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Based on runoff and meteorology observation data of Xilinhe River, the characteristics and variations of runoff and climate in the basin were examined by M-K trend analysis and double mass curve method. The results showed that the runoff in Xilinhe River Basin in recent 50 years slightly reduced (P>0.05), while runoff significantly decreased (P<0.05) from 1958 to 1990. After 1990s, annual runoff was significantly higher than that in the early period. At the beginning of 21th century, runoff significantly declined (P<0.05). Seasonal variations of runoff presented the bimodal runoff process which was specific in the midlatitude semiarid areas and formed by snowmelt and precipitation, respectively. There was an evidence suggested that Xilinhe River Basin was turning to dry and warm during these 50 years with reducing precipitation and increasing temperature. In most seasons, evaporation increased and precipitation decreased especially from July to September during recent five decades. These observations suggested that dry and warm climate was one of the important factors that changed the timing and quantity of the runoff. The change of precipitation in flood season had a leading role and the ice and snow melting in warming winter had a supporting role to the change of river basin runoff. Runoff coefficient declined since the 1960s and reached to the lowest during the 1980s, which suggested that the less runoff was produced by the same rainfall. The runoff coefficient increased in the 1990s and decreased again at the beginning of 21th century. The double cumulative curve showed that compared with the 1960s, the accumulated value of runoff had significant deviation since the 1970s, especially after the 1980s which indicated that the runoff in the basin was not only impacted by precipitation, but also affected by human activities. The dry and warm climate and increasing human activity were the main reasons of the water cycle change in the Xilinhe River Basin.
The variations of plant-soil system nitrogen storage in typical degraded steppe were measured in Xilin Hot City, Inner Mongolia. The values of plant-soil system nitrogen storage in different degraded grassland were also verified using DNDC(Denitrification-Decomposition) model. The results showed that soil nitrogen storage significantly reduced (PMD>LD. The nitrogen storage in roots gradually increased in the growing season and performed with the same order at the end of the growing season which was HD>MD>LD. The proportion of soil nitrogen storage in plant-soil system which ranged from 95.05% to 97.62% was higher than that of roots and plants nitrogen storage in plant-soil system. All of these results suggested that the DNDC model can accurately simulate the soil nitrogen storage in site in typical steppe.
The present study was to investigate the effects of grazing intensity on soil organic matter, pH, total nitrogen, available nitrogen, total phosphorus, available phosphorus, total potassium, and available potassium in soil of Kobresia pygmaea meadow community of Tibet plateau. The results showed that the contents of soil total nitrogen, available nitrogen and available potassium decreased, while the contents of total potassium increased firstly and then decreased with the increasing of grazing intensity. Heavy grazing intensity significantly reduced the contents of total nitrogen, available nitrogen, available potassium and available phosphorus(P0.05). The results suggested that delayed grazing with moderate grazing intensity could protect grassland from degeneration.
The legume-grass mixtures included three legumes (Onobrychis viciaefolia, Medicago sativa, Trifolium pretense) and three grasses (Dactylis glomerata, Bromus inermis, Phleum pretense). The mixed combinations were 6, 5, 4, 3 species mixture at three sowing ratios of legume∶grass with 5∶5, 4∶6, 3∶7, respectively. The experiment was conducted in Zhaosu Basin of Xinjiang with the randomized complete block design. The soil organic matter, total nitrogen(N), alkaline hydrolysis nitrogen, total phosphorus (P), available phosphorus, total potassium and available potassium were measured for analyzing the influence of mixed species and ratios of legume and grass on soil nutrients distribution and accumulation. The results showed that soils with the legume-grass mixtures had higher soil alkaline hydrolysis N content than soils with grass monoculture. And soils with the legume-grass mixtures had higher soil available P content than soils with grass and legume monoculture. The soil organic matter, alkaline hydrolysis N, total P and available P content decreased with the mixed ratios of legume and grass decreasing. The soil organic matter, total N, available P and total K content in soils with 3 and 4 species mixtures were higher than those in soils with 5 and 6 species mixtures whereas the soil alkaline hydrolysis N and available K content in soils with 3 and 4 species mixtures were lower than those in soils with 5 and 6 species mixtures. The two-way variance analysis indicated that the mixed species, interaction of mixed species and ratios of legume and grass were the main factors which influenced the variance of soil nutrients distribution and accumulation. The mixed ratios of legume and grass could significantly influence the variance of soil total P and K. Therefore, the legume-grass mixtures could improve the content of soil alkaline hydrolysis N and available P. The soil nutrients did not significantly increase with the increasing of legume ratios.
