Physiology of acclimation to salinity stress in pea (Pisum sativum)

Pea (Pisum sativum L.) seedlings were grown in half strength Hoagland solution and exposed to 0, 10, 25 mM NaCl and 2.5% PEG 6000 for 1 week (pre-treatment). Thereafter plants were exposed to 0 and 80 mM NaCl for 2 weeks (main treatment). The control plants were maintained in half strength Hoagland solution without NaCl. Various physiological parameters were recorded from control, pretreated and non-pretreated plants. There was no negative effect of the pre-treatments on growth (total fresh and dry matter production), and plants pre-treated with 10 mM NaCl had biomass accumulation equal to control plants. The beneficial effect of salt acclimation was also evident in the prevention of K⁺ leakage and Na⁺ accumulation, primary in roots, suggesting that here the physiological processes play the major role. 2.5% PEG 6000 was not as efficient as salt in enhancing salt tolerance and acclimation appears to be more related to ion-specific rather than osmotic component of stress. We also recorded an increase of the xylem K/Na in the salt acclimated plants. Therefore, the present study reveals that short-term exposure of the glycophyte P. sativum species activates a set of physiological adjustments enabling the plants to withstand severe saline conditions, and while acclimation takes place primary in the root tissues, control of xylem ion loading and efficient Na⁺ sequestration in mesophyll cells are also important components of this process.     

Effect of salinity on tomato fruit ripening

Tomato (Lycopersicon esculentum Mill) plants from various cultivars growing on half-strength Hoagland solution were exposed at anthesis to 3 or 6 grams per liter NaCl. Salinity shortened the time of fruit development by 4 to 15%. Fruits of salt-treated plants were smaller and tasted better than did fruits of control plants. This result was obtained both for ripe fruits tested on the day of picking and for those picked at 100% development and allowed to ripen at room temperature for 9 days. Percentage of dry weight, total soluble solids, and titratable acidity; content of reducing sugars, Cl⁻, Na⁺, and various pericarp pigments; and electrical conductivity of the juice were higher in fruits of saline-treated plants than they were in those of control plants, while the pH was lower. Ethylene and CO₂ evolution rates during ripening; as well as the activities of pectin methyl esterase, polymethylgalacturonase, and polygalacturonase; were also higher in fruits of the saline-treated plants. The treatment with 6 grams per liter NaCl shortened the fruit shelf life considerably.     

Effects of NaCl or Na<Subscript>2</Subscript>SO<Subscript>4</Subscript> salinity on plant growth,ion content and photosynthetic activity in <Emphasis Type="Italic">Ocimum basilicum</Emphasis> L.

Basil (Ocimum basilicum L., cultivar Genovese) plants were grown in Hoagland solution with or without 50 mM NaCl or 25 mM Na₂SO₄. After 15 days of treatment, Na₂SO₄ slowed growth of plants as indicated by root, stem and leaf dry weight, root length, shoot height and leaf area, and the effects were major of those induced by NaCl. Photosynthetic response was decreased more by chloride salinity than by sulphate. No effects in both treatments on leaf chlorophyll content, maximal efficiency of PSII photochemistry (F _v/F _m) and electron transport rate (ETR) were recorded. Therefore, an excess of energy following the limitation to CO₂ photoassimilation and a down regulation of PSII photochemistry was monitored under NaCl, which displays mechanisms that play a role in avoiding PSII photodamage able to dissipate this excess energy. Ionic composition (Na⁺, K⁺, Ca²⁺, and Mg²⁺) was affected to the same extent under both types of salinity, thus together with an increase in leaves Cl⁻, and roots SO₄ ²⁻ in NaCl and Na₂SO₄-treated plants, respectively, may have resulted in the observed growth retardation (for Na₂SO₄ treatment) and photosynthesis activity inhibition (for NaCl treatment), suggesting that those effects seem to have been due to the anionic component of the salts.     

Effects of short-term salinity on leaf gas exchange of the fig (Ficus carica L.)

