Interactive Effects Of Water Stress Research Articles

Isotopic and Water Relation Responses to Ozone and Water Stress in Seedlings of Three Oak Species with Different Adaptation Strategies

The impact of global changes on forest ecosystem processes is based on the species-specific responses of trees to the combined effect of multiple stressors and the capacity of each species to acclimate and cope with the environment modification. Combined environmental constraints can severely affect plant and ecological processes involved in plant functionality. This study provides novel insights into the impact of a simultaneous pairing of abiotic stresses (i.e., water and ozone (O3) stress) on the responses of oak species. Water stress (using 40 and 100% of soil water content at field capacity—WS and WW treatments, respectively) and O3 exposure (1.0, 1.2, and 1.4 times the ambient concentration—AA, 1.2AA, and 1.4AA, respectively) were carried out on Quercus robur L., Quercus ilex L., and Quercus pubescens Willd. seedlings, to study physiological traits (1. isotope signature [δ13C, δ18O and δ15N], 2. water relation [leaf water potential, leaf water content], 3. leaf gas exchange [light-saturated net photosynthesis, Asat, and stomatal conductance, gs]) for adaptation strategies in a Free-Air Controlled Exposure (FACE) experiment. Ozone decreased Asat in Q. robur and Q. pubescens while water stress decreased it in all three oak species. Ozone did not affect δ13C, whereas δ18O was influenced by O3 especially in Q. robur. This may reflect a reduction of gs with the concomitant reduction in photosynthetic capacity. However, the effect of elevated O3 on leaf gas exchange as indicated by the combined analysis of stable isotopes was much lower than that of water stress. Water stress was detectable by δ13C and by δ18O in all three oak species, while δ15N did not define plant response to stress conditions in any species. The δ13C signal was correlated to leaf water content (LWC) in Q. robur and Q. ilex, showing isohydric and anisohydric strategy, respectively, at increasing stress intensity (low value of LWC). No interactive effect of water stress and O3 exposure on the isotopic responses was found, suggesting no cross-protection on seasonal carbon assimilation independently on the species adaptation strategy.

Sorghum radiation use efficiency and biomass partitioning in intercrop systems

The objective of intercropping is to improve resource efficiencies for land, water and radiation. Few studies have focused on the interactive effects of water stress on radiation use efficiency (RUE) in an intercrop system. The study determines the effect of intercropping sorghum with either cowpea or bottle gourd on RUE and biomass accumulation in response to water stress. This was assessed using a split-plot design with crop sequences sole sorghum, sole cowpea, and sole bottle gourd and intercrop systems sorghum–cowpea and sorghum–bottle gourd assigned as sub-plots arranged in randomised complete blocks within main plots, water regimes: full irrigation, deficit irrigation and rainfed. We quantified specific leaf area, leaf area index as well as biomass accumulation and partitioning. Extinction coefficient, intercepted photosynthetic active radiation (IPAR) and RUE for biomass (RUEb) and grain (RUEg) were also determined. Under rainfed conditions, intercropping with either cowpea (26%) or bottle gourd (62%) improved sorghum leaf area. A reduction in specific leaf area was observed for sorghum when it was intercropped with either cowpea (−20%) or bottle gourd (−19%). Under full irrigation, sorghum stems constituted a larger proportion (62%) of final biomass in comparison to sorghum under deficit irrigation (52%) and rainfed conditions (50%). Intercropping sorghum with either cowpea or bottle gourd improved IPAR (38%), RUEb (93%) and RUEg (11%) under rainfed conditions. This study showed that under water-limited conditions intercropping reduced sorghum stem mass and increased canopy size, radiation interception, and grain yield and improved RUE. In agreement with our proposition, water availability was closely associated with radiation use efficiency. Intercropping can be recommended for semi-arid environments since it improves RUE and sorghum biomass and grain yield.

Interactive effects of water stress, container size and fertilizer on survival, gas exchange and morphological traits of Quillaja saponaria seedlings

Interactive effects of water stress, container size and fertilizer on survival, gas exchange and morphological traits of Quillaja saponaria seedlings

Effects of water stress and fertilization on leaf gas exchange and photosynthetic light-response curves of Bothriochloa ischaemum L.

