| Due to uneven spatial and temporal distribution of precipitation and frequent occurrence of extreme dry weather in recent years, the drought had become the main restriction factor that can effect the development of agriculture and animal husbandry and vegetation restoration in the Karst rocky desertification Guizhou. And then the surface be reduced to fragments, unique two yuan structure, extremely easy infiltration of precipitation, low vegetation coverage and the surface water resources shortage, the use of difficulty and thin soil layer, poor water holding capacity of soil and water storage capacity magnified the loss caused by drought disasters more. While planting grass in Karst rocky desertification area can not only get the ecological benefit and prevent the rocky desertification occurrence and spread, but also can make the local people to obtain economic benefits. So studying on drought resistance of forage grass in Karst area screened out the drought resistance forage that was suitable for arid environment of Karst rocky desertification areas; studying on the drought resistance of forage planting technology can not only provide theoretical and technical support for the vegetation restoration in rocky desertification area and ecological environment restoration, can also reduce the economic loss caused by the drought disaster to agriculture and animal husbandry of the rocky desertification area.In this research, use the theory of stress physiology, biodiversity, biodiversity, sustainable development and circular economy as theoretical basis, do water-controlled drought stress physiology experiment of indoor potted plant in Wheat Genetics Research Institute of Guizhou Normal University and Key Laboratory of Plant Physiology in Guizhou Province in 2013, and combine with the field dry shed experimental method conducted in Bijie salaxi demonstration area to monitor the drought resistance of the 9 grasses under drought stress to screen out the strong drought resistance forage which was suitable for the large-scale cultivation in Karst rocky desertification area. And according to the situation which seasonal and engineering drought of Karst Desertification Area was serious, we developed 7 kinds of drought resistance and moisture set water grass planting technology. Meanwhile, select the typical representative potential-mild desertification control demonstration zone in Bijie Salaxi Karst Plateau Mountainous Region and moderate-intensity rocky desertification control demonstration zone in Huajiang Karst Plateau Gorge as the research object and according to the research and application of key support technology, we constructed a three-dimensional agricultural model based on drought resistant forage cultivation to carry out the field experiments and demonstrations. The main conclusions are as follows: 1. Response of physiological indexes of 9 kinds of grasses to drought stressIn Pot water control experiment, with the aggravation of drought stress, the chlorophyll content of 9 kinds of grass species showed a downward trend. Under severe drought stress, the decline scope of the chlorophyll content of Medicago sativa was the most, the decline scope of the chlorophyll content of Dactylis glomerata was least. With the aggravation of drought stress, the photosynthesis physiological index of different grass species had different changes, the net photosynthetic rate of 9 kinds of grass species decreased compared with the control group under severe drought. The highest value of all was Dactylis glomerata. Under severe drought stress, the transpiration rate of different grass species was that Trifolium linn seed was the highest, followed by the Festuca arundinacea.Under severe drought stress, the leaf relative water content of the grasses had reached the minimum value, the highest leaf water content of all was Trifolium pratense L; Festuca arundinacea; Trifolium linn. The order of the relative conductivity of grasses was that: Medicago sativa > Eragrostis pilosa > Panicum bisulcatum > Festuca arundinacea > Dactylis glomerata >Arthraxon hispidus > Trifolium linn > Trifolium pratense L > Medicago sativa. This showed that leaf cell membrane system of Medicago sativa and Trifolium pratense L had strong tolerance, strong drought resistance ability. However, the permeability of cell membrane system of the leaves of Medicago sativa and Eragrostis would suffer the biggest victim, so the membrane permeability was increased, drought resistance ability was weakened. The order of the content of MDA in leaves was that: Medicago sativa> Dactylis glomerata > Festuca arundinacea > Arthraxon hispidus > Eragrostis pilosa > Trifolium linn > Panicum bisulcatum > Trifolium pratense L > Medicago sativa. The order of the content of proline, from high to low, was that: Medicago sativa> Festuca arundinacea > Trifolium pratense L > Medicago sativa> Eragrostis pilosa > Dactylis glomerata > Arthraxon hispidus > Panicum bisulcatum > Trifolium linn.Above results suggest that when subjected to drought stress, photosynthetic and physiological indexes of various grass will appear different changes in trend and degree with different degree of drought stress. The specific changes in the extent and trend are related with drought stress degree which the plant suffered and the different plant species. The drought stress experiment of pot controlled water stress, physiological experiment and photosynthetic can be used as the experimental method to study the drought resistance of forage grass. 2. The comprehensive evaluation results of drought resistance of 9 kinds of grass species by the membership function methodUtilize the membership function(the anti membership function) for Photosynthetic Physiological Indexes and physiological and biochemical indexes of 9 kinds of grass species to undertake a comprehensive evaluation of drought resistance.The order of the drought resistance, from big to small, was that: Festuca arundinacea > Trifolium linn> Trifolium pratense L > Arthraxon hispidus > Dactylis glomerata > Medicago sativa> Eragrostis pilosa > Panicum bisulcatum > Medicago sativa. Compared to other grasses, Festuca arundinacea and Trifolium linn have a relatively strong comprehensive drought resistance. So Festuca arundinacea and Trifolium linn of severe drought areas can better adapt to drought and water shortage environment than other herbage, better to realize the local vegetation recovery, and also can reduce production cutting caused by drought. Therefore, Festuca arundinacea and Trifolium linn with high drought resistance have potential and necessary to promote large-scale cultivation in arid areas. 