The influence of short-term salinity (day 1–day 2: 50 mol m^–3 NaCl, day 3–day 7: 100 mol m^–3 NaCl in the nutrient solution) on leaf gas exchange characteristics were studied in two fig clones (Ficus carica L.), whose root mass had been varied in relation to the leaf area. The stomatal conductance was diminished by NaCl in the first week of treatment. NaCl slightly reduced the calculated intercellular partial pressure of CO₂. The net photosynthetic rate of plants with many roots was stimulated by NaCl on some days of the first week of treatment, whereas the net assimilation rate of the plants with few roots remained unaltered or decreased by NaCl. Only the assimilation of the salt-treated plants of one clone for some days during the first week of treatment seemed to be influenced by stomatal conductance. Nonstomatal factors were primarily responsible for the changes in CO₂ uptake in response to salt and/or root treatment. The water use efficiency increased during several days of the first week of NaCl treatment. Decreased stomatal conductance, increased water use efficiency and stimualtion of the net CO₂ assimilation rate appear to enhance salt tolerance during the first few days of salinity. ei]H Lambers     

Influence of calcium pretreatment on wheat germination on saline media

Summary Wheat grains (Triticum vulgare L. var. Lemhi 53) were pretreated for about 6 hours with various solutions. They were then rinsed and planted on filter paper moistened with NaCl solution in petri dishes. Percent germination was measured after 3 days. Germination of water pretreated seeds on 1% NaCl was 8 per cent, while pretreatment with 1% CaCl₂. 2H₂O resulted in 90 per cent germination on 1% NaCl. Pretreatment with sodium and potassium chlorides enhanced germination only slightly. The beneficial effects of calcium pretreatment could be duplicated only partially by increments of CaCl₂ to the NaCl germination medium. Preatreatment concentrations ranging from 1 to 5% CaCl₂. 2H₂O, and times ranging from 3 to 24 hours were about equally effective. The beneficial effect of pretreatment persisted even though the seeds were subsequently dried and planted several months later. Pretreatment with calcium resulted in about a 25 per cent reduction in Na²² uptake from the germination medium.United Nations F.A.O. André Meyer Post Doctoral Research Fellow, on leave from Sind University, Hyderabad, West Pakistan.     

RETRACTED ARTICLE: Effect of root-zone salinity and form of N on photosynthate partitioning in wheat (Triticum aestivum L.)

Carbon-14 pulse labeling technique was used to study the effect of rooting medium salinity and form and availability of N on growth and rhizodeposition of wheat (Triticum aestivum L.). Thirty days old plants grown in continuously aerated Arnon and Hoagland nutrient solution were subjected to ¹⁴C pulse labeling for 24 h and transferred to aqueous rooting medium containing 0, 150, and 300 mM NaCl in all combinations with different forms (calcium nitrate, ammonium sulphate, and ammonium nitrate) and amounts (0.5, 1.0, 1.5, and 2.0 times the standard N concentration (150 ppm) of Arnon and Hoagland plant growth medium). Plant samples immediately after pulse labeling, following 7 days of growth under different rooting medium conditions, and the freeze-dried rooting medium were analyzed for total C and ¹⁴C. Length and fresh/dry weight of root and shoot portions and calculated values of unaccounted ¹⁴C were determined. Presence of NaCl in the rooting medium led to a decrease in root and shoot portions. However, NO₃ ⁻-fed plants showed better growth than NH₄ ⁺-fed plants at all the three salinity levels. Salinity in rooting medium led to higher rhizodeposition and lower loss of ¹⁴C. Relatively higher proportion of ¹⁴C was released as rhizodeposits and retained in root/shoot portions of plants fed with NH₄ ⁺ or NH₄ ⁺+NO₃ ⁻, than those with NO₃ ⁻, while less was respired. The specific activity of the rhizodeposits (kBq ¹⁴C g⁻¹ C) was also higher under saline conditions. The rhizodeposits in NH₄ ⁺-fed plants were more highly labeled as compared to NO₃ ⁻-plants.     

Leaf gas exchange,water relations,nutrient content and growth in citrus and olive seedlings under salinity

The effects of salinity on growth, leaf nutrient content, water relations, gas exchange parameters and chlorophyll fluorescence were studied in six-month-old seedlings of citrus (Citrus limonia Osbeck) and rooted cuttings of olive (Olea europaea L. cv. Arbequina). Citrus and olive were grown in a greenhouse and watered with half strength Hoagland’s solution plus 0 or 50 mM NaCl for citrus, or plus 0 or 100 mM NaCl for olive. Salinity increased Cl⁻ and Na⁺ content in leaves and roots in both species and reduced total plant dry mass, net photosynthetic rate and stomatal conductance. Decreased growth and gas exchange was apparently due to a toxic effect of Cl⁻ and/or Na⁺ and not due to osmotic stress since both species were able to osmotically adjust to maintain pressure potential higher than in non-salinized leaves. Internal CO₂ concentration in the mesophyll was not reduced in either species. Salinity decreased leaf chlorophyll a content only in citrus.     