Bothriochloa ischaemum L. is an important species in many temperate regions, but information about the interactive effects of water stress and fertilization on its photosynthetic characteristics was inadequate. A pot experiment was conducted to investigate the effects of three water [80% (HW), 40% (MW), and 20% (LW) of field capacity (FC)] and four fertilization regimes [nitrogen (N), phosphorus (P), nitrogen with phosphorus (NP), and no fertilization] on leaf photosynthesis. Leaf gas exchange and photosynthetic light-response curves were measured at the flowering phase of B. ischaemum. Water stress decreased not only the leaf gas-exchange parameters, such as net photosynthetic rate (PN), stomatal conductance (gs), transpiration rate (E), and water-use efficiency (WUE) of B. ischaemum, but also downregulated PN-photosynthetically active radiation (PAR) curve parameters, such as light-saturated net photosynthetic rate (PNmax), apparent quantum efficiency (AQE), and light compensation point (LCP). Fertilization (N, P, and NP) enhanced the daily mean PN values and PNmax under the HW regime. Addition of N (either alone or with P) improved the photosynthetic capacity of B. ischaemum under the MW and LW regimes by increasing PN, PNmax, and AQE and reducing dark respiration rate and LCP, but the addition of P alone did not significantly improve the photosynthetic performance. Decline in PN under each fertilization regime occurred during the day and it was caused mainly by nonstomatal limitation. Our results indicated that water was the primary limiting factor for photosynthesis in B. ischaemum, and that appropriate levels of N fertilization improved its potential photosynthetic capacity under water-deficit conditions.

POTASSIUM SULFATE IMPROVES WATER DEFICIT TOLERANCE IN MELON PLANTS GROWN UNDER GLASSHOUSE CONDITIONS

Interactive effects of water stress and potassium (K) on some physiological attributes and nutritional status of melon (Cucumis melo L. cv. ‘Tempo F1’) plants were assessed in a pot experiment. Treatments used were: (1) control or well-watered (WW) + K1, (2) WW + K2, (3) WW + K3, (4) water stress (WS) + K1, (5) WS + K2, and (6) WS + K3. Water stress (WS) was imposed by maintaining the moisture level equivalent to 50% pot capacity, whereas well-watered (WW) pots (control) were maintained at full pot capacity (100% PC). Hoagland's nutrient solution was modified to supply K as potassium sulfate (K2SO4) at 6, 9, and 12 mM for K1, K2, and K3 treatments, respectively. Water stress reduced fruit yield, total dry matter, chlorophyll content and relative water content (RWC), but increased proline accumulation in the melon plants. However, additional supply of K as 3 or 6 mM significantly enhanced all the earlier mentioned physiological parameters, but the values were still not the same as the levels of the control treatment. Water stress also reduced leaf calcium (Ca) and K of the melon plants, but additional supply of K to the root zone increased the levels of both nutrients much higher than those at the control (C) treatment. Our study revealed that additional supply of K improved water stress tolerance in melon plants by enhancing chlorophyll, relative water content and concentrations of some essential nutrients in leaves.

Interactions of water stress and solar irradiance on the physiology and biochemistry of Ligustrum vulgare