Agriculture protective forest is an important part of the protective forest system in the Jingtai electrical irrigation area. In order to provide technology support for renewal and reform of agriculture protective forest, the optimized model was proposed according to the analysis of present situation and degradation reasons. The result showed the agriculture protective forest predominated by Populus seriously declined, especially in terms of personal management areas which were incomplete or totally disappeared. The main reasons for these declines included the pests and diseases damage, cutting down because of serious water consumption and soil threat, poor growth and death because of serious farmland secondary salinization, single tree species and unreasonable structure, insufficient management. The renewal and reform of agriculture protective forest was necessary and feasible through employed excellent species, such as Populus tomentosa, P. langfangensis, Pinus sylvestris, Robinia pseucdoacacia, Fraxinus chinensis，Jujube minshan with rotation with dominant species of Populus and optimal modification of evergreen needle tree species. These optimization will have important influences on the improvement of the protective forest ecosystem and guarantee safety of Jintai oasis
Adonis amurensis is one kind of spring ephemeral perennial plant in northeast China and it is also one kind of excellent ornamental garden germplasm resource. A field investigation, including continuous observation, pollen/ovule rate (P/O) and fruit set rate, was conducted to study flower structure, flowering dynamic change and reproductive system of A. amurensis. The results showed that the population flower bloomed one time a year from March to April. The flower was large and the life span of individual flower were 6~10 days. Floral syndrome could attract pollinators. During the flowering phase, the pistil matured before stamens. At the same time, there were no space interval between stigma and anthers. The outcrossing index was 3 and the value of P/O was about 2 280. Combined these results with the results of bagging experiment, the reproductive system of A. amurensis could be determined as facultative outcrossing, self-compatible and pollinators depended.
The response of 15 warmseason turfgrass germplasm to longterm submergence stress or waterlogging stress was studied. The results showed that the waterlogging stress promoted the growth of Paspalum distichum P018and P019, Pa. vaginatum P021 and Pseudoraphis spinescens PX02, but significantly inhibited the growth of species such as Cynodon dactylonC. transadlensis C807 and C. dactylon C134. Based on the comprehensive analysis of the 15 germplasms, the ability of waterlogging tolerance was Pa. distichum P018Pa. distichum P019Pa. vaginatum P021Ps. spinescens PX02Pa. distichum P020Eremochloa ophiuroides E194C. dactylon C. transadlensis C751C. dactylon C291Pa. vaginatum P006C. dactylon C106E. ophiuroides E193C. dactylon C. transadlensis C807=C. dactylon C852C. dactylon C851C. dactylon C134. The 15 turfgrasses suffered significantly injury under submergence situation than those living in waterlogging situation, especially for two E. ophiuroides cultivars which cannot survive. Submergence tolerance decreased in the following order according to the analysis of subordinate function: Pa. distichum P018 Pa. distichum P019 Ps. spinescens PX02 Pa. distichum P020C. dactylon C291 C. dactylon C. transadlensis C751 C. dactylon C. transadlensis C807Pa. vaginatum P006 C. dactylon C852 C. dactylon C851 Pa. vaginatum P021 C. dactylon C106 C. dactylon C134 E. ophiuroides E194 =E. ophiuroides E193. Among all these 15 warm-season turfgrasses, Pa. distichum P018, Pa. distichum P019 and Ps. spinescens PX02 had strong resistance to both waterlogging stress and submergence stress which were suggested for vegetation reconstruction in natural riparian zone. Key words: warm season turfgrass; submergence stress; waterlogging stress
The Loess Plateau is the one of the most vulnerable areas of ecological environment, mainly characteried by serious soil erosion in China, which restrict the economic development of the region and the improvement of living standard. Therefore, it is very important to govern the ecological environment of Loess Plateau. This paper mainly analyzes and discusses three aspects of Loess Plateau, which include the particularity of geomorphology, topography, climate and soil. Simultaneously, we summarize the relevant measures of ecological restoration combining the current status of Loess Plateau deterioration and analyzing the reasons which result in the deterioration. Finally, we present some suggestions for the problems which mainly relate to the ecological restoration of Loess Plateau in recently relevant researches so as to provide some guidances for ecological environment comprehensive management of the Loess Plateau in future.
