Epiphytes and hemi-epiphytes are important floristic, structural and functional components of tropical rainforests. Their specific responses to light, temperature and water conditions during seed germination allow them to coexist with tropical forest trees. Here we investigated the effects of temperature, red to far-red light ratio (R:FR ratio) and water stress on seed germination of Ficus virens in tropical seasonal rainforest in Southwest China. We used incubators to create required temperature regimes, polyester filters to produce R:FR ratio gradients and mannitol solutions to simulate water stress. It was found that seed germination of F. virens was inhibited in the simulated understory conditions, i.e., at lower temperature (22/23°C), especially when combined with the R:FR ratio of 0.25, for which the germination percentage was less than 20%. In contrast, the seed germination percentages in the simulated canopy environment (22/32°C) showed no significant difference between R:FR ratios, with an average seed germination percentage as high as 65.8%. Seed germination delayed and decreased along with increasing water stress and was completely inhibited at -2.5 MPa, which might suggest that it is a kind of adaptation for F. virens seeds to detect the rainy season as germination chance on the canopy. Therefore, our study revealed the physiological mechanism for F. virensto be able to adapt to canopy environment.
In contrast to the rapid development of the horse husbandry in China, the ability of horse veterinarians to diagnose diseases has not been improved and only a few domain experts have considerable expertise. At present, many expert systems have been developed for diseases diagnosis, but few for horse diseases diagnosis have been studied in depth. This paper presents the design and development of a computer-aided expert system for diagnosing horse diseases. We suggest an approach for diagnosis of horse diseases based on the analysis of diagnostic characteristics and the experiential knowledge of domain experts. It is based on using evidence-weighted uncertainty reasoning theory, which is a combination of evidence theory and an uncertainty pass algorithm of confidence factors. It enables drawing of inferences with atypical clinical signs and the uncertainty of the user’s subjective understanding. It reduces the influence of subjective factors on diagnostic accuracy. The system utilizes a user friendly interface for users and requests a confidence factor from users when feedback is given to the system. Horse-Expert combines the confidence factors with weight factors assigned to clinical signs by experts during the knowledge acquisition process to make diagnostic conclusions. The system can diagnose 91 common horse diseases, and provides suggestions for appropriate treatment options. In addition, users can check the medical record through statistical charts. The system has been tested in seven demonstration areas of Xinjiang province in northwestern China. By constantly maintaining and updating the knowledge base, the system has potential application in veterinary practice.
Hydrogen sulfide (H₂S) has the ability to strengthen plant stress tolerance; however, the effects of H₂S on wheat seedlings under salt stress and the underlying molecular mechanism are still unclear. This study examined the effects of exogenous NaHS as H₂S donor on photosynthesis, antioxidant system, and the expression profile of genes related to antioxidant defense responses, the salt overly sensitive (SOS) and mitogen-activated protein kinase (MAPK) pathways in wheat seedlings treated with NaCl stress. H₂S application improved photosynthesis, and decreased H₂O₂ and malondialdehyde (MDA) contents in wheat seedling leaves under NaCl stress. In addition, antioxidant enzyme activity and the content of ascorbic acid and reduced glutathione increased with H₂S application. Moreover, H₂S pretreatment up-regulated expression levels of genes related to antioxidant system, SOS pathway and MAPK pathway as well as the transcription factor dehydration-responsive element binding gene. Overall, these findings suggest that H₂S alleviates salt stress in wheat seedlings not only by strengthening antioxidant defense systems, but by coordinating signal transduction pathways related to the stress response at a transcriptional level.