Carbon discrimination, water-use efficiency, nitrogen and phosphorus nutrition of the host / mistletoe pair Eucalyptus behriana F. Muell and Amyema miquelii (Lehm. ex Miq.) Tiegh. at permanently low plant water status in the field

Trees ◽  
1992 ◽  
Vol 7 (1) ◽  
Author(s):  
Manfred K�ppers
1992 ◽  
Vol 43 (5) ◽  
pp. 1019 ◽  
Author(s):  
AL Garside ◽  
RJ Lawn ◽  
RC Muchow ◽  
DE Byth

Plant and soil water status, crop water use and water use efficiency, as affected by irrigation treatment, were monitored over two seasons for soybean cv. Ross, sown in the late wet season in the Ord Irrigation Area in north Western Australia. Irrigation treatments were, in both seasons, furrow irrigation after cumulative open pan evaporative losses of 30, 60 120 and 240 mm, and in the second year, an additional treatment, saturated soil culture (continuous furrow irrigation, analogous to irrigation after 0 mm pan evaporation). As expected, during periods of strong evaporative demand plant water status, as indicated by leaf water potential and leaf conductance of water vapour, was consistently greater in the more frequently irrigated treatments, while soil water depletion occurred to greater extent and depth in the less frequently irrigated treatments. However, total soil water use was directly proportional to crop growth, so that there was little evidence that water use efficiency was enhanced by restricting water supply in this environment. Indeed, efficiency of water use even under the continuous furrow irrigation system was comparable with that from other irrigation treatments. The responses are interpreted to imply that there is unlikely to be any economic advantage to the use of limited supplemental irrigation in this environment.


HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 647c-647
Author(s):  
L. Phavaphutanon ◽  
F.T. Davies ◽  
T.W. Boutton ◽  
S.A. Duray

Mycorrhizal (VAM) and phosphorus (P)-supplemented nonmycorrhizal neem plants (non-VAM) of comparable size and tissue nutrition were subjected to a slowly developing drought. VAM and non-VAM plants responded to drought similarly. However, mycorrhiza compensated for low P supply, allowing VAM plants to have comparable growth, tissue P, and other physiological parameters as non-VAM plants, which received higher P supply. Drought decreased growth, transpiration (E), photosynthetic rate (A), stomatal conductance (gs), and plant water status. Osmotic adjustment did not occur, but the relatively low osmotic potential of this species helped maintain turgor during drought. Plant water relations and A of stressed plants fully recovered in 24 hours after rehydration, while gs and E partially recovered. Instantaneous water use efficiency (A/E) increased during drought and recovery, except for a decrease at peak stress due to very low A. Carbon isotope discrimination (D) values of mature leaves remained constant regardless of mycorrhiza or drought. However, D decreased in expanding leaves that developed during a drought period, indicating an increased long-term water use efficiency of these leaves.


HortScience ◽  
2018 ◽  
Vol 53 (12) ◽  
pp. 1784-1790 ◽  
Author(s):  
Dalong Zhang ◽  
Yuping Liu ◽  
Yang Li ◽  
Lijie Qin ◽  
Jun Li ◽  
...  

Although atmospheric evaporative demand mediates water flow and constrains water-use efficiency (WUE) to a large extent, the potential to reduce irrigation demand and improve water productivity by regulating the atmospheric water driving force is highly uncertain. To bridge this gap, water transport in combination with plant productivity was examined in cucumber (Cucumis sativus L.) grown at contrasting evaporative demand gradients. Reducing the excessive vapor pressure deficit (VPD) decreased the water flow rate, which reduced irrigation consumption significantly by 16.4%. Reducing excessive evaporative demand moderated plant water stress, as leaf dehydration, hydraulic limitation, and excessive negative water potential were prevented by maintaining water balance in the low-VPD treatment. The moderation of plant water stress by reducing evaporative demand sustained stomatal function for photosynthesis and plant growth, which increased substantially fruit yield and shoot biomass by 20.1% and 18.4%, respectively. From a physiological perspective, a reduction in irrigation demand and an improvement in plant productivity were achieved concomitantly by reducing the excessive VPD. Consequently, WUE based on the criteria of plant biomass and fruit yield was increased significantly by 43.1% and 40.5%, respectively.


Author(s):  
C Ruggiero ◽  
G Angelino ◽  
S Ascione ◽  
A Napolitano

AbstractThe results of a two-year research project into burley tobacco are reported and discussed. Three irrigation levels (40, 80 and 120% restitution of evapotranspiration (ET)) were factorially combined with four levels of nitrogen fertilisation (0, 80, 160 and 240 kg ha). Leaf area, leaf and stem dry matter and root development were measured. We monitored the water status of the 0-90 cm soil layer, the plants and stomatal resistance. Relations were also studied between leaf turgor pressure and plant growth, between the irrigation regime and plant water status, and between root and shoot development. Finally, water use efficiency (WUE) and quality and quantity of cured leaves yields were evaluated. Nitrogen fertilisation did not affect plant water status, although it promoted plant growth, both in terms of leaf area and leaf and stem dry matter, and induced a yield increase in quantity and quality. Our trial showed little interaction between nitrogen fertilization level and water regime. Under such agronomic condition, the margins for increasing plant growth with nitrogen fertilization are limited, which is why application of nitrogen rates in excess of 160 kg haappear inadvisable. The difference in irrigation volumes led to a different soil water content which affected plant water status, stomatal functioning, plant growth, both in the roots and shoots, yield and quality of the cured leaves. The latter did not vary with the increase in water volume, while yield increased. Water use efficiency increased as the irrigation volume decreased and varied during the cropping cycle, increasing until early bloom, then decreasing. Relations between leaf turgor pressure and plant growth highlighted the different response of plants subjected to water stress compared with non-stressed plants.


1991 ◽  
Vol 71 (3) ◽  
pp. 695-702 ◽  
Author(s):  
J. M. Clarke ◽  
R. A. Richards ◽  
A. G. Condon

Increasing the water use efficiency (WUE) of wheat (Triticum spp.) has long been a goal in semiarid areas. Low rates of residual (cuticular) transpiration are thought to improve yield potential of wheat under dry conditions, although the linkage is tenuous. The objective of this work was to investigate the association of residual transpiration with water use, WUE, and leaf water status in hexaploid (T. aestivum L.) and tetraploid (T. turgidum L. var. durum) genotypes grown under two watering regimes in two glasshouse experiments. Single plants were grown in 0.1-m × 1-m (0.1-m × 0.5-m in exp. 2 low-stress treatment) PVC tubes filled with soil. The watering regimes consisted of weekly replenishment of water used (low stress), or addition of sufficient water to ensure plant survival (high stress). At anthesis, flag leaf residual transpiration (rate of water loss from excised leaves), stomatal conductance, relative water content (RWC), and osmotic potential (exp. 1 only) were measured. Water use was not correlated with residual transpiration rate in either experiment. Residual transpiration rate did not differ for the two stress treatments in exp. 1, but there were significant (P < 0.01) genotype by stress treatment interactions. Residual transpiration rate was not related to plant water status (leaf RWC or osmotic potential) as had been reported in other studies. Key words: Cuticular transpiration, water use efficiency, Triticum aestivum L., Triticum turgidum L. var. durum


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