Xerophytophysiology

The terminology “xerophytophysiology” is a compound word from “xerophyte” and “physiology”. “Xero” means dry or drought and “xerophyte” means drought adapted plant. “Xerophytophysiology” is referred to as the xerophytic physiology of common plants including not only xerophytes but also mesophytes and hydrophyte (Xu, 2007). Researchers have proposed the concept of and approaches to applications of xerophytophysiology to agronomical plant production with the theory of signal transduction adopted (Xu et al. 2009a,b,c,d). The xerophytophysiologyical applications include regulated deficit irrigation for soil-based crops such as partial root drying and infiltration or sub-irrigation, stimuli to hydroponic crops caused by substrate or root salinity with high electrical conductance in nutrient solution, and expositions of hypocotyl (peanut), mesocotyl (sorghum), bulb-cloves (garlic) and roots that would not be exposed in normal cases. In most cases, plants are hardened by placing the seedlings under artificial modest drought environmental stimuli such as soil or substrate water deficit, salinity, low himudity and high irradiation. Plants treated with these practices all benefit from the xerophytophysiological acclimations, with many processes inside plant changing in adaptation to the stimuli at the early stages. The stimuli are supposed to be perceived by the plants and the signaling messages are sent to the internals of the gene system, where the related genes are activated and expressed, leading to a series of physiological and morphological regulations. The processes include physiologically osmotic adjustment whereby the solutes concentration in cells, leaf turgor and the symplastic water fraction become higher than usual in the later growth stages, which are favorable for photosynthesis and matter production. Morphologically, the plant grows thicker and shorter with more wax and cuticle deposited on leaf surface immediately after the treatment and will grows stronger and larger when the stimuli are released. Both physiologically and morphologically, the plant becomes healthier than usual and consequently shows higher resistance to disease infection and the coming environmental stresses. In many cases, the stimulus is not necessarily a real or severe stress and it may only be a mild, partial or false stress.
References
Xu H.L. 2007. Xerophytophysiology in Crop Production. In: Xu H.L. (ed.) Dryland crop production -Technology breakthroughs and study cases. Research Signpost, Kerala, India, p. 37-54.
Xu H.L., Qin F.F., Wang J.S., Xu R.Y., Wang M.L. and Morita S. 2009a. Applications of xerophytophysiology in plant production - Peanut cultivation with the AnM method. Journal of Food, Agriculture and Environment (JFAE) 7:565-570.
Xu H.L., Qin F.F., Xu R.Y., Wang F.H. and Li F.M. 2009b. Applications of xerophytophysiology in plant production- Sorghum plants improved by exposing the mesocotyl as stimulus. JFAE 7:603-610.
Xu H.L., Qin F.F., Xu Q.C., Li F.M. and Du F.L. 2009c. Application of xerophytophysiology in plant production - Growing wheat on ridged bed. JFAE 7(3&4):000-000 (in press).
H.L., Qin F.F., Wang F.H. , Xu Q.C., Wang R., Shah S.K., Zhao A.H., Li F.M and Du F.L. 2009d. Applications of xerophytophyiology in plant production - Partial root drying improves tomato crops. JFAE 7(3&4):000-000 (in press).

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