To evaluate the effects of different irrigation and nutrient concentration strategy on growth, yield, water use efficiency (WUE), fruit quality and substrate salt accumulation, tomatoes were grown with five different levels of water (W: 50%, 75%, 100%, 125% and 150%) and nutrient concentrations (N: 0.5, 0.75, 1.0, 1.5 and 2.0 times of Hoagland strength(X)). Fruit quality index was determined by normalization of fruit quality parameters. Deficit irrigation at standard concentration of nutrients reduced yields by 17.43% and 15.52% for T₇ (W_75%-N_1.0x) and 49.54%–51.99% for T₈ (W_50%-N_1.0x) during spring-summer (SS) and fall-winter (FW) seasons, respectively. Contents of total soluble solids (TSS), titrable acidity (TA) and sugar acid ratio (SAR) were all increased in water-deficit treatments. T₈ was found to be highest in TSS, TA and SAR except SAR in FW. Over-irrigation with excessive and standard Hoagland nutrient concentration caused non-significant reduction in yield except T₆ (W_125%-N_1.0x) in SS. T₂ (W_100%-N_2.0x) and T₄ (W_100%-N_1.5x) caused more substrate salt accumulation which resulted in significant decrease in yield and WUE. Through economic analysis, over-watering along with excessive nutrients caused profit reductions. Considering water saving, yield and fruit quality through economic analysis, T₇ found to be optimal strategy.

Plant invasions can affect soil properties in the invaded habitat by altering the biotic and abiotic nature of soils through positive or negative plant–soil feedback. Litter decomposition from many invasive species enhanced soil nutrients, thereby decreasing native plant diversity and leading to further plant invasions. Here, we examined the impact of litter decomposition from an invasive plant (Sphagneticola trilobata) in a range of soils at varying depths on growth and physiology of its native congener (Sphagneticola calendulacea). We added litter from S. trilobata to each soil type at different depths (0, 2, 4 and 6 cm). Plants of S. calendulacea were grown in each treatment, and morphological and physiological parameters were measured at the end of the growing period. All soils treated with litter displayed increases in soil nutrients at depths of 2 and 4 cm; while most growth traits, leaf chlorophyll and leaf nitrogen of S. calendulacea decreased at the same soil depths. Therefore, litter decomposition from invasive S. trilobata resulted in a positive plant–soil feedback for soil nutrients, and a negative plant–soil feedback for growth in native S. calendulacea. Our findings also suggest that the effects of litter decomposition from an invasive plant on soils and native species can vary significantly depending on the soil depth at which the litter is deposited. Future studies should focus on plant–soil feedback for more native and invasive species in invaded habitats, and the effects of invasive litter in more soil types and at greater soil depths.

Two cultivars of okra (Chinese green and Chinese red) were subjected to salt stress (0%, 6%, 12% and 18%) and equal proportions of NaCl and CaCl₂ in Hoagland’s nutrient solution and re-watering. Salt stress significantly reduced growth parameters and photosynthetic attributes of both cultivars. Treatment subjected to 18% salt stress caused 90% redundancy in growth parameters of both cultivars compared to control. Re-watering gave a positive response for plant growth of both cultivars in different levels. Chinese green showed better recovery at 6–0% re-watering level and Chinese red showed 12–6% and 6–0%, due to its salt tolerance nature. Considering re-watering water use efficiency and net photosynthetic rate the optimum values of salt tolerance for Chinese green and Chinese red were 8.3% and 12.02%, respectively. The best re-watering degree found as salt stress level ranged from 12.02% to 6% for Chinese red and 8.3% to 2.3% for Chinese green. This study provided a new method for the determination of irrigation time and quantification in crops.

Salinity is one of major environmental problem which is limiting the agricultural production. This research was conducted to evaluate the effect of re-watering on Brassica napus L., and determination of an appropriate regime for dilution of salted water by studying photosynthetic and growth response of B. napus to salt stress and subsequent re-watering. Plants were treated with NaCl (Nc₁: 2.5, Nc₂: 5, Nc₃: 10; g L^-1); Na₂SO₄ (Ns₁: 2.5, Ns₂: 5, Ns₃: 10; g L^-1) and mixed salts treatments (M₁: Nc₁+ Ns₃; M₂: Nc₃+ Ns₁; M₃: Nc₂+ Ns₂; g L^-1) and 0 as control, followed by re-watering. In salt stress phase, maximum reduction in net photosynthetic rate (P_N) was noted 79.54%, 80.72%, 84.54%, and 74.84% for Nc₃, Ns₃, M₁ and M₂, respectively, under high concentration levels. To maintain P_N, carbonic anhydrase (CA) activity was stimulated and kept water status stable under low (Nc₁ and Ns₁) to medium concentration levels (Nc₂, Ns₂ and M₃), and the decreases in P_N under Nc₂, Ns₂ and M₃ were 48.28%, 55.58% and 58.69%, respectively. However, during re-watering phase, growth and physiological parameters were recovered well due to regulation of CA activity under low to medium concentration levels. Relatively as compare to other stress levels more recovery in P_N was found after re-watering under medium concentration levels, which were 44.94%, 53.45% and 63.04%, respectively. Though aimed at consideration of high production in B. napus, the best re-watering time was found to be when plants undergo medium concentration levels. Therefore, this study provides a new method for dilution of saline irrigation based on plant physiology.

This research was conducted to determine the water consumption of tomato plants, the effects of water stress on stem sap flow (SF) and its response to climatic factors. SFs in 100% irrigation (T₁), 75% (T₂) and 50% (T₃) of irrigation amount of T₁ were monitored using Dynagage sensors. Compared to T₁, the difference in SF was observed under deficit irrigation in the same climatic conditions on sunny days although there was no apparent difference between T₁ and T₂ on cloudy days. Under T₁, the correlation and regression relationships between SF and climatic factors were analyzed at daytime (6:00–22:00), morning (6:00–14:00) and afternoon (14:00–22:00). Considering daytime, the order of sensitive indicators to SF was VPD > LI > Ta and LI > VPD > Ta for the Fall-Winter sunny days and Spring-Summer season, respectively. The water uptake over SFs measured for Fall-Winter and Spring-Summer periods were calculated as 168.65 and 229.18 mm, respectively.

Climate change and artificial disturbance may lead to increased submergence and eutrophication near a riparian zone and the shift of terrestrial plants into a riparian zone. In this study, the responses of terrestrial invasive Wedelia trilobata (WT) and congener native Wedelia chinensis (WC) plants were examined under submergence and eutrophication. A greenhouse experiment was conducted in which ramets of WT and WC were investigated under two levels of submergence (S1 and S2) and three levels of nutrients (N1, N2 and N3) along with two cultures (mono and mixed). Submergence (S) did not affect the morphological traits of both the species but nutrients (N), culture (C) and their interaction, along with submergence, had a significant effect on the morphological traits of both the species. The growth of WC under high submergence and high nutrients was decreased compared with low nutrients (N1, N2) but WT maintained its growth in monoculture. In mixed culture, low submergence (S1) and low nutrients (N1, N2) made WC more dominant but high submergence (S2) and high nutrients (N3) made WT more successful than WC due to its high phenotypic plasticity and negative effect of competition intensity. It was concluded that both species survive and grow well under submergence and eutrophication, but high submergence and eutrophication provide better conditions for WT to grow well.