جستجوی مقالات مرتبط با کلیدواژه « فتوسنتز » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

This is the second of series on the impact of dust. It focuses on the physical, chemical and physiological effects of dust particles and aerosols. Plants of all types and classes (from algae to forest trees and everything in between) are adversely affected either directly through abrasion by airborne particles or through interference with plant physiology or indirectly through the impact on soil as particles are deposited in the soil surface with effects on the soil chemistry, soil texture and soil structure. The literature that is reviewed spans decades and the biomes from which examples are drawn cover regions from the Arctic Circle to the equator, from deserts to tropical rainforests. The physiological responses of plants underlie and precede ecological changes at the community level and these changes have implications for such important relationships as predator-prey as shelter food supply and other essential ecosystem services either cease to be provided or are severely curtailed. It was found that all species have maximum dust deposition in the winter season followed by summer and rainy seasons. Chlorophyll content decreased and ascorbic acid content increased with the increase of dust deposition. There was significant negative and positive correlation between dust deposition and chlorophyll and ascorbic acid content, respectively.

Salinity is one of major stresses which can severely limit plant production, especially in the arid and semi-arid regions. The present study was carried out to evaluate the impact of salinity stress on some physio-biochemical parameters in nitre bush plants (Nitraria schoberi). Thus, an experiment was carried out under natural conditions and salinity stress was induced by a combination of different salts (NaCl, MgCl2 and CaCl2) at four levels. The salinity treatments were: Control (Ctrl), Low Salinity (LS), Medium Salinity (MS) and High Salinity (HS) of the combined salts. In this study, photosynthetic apparatus of N. schoberi was damaged to a certain extent as it has been observed from leaf chlorophyll fluorescence parameters (Chl. FPs) such as minimal fluorescence (F0), maximal fluorescence (Fm) and maximal photochemical efficiency (Fv / Fm). A significant alteration in chlorophyll content of leaf was not noticed with the increased soil salt content up MS and thereafter, it significantly declined at HS. The reduced level of total chlorophyll content under salt stress conditions can be attributed to chloroplastid membrane deterioration leading to lesser accumulation of chlorophyll. The amount of inorganic ions in nitre bush plant leaves altered with an increase in salinity stress. The concentration of Na and Cl- steadily increased and on the contrary, the concentrations of K, Ca2 and Mg showed significant decreases only at HS. This phenomenon is explainable by the inhibition of K uptake by high Na levels because these cations are transported by the same proteins. In our experiments, we did not observe significant differences between control plants and those grown in presence of 300 mMol salt kg-1 dry soil (DS). Thus, nitre bush is considered to be a salt tolerant species.