Faced with severe global shortage of water and soil resources, studies on the integrated effect of water and nitrogen on tomato cultivation are urgently needed for sustainable agriculture. Two successive greenhouse experiments with three irrigation regimes (1, 2/3, 1/3 full irrigation) and four nitrogen levels (1, 2/3, 1/3, 0 nitrogen) were conducted; plant growth, fruit yield and quality were surveyed; and comprehensive quality and net profit were evaluated. The results show that water and nitrogen deficit decreased plant growth, evapotranspiration and yield while increasing production efficiency and fruit comprehensive quality. An antagonism effect from water and nitrogen application was found in tomato yield, organic acid, solids acid ratio, vitamin C and lycopene, whereas synergistic impact was observed in total soluble solids content. Water deficit had more significant effect on tomato yield and fruit quality parameters compared with that of nitrogen deficiency. Synthesizing the perspectives of yield, quality, resource productivity, market price index and profits, 1/3 full irrigation and 2/3 full nitrogen was the best strategy and could be recommended to farmers as an effective guidance for tomato production.
In this paper, a new method for predicting wave overtopping discharges of Accropode armored breakwaters using the non-hydrostatic wave model Simulating WAves till SHore (SWASH) is presented. The apparent friction coefficient concept is proposed to allow the bottom shear stress term calculated in the momentum equation to reasonably represent the effect of comprehensive energy dissipation caused by the roughness and seepage during the wave overtopping process. A large number of wave overtopping cases are simulated with a calibrated SWASH model to determine the values of equivalent roughness coefficients so that the apparent friction coefficients can be estimated to achieve the conditions with good agreement between numerical overtopping discharges and those from the EurOtop neural network model. The relative crest freeboard and the wave steepness are found to be the two main factors affecting the equivalent roughness coefficient. A derived empirical formula for the estimation of an equivalent roughness coefficient is presented. The simulated overtopping discharges by the SWASH model using the values of the equivalent roughness coefficient estimated from the empirical formula are compared with the physical model test results. It is found that the mean error rate from the present model predictions is 0.24, which is slightly better than the mean error rate of 0.26 from the EurOtop neural network model.
Background: Rhamnus utilis Decne (Rhamnaceae) is an ecologically and economically important tree species. The growing market demands and recent anthropogenic impacts to R. utilis forests has negatively impacted its populations severely. However, little is known about the potential distribution of this species and environmental factors that affect habitat suitability for this species. By using 219 occurrence records along with 51 environmental factors, present and future suitable habitats were estimated for R. utilis using Maxent modeling; the important environmental factors affecting its distribution were analyzed. Results: January water vapor pressure, normalized difference vegetation index, mean diurnal range, and precipitation of the warmest quarter represented the critical factors explaining the environmental requirements of R. utilis. The potential habitat of R. utilis included most provinces from central to southeast China. Under the climate change scenario SSP 245, Maxent predicted a cumulative loss of ca. 0.73 × 105 km2 in suitable habitat for R. utilis during 2041–2060 while an increase of ca. 0.65 × 105 km2 occurred during 2081–2100. Furthermore, under this climate change scenario, the suitable habitat will geographically expand to higher elevations. Conclusions: The findings of our study provide a foundation for targeted conservation efforts and inform future research on R. utilis. By considering the identified environmental factors and anticipating the potential impacts of climate change, conservation strategies can be developed to preserve and restore suitable habitats for R. utilis. Protecting this species is not only crucial for maintaining biodiversity but also for sustaining the economic benefits associated with its ecological services.
Background: Understanding the reproductive biology of weeds is crucial for managing them effectively. Diplachne fusca (Poaceae) is a widely distributed weed species that poses significant challenges to agricultural productivity. Nevertheless, it remains unclear how the soil seed bank of D. fusca responds to environmental shifts, and whether a dormancy cycle is present in this species. Methods: We investigated how seed dormancy in D. fusca is broken and how it responds to natural environmental changes. The impact of incubation temperature, light exposure, cold stratification at 4 °C, and gibberellic acid (GA3) on seed germination/dormancy-break was investigated, along with assessing seasonal changes in germinability through monthly excavation and laboratory incubation of buried seeds over 2 years. Results: Results indicated that newly ripened seeds of D. fusca were dormant, with germination facilitated by GA3, cold stratification, and after-ripening at ambient room conditions. Exposure to darkness inhibited germination. Seasonal patterns of germination were observed, with peak germination occurring in cooler months and a marked decline during the hot summer months. After 2 years of being buried, approximately 40% of the seeds remained viable. Conclusion: In summary, seeds of D. fusca exhibit non-deep physiological dormancy and maintain a persistent soil seed bank. Seeds buried in the soil undergo a yearly dormancy/non-dormancy cycle. This dormancy cycle prevents seed germination and seedling emergence in autumn, which boosts the survival of seedlings in less favorable seasons, yet it also makes it more challenging to eradicate this weed.