| Stockbreeding is one of the traditional dominant industries on Loess Plateau, and it is also the foundation to develop the country economy in Northwest China. In arid and semi-arid area such as the loess hilly-gully region, one of the material bases for the animal husbandry-the artificial grassland construction is quite weak. Besides drought and the social and economic factors, lack understanding of the eco-adaptability of grasses to the environment is one of the most important reasons. It is meaningful for agricultural framework regulation and plants layout in vegetation construction through comparing or contrasting the productivity and eco-adaptability among grasses, and with crops and shrubs in the area, to know which one is the most adaptive and what is most suitable condition for the grasses.The representational grasses species, which are the pulse family plants such as Astragalus adsurgens, Sainfoin (Onobrychis viciaefolia Scop.) and alfalfa (Medicago saliva), smooth brome grass (Bromus inermis) as the grass family, the native plants Lespedeza davurica and Old World bluestems (Bothriochloa ischaemum), which belong to he pulse and grass family respectively; and the introduced grass switchgrass (Panicum viegatum) were chosen, the seeds emergence and seedling growth and water use characteristics were compared in different water level, also their productivities and water use were compared with the shrubs Cargana korshinskii and seabuckthorn (Hippophae rhamnoides) and the crop foxtail millet(Setaria italica) in the field, the main results are as follows:1 The pulse plants' seeds emergent faster than grasses; the drought tolerance order of seed emergence is foxtail millet>C. korshinskii>Melilotus a/6us>switchgrass (P. viegatum); the cumulative water that C. korshinskii seed absorbed decreases as the stress increases.2 Comparing the seedling root and aboveground growth and water use characteristics of alfalfa and A. adsurgens sole-cropped, switchgrass and B. ischaemum sole-cropped, the inter-copped alfalfa/B, ischaemum and switchgrass/ A. adsurgens in the growth chamber with one another under different water level treatments which are high water level(HW) (80%FC-14.72%) and drying from that, low water level (LWX50%FC-9.2%)and drying from that and then rewatered.2.1 Soil water kept stable: Alfalfa sole-cropped grows faster and has better WUEB (biomass dry weight water use efficiency) planted in HW than other treatments, the biomass and WUEB of A. adsurgens sole-cropped decrease less than alfalfa under LW as to HW, that'salso to B. ischaemwn than switchgrass; the WUEB of alfalfa and B. ischaemum inter-cropped under HW or LW is corresponded to alfalfa sole-cropped but can improve the latter's WUEL (leaf water use efficiency), switchgrass/A. adsurgens has bigger WUEB than each sole-cropped under LW.2.2 Soil drying: The pulse plants' soil water decreases more quickly than grasses when the irrigation ceased; when soil drying from the HW treatment, the threshold value of leaf potential drops steeply where the soil water content of alfalfa is the least means alfalfa is the most drought tolerant specie among them; the cause of photosynthetic rate (Pn) decrease from the HW is stomotal limitation, and that from the LW is non-stomotal limitation; the root/shoot increase extent of the pulse plants are bigger than the grass after the irrigation is ceased.2.3 Foxtail millet has the biggest WUEB under all treatments which mainly dues to its lowest stomotal conductance; only the grass family plants have compensation effects of biomass and WUEB after soil drying from LW and then rewatered; swithgrass seedling growth has some characteristics similar to the pulse plant such as high transpiration rate (Tr) and bigger root/shoot ratio.2.4 The switchgrass/ A. adsurgens inter-cropped has better adaptability to the soil water changes such as under LW or during soil drying comparing to HW than alfalfa/5, ischaemum.3 The productivity and soil water use of different plants were determined during 2001-20...
|
PDF Full Text Request