Involvement of abscisic acid in photosynthetic process in Hordeum vulgare L. during salinity stress

In Hordeum vulgare L. plants, NaCl stress imposed through the root medium for a period of 8 days decreased the rate of CO₂ assimilation, the chlorophyll and protein leaf content, and the activity of ribulose-1,5-bisphosphate carboxylase. The activity of phosphoenolpyruvate carboxylase was twofold over the control. Pretreatment with abscisic acid (ABA) for 3 days before salinization diminished the inhibitory effect of NaCl on the rate of CO₂ fixation. The leaf Na⁺ and Cl^– content decreased in ABA-pretreated plants. Both ABA and NaCl treatments led to an increase in the endogenous level of ABA in the plant leaves. Patterns of total proteins extracted from the leaves of control or ABA- and salt-treated plants were compared. Both ABA and NaCl induced marked quantitative and qualitative changes in the polypeptide profiles concerning mainly the proteins with approximately equal mobility. The results are discussed in terms of a possible role of ABA in increasing the salt tolerance when ABA is applied to the plants for a short period before exposure to salinity stress, thus improving the invulnerability to unfavorable conditions.Abbreviations RuBPC ribulose-1,5-bisphosphate carboxylase - PSII photosystem II - ABA abscisic acid - PEPC phosphoenolpyruvate carboxylase - DTTr dithiothreitol - BSA bovine serum albumin - ELISA enzyme-linked immunosorbent assay - SDS sodium dodecyl sulfate - PAGEr polyacrylamide gel electrophoresis     

Overcoming salinity inhibition of sorghum seed germination by hydration-dehydration treatment

Summary Sorghum (Sorghum bicolar (L) Moench cv EA-955 Serena) seeds, subjected or not to hydration-dehydration treatment were planted in distilled water, NaCl, and Na₂SO₄. When seeds were not hydrated-dehydrated the salts inhibited both seed germination and seedling vigour, and caused an increase in the per cent of abnormal seedlings. The salts neither inhibited seed germination nor increased the per cent of abnormal seedlings if the seeds were treated by hydration-dehydration. However, this treatment was not effective in overcoming the inhibitory effect of either NaCl or Na₂SO₄ on seedling vigour. Application of these principles in growing plants under saline environment is discussed.     

The possibility of predicting solute uptake and plant growth response from independently measured soil and plant characteristics

Summary The growth and nitrogen uptake response of rape plants to nitrate concentration at the root surface were studied in solution culture in a controlled environment cabinet over a period of 24 days. NO₃ ^– was supplied at the rates of 10^–5 M, 5×10^–5 M, 10^–4 M, 10^–3 M and 10^–2 M in solution and was maintained near these levels.With increasing mean N concentration in the tissues, the relative growth rate and leaf area ratio increased and unit leaf rate decreased slightly. Values of all three growth parameters decreased with plant age.The shoot: root dry weight ratios and their N content ratios increased with increasing mean per cent N in the plant. The length or surface area per unit dry weight of roots was correlated negatively with per cent N and positively with age.The maximum mean inflow of nitrate to rape roots decreased sharply with age. The concentration at which half maximal mean inflow was attained was 3.44×10^–5 M NO₃ ^–.     

Effect of sulphate waters on soil salinity,growth and yield of tomatoes

Summary Tomato (Lycopersicon esculentum var. VF 145) plants were grown with three soils in a greenhouse irrigated with water high in sulphates to determine their effects on soil salinity, growth and yield. Fruit fresh weights decreased by 53 and 40% when irrigated with water having 32 and 16 meq SO₄/l respectively, and no leaching was allowed, relative to irrigating with a half strength modified Hoagland solution. When a 0.3 leaching fraction was allowed the respective decrease in fruit fresh weights were 32 and 12% for the two levels of sulphate. Tops were less affected than were fruits. The electrical conductivity of solutions extracted from the soils during the growing period was highly correlated with the soil solution SAR (sodium adsorption ratio) and with Na and Cl concentrations. Leaching, although effective in controlling soil salinity caused by highly soluble salts, was ineffective in controlling salinity derived from SO₄.     