We studied the interactive effects of water stress and solar irradiance on physiological and biochemical traits in Ligustrum vulgare L., with special emphasis on antioxidant enzymes and flavonoids. Water relations, photosynthetic performance, plant growth, activities of antioxidant enzymes and of phenylalanine-ammonia-lyase, and concentrations of nonstructural carbohydrates and phenylpropanoids were measured in plants growing in 12% (shade) or 100% (sun) sunlight and supplied with 100 or 40% of daily evapotranspiration-demand over a 4-week period. The mild water stress treatment caused leaf water potential and relative water content to decline on average by -0.22 MPa and 4.5%, respectively. In response to the water stress treatment, photosynthetic rates decreased more in sun plants than in shade plants, likely because of declines in photosystem II photochemistry, apparent maximum rate of carboxylation and apparent maximum electron transport rate coupled with significant reductions in stomatal conductance. Antioxidant enzymatic activities, which were much greater in sun leaves than in shade leaves under well-watered conditions, increased (particularly the enzymatic activities associated with hydrogen peroxide removal) in response to water stress only in shade leaves. Antioxidant phenylpropanoids, particularly quercetin and luteolin derivatives, markedly increased in response to full sunlight irrespective of water treatment; however, antioxidant phenylpropanoid concentrations increased in response to water stress only in shade leaves. We suggest that: (1) assimilated carbon in sun plants was used largely to support an effective antioxidant system capable of countering water-stress-induced oxidative damage--an example of cross tolerance; and (2) in shade plants, carbon was also diverted from growth to counter oxidative damage driven by the mild water-stress treatment. Both findings are consistent with the nearly exclusive distribution of L. vulgare in well-watered, partially shaded Mediterranean areas.

Growth of Lemon (<i>Citrus Limon</i> L. Buru) in response to Water Stress and shading

A greenhouse study was conducted to determine if the effects of water stress and shade on the growth of lemon are interactive or independent. The main effects of water stress significantly decreased number and surface area of young and old leaves, fresh and dry weight of leaves, flushes and whole plants as well as proportion of dry matter partitioned allocated to leaves. The main effects of shade significantly decreased number and surface area of young leaves, canopy volume, as well as fresh and dry weight of young leaves, flushes and whole plant. Water trees generally had more severe effects than shade. The interactive effects of water stress and shade were significant for fresh and dry weight of young leaves and whole plant. Since total dry matter accumulation is a very important growth index, the effects of water stress and shade on the vegetative growth of lemon are considered interactive. Keywords: Citrus, ‘Eureka', lemon, shade, water stress, vegetative growth. Nigerian Journal of Horticultural Science Vol. 10 2005: pp. 12-17

Acclimation to light in seedlings of Quercus petraea (Mattuschka) Liebl. and Quercus pyrenaica Willd. planted along a forest-edge gradient

Photosynthetic acclimation of two co-occurring deciduous oaks (Quercus petraea and Quercus pyrenaica) to a natural light gradient was studied during one growing season. In the spring of 2003, 90 seedlings per species were planted along a transect resulting from a dense Pinus sylvestris stand, an adjacent thinned area and a 10-m-wide firebreak (16.5–60.9% Global Site Factor (GSF)). In two dates of the following summer, we measured leaf gas exchange, carboxylation efficiency (CE), chlorophyll and nitrogen content, light–response curves of chlorophyll a fluorescence parameters, and leaf mass per area (LMA). Summer was mild, as evidenced by leaf predawn water potential (Ψpd), which reduced the interactive effect of water stress on the response of seedlings to light. Q. pyrenaica had higher LMA, CE, stomatal conductance (g s max) and photosynthesis per unit area $$(A_{\max }^a )$$ than Q. petraea at all growth irradiances. $$A_{\max }^a$$ , LMA, g s max and electron transport rate (ETR) all increased with light availability (GSF) in a similar fashion in both species. Light had also a clear effect on the organization of Photosystem II (PS II), as deduced by chlorophyll a fluorescence curves. Chlorophyll concentration (Chlm) decreased with increasing light availability in Q. pyrenaica but it did not in Q. petraea. Seedlings of Q. petraea acclimated to higher irradiances showed a greater non-photochemical quenching (NPQ) than those of Q. pyrenaica. This suggests a higher susceptibility to high light in Q. petraea, which would be consistent with a better adaptation to shade, inferred from the lower LMA or the lower rate of photosynthesis.

