch., with varying crop loads: light, moderate and heavy. In well-watered controls, tree water status was independent of crop load. In trees receiving reduced irrigation, the degree of water stress increased with increasing crop load. Water stress induced fruit fresh weight reductions...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Tree physiology
دوره 28 9 شماره
صفحات -
تاریخ انتشار 2008