Effect of salinity on phosphate accumulation and injury in soybean

Many soybean [Glycine max (L.) Merr.] genotypes that are grown in solution cultures are highly sensitive to the combination of both salinity and inorganic phosphate (Pi) in the substrate. This effect has been observed on numerous occasions on plants grown in a saline medium that contained a substantial amount of Ca (i.e., CaCl₂/NaCl=0.5 on a molar basis). Because Ca is important in regulating ion transport and membrane permeability, solution culture experiments were designed to examine the effects of various concentrations of Pi and ratios of CaCl₂/NaCl (0 to 0.5 on a molar basis) at a constant osmotic potential (−0.34 MPa) on this adverse interaction. Four soybean cultivars (‘Lee’, ‘Lee 74’ ‘Clark’ and ‘Clark 63’) were tested. No adverse salinity x Pi interaction was found on Lee at any ratio and leaf P and Cl were maintained below 300 and 200 mmol kg⁻¹ dry wt, respectively. Clark, Clark 63 and Lee 74 soybean plants, on the other hand, were severely injured by solution salinity (−0.34 MPa osmotic potential) when substrate Pi was ≥0.12 mM. Reduced substrate Ca did not intensify the salinity x Pi interaction. On the contrary, the onset of injury was hastened and more severe with increased CaCl₂/NaCl ratios in isotonic solutions. Shoot and root growth rates decreased as injury increased. Leaf P concentrations from these cultivars grown in saline solutions with 0.12 mM Pi were excessive (>600 mmol kg⁻¹ dry wt) compared with concentrations commonly found in soybean leaf tissue yet they were independent of the severity of injury. Since leaf Cl increased wiht increased CaCl₂/NaCl ratio, we suspect that the severity of foliar injury was related to the combined effects of excessive P and Cl within the tissue. Lee 74, the only injured cultivar examined that excluded Cl from its leaves, was less sensitive than either Clark cultivar and its injury was characteristically different. Other ion interactions were reported that may have played a role in injury susceptibility.     

Transpiration and Calcium Deposition by Unifoliate Leaves of Phaseolus vulgaris Differing in Maturity

Unifoliate leaves were individually enclosed in clear, plastic chambers for the 24 hour treatment periods and then sacrificed for Ca analysis. Two transpiration rates were obtained by passing dry air through the chambers tising flow rates of 160 and 260 cm³/min. A third rate was obtained by a combination of shade and the lower air flow rate. Neither the transpiration rate nor solution-Ca concentration (0.5mM and 2.5 mM of 0.1, and 0.5 strength Hoagland solution) altered the amount of Ca deposited in the unifoliate leaves of 22 day old bean plants (Phaseolus vulgaris). The transpiration rate per unit area of leaf remained constant for all ages studied (1l–20 days) and was 1.8, 2.7, 3.6 g H₂O per dm² day for the three different imposed conditions. A definite pattern of Ca deposition occurred. With all the transpiration rates there was a maximum rate of calcium deposition at 13 days of growth and a gradual decrease thereafter. When the Ca concentration of the nutrient solution was 20 μg/ml the daily Ca deposition in terms of water transpired by the unifoliate leaves exceeded this amount, except for the oldest leaf tested, and, the maximum Ca to water ratios were 250, 320, and 430 (μg Ca/g) in order of decreasing transpiration rates. The uptake of Ca against a concentration gradient and approximately the same total uptake regardless of transpiration rates and solution concentrations used, firmly suggest that Ca secretion into root-xylem elements from a surrounding low level Ca solution requires energy expenditure by the plant. A possible explanation was proposed for the decreased rate of Ca deposition by the unifoliate leaves subsequent to the 13th day.     

Alleviation of salinity stress in broccoli using foliar urea or methyl-jasmonate: analysis of growth,gas exchange,and isotope composition

We studied the effects of foliar application of urea or methyl-jasmonate (MeJA) on the salinity tolerance of broccoli plants (Brassisca oleracea L. var. italica). Plant dry weight, leaf CO₂ assimilation, and root respiration were reduced significantly under moderate saline stress (40 mM NaCl) but application of either urea or MeJA maintained growth, gas exchange parameters, and leaf N–NO₃ ⁻ concentrations at values similar to those of non-salinized plants. Additionally, when these two foliar treatments were applied leaf Na⁺ concentration was reduced compared with control plants grown at 40 mM NaCl. However, at a higher salt concentration (120 mM NaCl), no effect of the foliar applications was found on these parameters. Salinity also decreased leaf δ¹⁵N but increased δ¹³C. Our study shows the feasibility of using foliar urea or MeJA to improve tolerance under moderate saline stress.     

