Effects Of Chilling And Drought Stress On Physiological Characters Of Parahemionitis Cordata

Parahemionitis cordata(Roxburgh ex Hooker & Greville) Fraser-Jenkins, a tropical ferns which with well commercial prospects for its pharmaceutical,bio-pesticide and horticulture worth. The research about P. cordata cultivation and its stress-resistant physiology had not been reported.In this paper,the trophophyll and sporophyll of P. cordata were chosen as materials. By analysis the physiological character of P. cordata leafs under 5 chilling ℃injury stress,natural drought stress and in sporophyll developing process,the resistant capacity of P. cordata againist chilling injury and nature drought stress were studied,of which stress would usually be suffered during their horticulture and commercial cultivating;research about sporophyll developing is also help to study the physiological changes in sporophyll of dimorphous ferns. The result showed that:(1) Under the 5 chilling injury stress and natural drought stress℃,water deficit occurred. In both the trophophyll and sporophyll: electric conductance and MDA contents were increasing; SOD, POD and CAT activity were increasing; osmotic adjustment substances, including soluble sugar,soluble protein and proline contents were increasing. 5 ℃chilling stress influenced little about P. cordata chlorophyll. Net photosynthetic rate and transpiration rate declined with the decreased stomatal conductance and intercellular CO2 contents. Morphological characters of the chilling stressed trophophyll and sporophyll did not alternated, it was wilting in the drought stressed trophophyll and sporophyll in 8d, and the trophophyll recovery after rehydration, while the sporophyll didn’t. It suggested that both the trophophyll and sporophyll could certain resist chilling and drought stress from modulating their protective enzymes, osmotic adjustment and stoma,the resistant capacity is more pronounced in trophpphyll than in sporophyll. The chilling and drought stress impact reproductive organ more than nutritive organ.(2)During the developing of sporophyll,SOD activity,CAT activity,soluble sugar contents,soluble protein contents and proline contents were increasing; POD activity and chlorophyll contents changed little;Net photosynthetic rate and transpiration rate were increasing with the increased stomatal conductance and intercellular CO2 contents. After the spores releasing,POD activity and chlorophyll contents changed little,other indexes were decreasing. It suggested that physiological function in sporophyll is improved during developing period; it got climax once the spores matured. After the spores released, the sporophyll coming to senescence period, physiological functions start to decline.