3. The validation results of forage grass drought resistance in the fieldIn order to select the excellent forage with strong drought resistance and high yield which was suitable for planting in the water shortage area of Rocky desertification, we developed the field drought test and verified the results of controlling water by potted planting experiment in Bijie Sa La Xi demonstration zone. The results showed that the net photosynthetic rate and WUE of the different seeds were that the Trifolium linn was the highest, Medicago sativa was the lowest; the Biomass of the different grass was the same as the net photosynthetic rate and WUE. The conclusions of water stress experiment of indoor pot controlled water are agree with the results of the field experiment. Water stress experiment of pot controlled water can be used as a kind of grass drought resistance screening method. Under drought stress, the drought resistance of Trifolium linn and Festuca arundinacea was best, production cutting was least. So in karst rocky desertification area, plant Trifolium linn and Festuca arundinacea can be better adapt to drought and water shortage environment, be more favorable for the restoration of vegetation in rocky desertification area, and the decrease of the yield is small when suffered the drought disaster. 4. Drought resistance and moisture set water grass planting technology suited for Karst Rocky Desertification AreaThrough the experiments and the monitoring of the indicators, through the comparative analysis treated with the control group, study the drought resistance soil water retention properties of traditional plastic mulch planting technology, fish scale pit planting technology, level trench planting technology, W type water collecting film, V type mulching and planting technology, planting technology of super absorbent polymers, and deep application of phosphorus fertilizer and potassium fertilizer technology and so on. Found that the moisture of soil moisture and drought water forage planting technology was better than those of the control group, of which the best technology of soil moisture and drought was traditional film covering technology, W type coated water harvesting techniques and water retaining agent planting techniques. However, due to the general karst rocky desertification region was based on mountain generally, and rocky desertification grades, soil thickness and slope of different regions existed bigger difference. So in the choice of fighting drought and preserving soil moisture collecting forage planting technology, we should select the most suitable technology according to different conditions. Generally, the smaller slope, no rocky desertification and slight rocky desertification area, as the thick soil layer, were suitabled for application of W film technology and traditional film technology to plant forage. In the middle slope and the moderate rocky desertification area, because of the thin soil, forage planting was suitabled for the use of planting technology of water retaining agent and applying phosphate fertilizer, potash fertilizer during the cultivation and growth period. The larger slope area and severe rocky desertification area can be used the technology of addition of phosphorus fertilizer, potassium fertilizer after using no tillage and grass planting technology and borrowed the engineering measures to build fish scale pit, which can keep water and prevent water and soil loss. 5. The construction of grass planting mode suited for Karst Rocky Desertification AreaCombined with the actual situation, the study found that potential-mild rocky comprehensive treatment demonstration area of Bijie Sarah Creek Karst Plateau Mountain was suitable to develop the stereo ecological agriculture mode which was "Pit- Joe(Walnut)- Irrigation(Rosa roxburghii Tratt)- grass(Dactylis glomerata, Medicago sativa mixed cropping)- cattle(sheep)- earthworm – chicken- biogas- fertilizer". The model combined with the stereoscopic layered agricultural of Joe Irrigation grass, can use light, heat, water, soil effectively and was the efficient use of system meeting the ecological chain. The model can not only be demonstration and utilization in Bijie Sarah Creek demonstration zone, but also can make appropriate improvements combined with other rocky desertification region and make extension in the vast potential-light rocky desertification control area.Combined with geographical features and rocky desertification of moderate-intensity rocky desertification control demonstration zone in the Huajiang plateau Gorge, the study found that the local was suitable for the development of "cellar- pitaya- legumes- sheep(cattle)- chicken biogas fertilizer" stereo ecological agriculture mode, which not only can utilize the light, water, soil effectively, but also obtain higher land output.Take the different geographical conditions and the degrees of rocky desertification into consideration to construct the most suitable governance model in rocky desertification area. We should take both the economic benefits and the ecological benefits into account in the planning process, and the process should comply with the energy operation of the ecosystem. Thus, the pattern can achieve efficient operation and can be promoted, improved and used in the same conditions of the rocky desertification area. 6. Benefit evaluation of planting drought resistance of forage grass in Karst Rocky Desertification AreaMonitor and calculate the plant diversity index, the species richness index, the evenness index and the soil physicochemical properties by using the method of plant samples at different land use form, found that land use form of the highest species richness was artificial mixed sowing grassland farming and the Simpson diversity index, the Shannon-Wiener index and the Pielou index of artificial mixed sowing grassland farming was higher. Drought resistance mixed artificial grassland in the content of organic matter, total nitrogen, total phosphorus content were higher than those of Qiao Guanlin, shrub forest and farmland, the total potassium content was lower than farmland, the soil capacity of the artificial grassland was only lower than of Qiao Guanlin, the soil field,s water holding capacity of the artificial grassland was just lower than of cultivated land and the soil porosity of the the artificial grassland was the lowest.To sum up, in Karst rocky desertification area, planting drought resistance mixed artificial grassland can not only enrich the local biodiversity, but also can effectively improve soil physical and chemical properties of the rocky desertification area. Therefore, it can obtain good economic benefits and get more ecological benefits than other land use patterns that planting drought resistant artificial mixed grassland widely in the rocky desertification area. |
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