Individuation in Sorghum bicolor: a self-organized process involved in physiological adaptation to salinity

In Sorghum bicolor, salt-adaptation was defined as the capacity of plants to grow at 300 m M NaCl (a lethal concentration) following a 3-week pre-treatment with 150 m M NaCl (a sublethal concentration). Large populations induced for salt-adaptation were analysed. Two modes of osmotic regulation (Na-includer and Na-excluder) were differentiated during induction of salt-adaptation, in spite of the genetic and environmental homogeneity. This variability was not related to any incapacity of the Na-includers to control accumulation of Na ⁺ ions in the shoot, because most of the pre-treated plants displayed a similar capacity of growth and control of Na ⁺ uptake after transfer to 300 m M NaCl. This unsuspected complexity of initially homogeneous populations points on the inadequacy of physiological studies focused on the ‘average individual’. Further analyses showed that variability was not directly related to micro-environmental variations. It is concluded that a process of individuation is caused by a third source of variability, which is the expression of a self-organizing process normally occurring during the transition phases in development. In constraining environments, this phenomenon of individuation includes adaptive modifications.     

Salinity effect on plant growth and leaf demography of the mangrove, Avicennia germinans L.

We assessed the effect of salinity on plant growth and leaf expansion rates, as well as the leaf life span and the dynamics of leaf production and mortality in seedlings of Avicennia germinans L. grown at 0, 170, 430, 680, and 940 mol m⁻³ NaCl. The relative growth rates (RGR) after 27 weeks reached a maximum (10.4 mg g⁻¹ d⁻¹) in 170 mol m⁻³ NaCl and decreased by 47 and 44% in plants grown at 680 and 940 mol m⁻³ NaCl. The relative leaf expansion rate (RLER) was maximal at 170 mol m⁻³ NaCl (120 cm m⁻² d⁻¹) and decreased by 57 and 52% in plants grown at 680 and 940 mol m⁻³ NaCl, respectively. In the same manner as RGR and RLER, the leaf production (P) and leaf death (D) decreased in 81 and 67% when salinity increased from 170 to 940 mol m⁻³ NaCl, respectively. Since the decrease in P with salinity was more pronounced than the decrease in D, the net accumulation of leaves per plant decreased with salinity. Additionally, an evident increase in annual mortality rates (λ) and death probability was observed with salinity. Leaf half-life (t _0.5) was 425 days in plants grown at 0 mol m⁻³ NaCl, and decreased to 75 days at 940 mol m⁻³ NaCl. Thus, increasing salinity caused an increase in mortality rate whereas production of new leaves and leaf longevity decreased and, finally, the leaf area was reduced.     

Alteration of Components of Leaf Water Potential and Water Content in Velvetleaf under the Effects of Long-Term Humidity Difference

Velvetleaf (Abutilon theophrasti Medik.) was grown in growth chambers set at 45 or 85% relative humidity at 30°C, CO₂ 350 microliters per liter and 1000 micromoles per square meter per second of photosynthetically active radiation. Soil water potential was maintained at −0.05 megapascal by subirrigation with half strength Hoagland solution. The third, fourth, and fifth leaves from the base of 21- and 25-day-old plants were used for pressure-volume measurements. Components of leaf water status including water potential (osmotic and potential associated with the apoplast), leaf water content (apoplasmic and symplasmic water), and elastic modulus of leaf tissue were determined. Results indicate: (a) persistent dry air generated leaves with lower water potential at a given relative water content than did humid air; (b) the higher total leaf water content in plants grown in dry air was related to an increase in apoplasmic water, whereas symplasmic water remained similar in both humidity treatments; (c) difference in leaf water potential between low and high humidity treatments was related to decreased potential associated with the apoplast but not to a change in cell wall elasticity.     