Interactive effects of water stress and xylem-limited bacterial infection on the water relations of a host vine

Xylella fastidiosa, a xylem‐limited bacterial pathogen that causes bacterial leaf scorch in its hosts, has a diverse and extensive host range among plant species worldwide. Previous work has shown that water stress enhances leaf scorch symptom severity and progression along the stem in Parthenocissus quinquefolia infected by X. fastidiosa. The objective here was to investigate the mechanisms underlying the interaction of water stress and infection by X. fastidiosa. Using the eastern deciduous forest vine, P. quinquefolia, infection and water availability were manipulated while measuring leaf water potentials (ΨL), stomatal conductance (gs), whole shoot hydraulic conductance (Kh), per cent xylem embolism, and xylem vessel dimensions. No significant differences in any of the physiological measurements were found between control and infected plants prior to drought. Drought treatment significantly reduced ΨL and gs at all leaf positions throughout the day in late summer in both years of the study. In addition, infection significantly reduced ΨL and gs in the most basal leaf positions in late summer in both years. Whole shoot hydraulic conductance was reduced by both low water and infection treatments. However, per cent embolized vessels and mean vessel diameter were affected by drought treatment only. These results imply that the major effect of infection by X. fastidiosa occurs due to reduced hydraulic conductance caused by clogging of the vessels, and not increased cavitation and embolism of xylem elements. The reduced Kh caused by X. fastidiosa infection acts additively with the water limitation imposed by Drought stress.

Interactive effects of water stress and xylem-limited bacterial infection on the water relations of a host vine.

Xylella fastidiosa, a xylem-limited bacterial pathogen that causes bacterial leaf scorch in its hosts, has a diverse and extensive host range among plant species worldwide. Previous work has shown that water stress enhances leaf scorch symptom severity and progression along the stem in Parthenocissus quinquefolia infected by X. fastidiosa. The objective here was to investigate the mechanisms underlying the interaction of water stress and infection by X. fastidiosa. Using the eastern deciduous forest vine, P. quinquefolia, infection and water availability were manipulated while measuring leaf water potentials (psi(L)), stomatal conductance (g(s)), whole shoot hydraulic conductance (K(h)), per cent xylem embolism, and xylem vessel dimensions. No significant differences in any of the physiological measurements were found between control and infected plants prior to drought. Drought treatment significantly reduced psi(L) and g(s) at all leaf positions throughout the day in late summer in both years of the study. In addition, infection significantly reduced psi(L) and g(s) in the most basal leaf positions in late summer in both years. Whole shoot hydraulic conductance was reduced by both low water and infection treatments. However, per cent embolized vessels and mean vessel diameter were affected by drought treatment only. These results imply that the major effect of infection by X. fastidiosa occurs due to reduced hydraulic conductance caused by clogging of the vessels, and not increased cavitation and embolism of xylem elements. The reduced K(h) caused by X. fastidiosa infection acts additively with the water limitation imposed by Drought stress.

Interactive effect of water stress and nitrogen on plant height and root length of wheat (Triticum aestivum L.)

Interactive effect of water stress and nitrogen on plant height and root length of wheat (Triticum aestivum L.)

Interactive Effect of Water Stress and Nitrogen on Yield and Biomass of Wheat (Triticum aestivum L.)

Interactive Effect of Water Stress and Nitrogen on Yield and Biomass of Wheat (Triticum aestivum L.)

Interactive effects of water stress, temperature and nutrients in the seed germination of three desert plants

A trifactorial investigation on the combined effects of reduced water potential (Ψm)) temperature (T) and nutrients (Nr) on the seed germination of Prosopis, Calotropis and Sorghum has been conducted. Each of the factors has a significant effect on emergence and elongation of both the radicle and the hypocotyl (and plumule in Sorghum). Nr has no significant effect on hypocotyl elongation in Prosopis or Calotropis. Bifactorial and trifactorial interactions also have significant effects on different germination phases, except for interactions of Nr with other factors (Ψm or T) in elongation of the hypocotyl in Prosopis and Calotropis, as well as radicle emergence in the three genera. Matric potential (Ψm) has the predominant effect on plumule and radicle emergence in Sorghum and Calotropis, and on hypocotyl elongation in the latter. The effect of the interaction (Ψm × T) is predominant in dry matter allocation in different seed organs of Calotropis and storage tissue of Prosopis. Otherwise, temperature had the predominant effect in most events of germination of the seeds investigated.

The interactive effect of water stress and temperature on the CO2 response of photosynthesis in Salix.

The interactive effect of water stress and temperature on the CO2 response of photosynthesis in Salix.