Analysis of salinity effects on basil leaf surface area, photosynthetic activity, and growth

Basil (Ocimum basilicum L.) seedlings were cultured on liquid medium in controlled conditions. Two varieties differing in leaf size were compared. When plants were 30?days old, the medium was supplemented with 50?mM NaCl. After 15?days of treatment, root, stem and leaf biomass, leaf number, and leaf surface area were measured. Ion accumulation was determined in roots, stems, and leaves. Photosynthetic parameters (CO₂ fixation rate, internal CO₂ concentration, stomatal conductance) as well as transpiration rate were determined on separate leaves. Electrolyte leakage and malondialdehyde content were used to estimate damage to membranes and lipid peroxidation, respectively. Several antioxidant enzymatic activities were used as proxies of oxidative stress. High Na⁺ concentration was reached in leaf tissues. Salt restricted whole plant biomass deposition rate by diminishing leaf number and leaf expansion, as well as photosynthetic activity were estimated from whole plant biomass production per unit leaf surface area. Diminished stomatal conductance restricted CO₂ fixation rate, and decrease in chlorophyll content presumably limited photosynthetic activity. Lipid peroxidation revealed damages to membranes. The magnitude of these responses differed between the two varieties, indicating that an intraspecific variability in salt response exists in basil.     

Humic acid differentially improves nitrate kinetics under low‐ and high‐affinity systems and alters the expression of plasma membrane H+‐ATPases and nitrate transporters in rice

Humic acids (HAs) have a major effect on nutrient uptake, metabolism, growth and development in plants. Here, we evaluated the effect of HA pretreatment applied with a nutrient solution on the uptake kinetics of nitrate nitrogen (N‐NO₃^?) and the metabolism of nitrogen (N) in rice under conditions of high and low NO₃^? supply. In addition, the kinetic parameters of NO₃^? uptake, N metabolites, and nitrate transporters (NRTs) and the plasma membrane (PM) H⁺‐ATPase gene expression were examined. The plants were grown in a growth chamber with modified Hoagland and Arnon solution until 21 days after germination (DAG), and they were then transferred to a solution without N for 48 h and then to another solution without N and with and without the addition of HAs for another 48 h. After this period of N deprivation, the plants received new nutrient solutions containing 0.2 and 2.0 mM N‐NO₃^?. Treatment of rice plants with HA promoted the induction of the genes OsNRT2.1‐2.2/OsNAR2.1 and some isoforms PM H⁺‐ATPase in roots. The application of HAs differentially modified the parameters of the uptake kinetics of NO₃^? under both concentrations. When grown with 0.2 mM NO₃^?, the plants pretreated with HA had lower K_m and C_min values as well as a higher V_max/K_m ratio. When grown with 2 mM NO₃^?, the plants pretreated with HA had a higher V_max value, a greater root and shoot mass, and a lower root/shoot ratio. The N fractions were also altered by pretreatment with HA, and a greater accumulation of NO₃^? and N‐amino was observed in the roots and shoots, respectively, of plants pretreated with HA. The results suggest that pretreatment with HA modifies root morphology and gene expression of PM H⁺‐ATPases and NO₃^? transporters, resulting in a greater efficiency of NO₃^? acquisition by high‐ and low‐affinity systems.     

Fluctuated water depth with high nutrient concentrations promote the invasiveness of Wedelia trilobata in Wetland

The distribution of invasive and native species in wetlands is determined by hydrological conditions; whereas conditions such as water depth fluctuations, variations in the nutrient concentrations are expected to affect the growth and physiological traits of plants. For the assessment of such effects, we conduct greenhouse experiment with three factors; 1) water depth of 5 cm and 15 cm (static and fluctuated); 2) three levels of nutrient concentrations (i) full‐strength Hoagland solution (N1), (ii) ¼‐strength Hoagland solution (N2), and (iii) ¹/₈‐strength Hoagland solution (N3); and 3) species, invasive Wedelia trilobata (L.) and its congener, native Wedelia chinensis (Osbeck.) under mono and mixed culture. Water depth of 5 cm combined with any of the nutrient treatments significantly restrained the photosynthesis, intracellular CO₂ concentration and leaf chlorophyll of both W. trilobata and W. chinensis. Increase in the water depth to 15 cm with low‐nutrient treatment N3 did not sustain the physiological traits of W. chinensis under mono and mixed planting. A great loss was noted in the growth of W. chinensis at 15 cm static and fluctuated water depth with low‐nutrient treatment (N3) and under mixed culture. In addition, water depth fluctuations with both low‐ and high‐nutrient treatments significantly affected the root‐shoot ratio, relative growth rate, and interspecific interaction among these two species. W. trilobata benefited more from competitive interaction index (CII) under fluctuated water depth at 15 cm with high nutrients, and the value of CII was clearly positive. Therefore, higher competitive ability may contribute to the invasiveness of W. trilobata in wetlands.