In order to reveal the genetic diversity of alfalfa germplasm resources, the genetic diversity of one wild and 41 cultivated alfalfa accessions were analyzed using SSR markers. The results showed that there were totally 231 alleles and 163 polymorphic alleles generated from these 42 alfalfa accessions by 15 SSR primers. The mean values of polymorphic percentage, Nei’s gene diversity and shannon’s information index for these 15 primer pairs were 71.55%, 0.210 0 and 0.326 3, respectively. The similarity coefficient of accessions ranged from 0.641 to 0.913 with an average of 0.791, and the mean value of similarity coefficient between wild alfalfa accessions and cultivars was lower than that among cultivars. Cluster analysis classified accessions into five defined groups at the genetic similarity value of 0.778, among which Longdong wild alfalfa, CW 200 and CW 787 were clustered into three independent groups, indicating that these accessions had relatively distant genetic relationship with the others. According to principal component analysis, the accessions can be divided into four groups, and the accessions in the Ⅰ and the Ⅱ groups had relatively distant genetic relationship with those in the Ⅲ and the Ⅳ groups. In conclusion, the alfalfa accessions used in the present study had relatively high genetic diversity, and some of which had relatively independent genetic characteristics.
Late embryogenesis abundant (LEA) family proteins are expressed abundantly at the late stage of embryonic development of plant seeds, and play important roles in responding to various environmental stress, such as drought, low temperature and high salinity. At present, the phylogenetic studies of LEA gene family in Medicago truncatula have not been reported yet. In this study, with the application of bioinformatics methods, the LEA family genes of M. truncatula were identified through the whole genome, and the system evolution, gene structure, evolutionary pressure, chromosomal location and gene expression patterns were further analyzed. A total of 23 LEA genes were systematically identified from M. truncatula and classified into 8 subfamilies. Gene location results showed that these 23 LEA genes were distributed unevenly on 7 chromosomes; The exon numbers of all the genes were no more than two, indicating a simple gene structure of this gene family. The expression profiles of M. truncatula LEA genes showed a characteristic of temporal and tissue specific, and regulated by drought stress. This study provides a theoretical foundation for verifying the function of LEA genes in M. truncatula.
The response of photosystem Ⅱ activity in leaves of Sorghum sudanense and S. bicolor×S. sudanense to drought stress was investigated by the fast chlorophyll fluorescence induction dynamics analysis. The results showed that the maximum photochemical efficiency (Fv/Fm) and the performance of PSⅡ activity (PIABS) in these two species decreased with the increasing intensity of drought stress, especially the PIABS reduction was significantly greater than Fv/Fm. Although the PSⅡ photochemical activity in leaves of both of these two species seedlings decreased under drought stress, the PSⅡ photochemical activity in S. bicolor×S. sudanense seedling leaves was significantly higher (P<0.05) than that in S. sudanense seedling. The possible reasons for these difference included that the rates of relative variable fluorescence increase at 0.15 and 0.3 ms on the OJIP curve of S. bicolor×S. sudanense seedlings were significantly less than that of S. sudanense seedlings under drought stress and that the impacts of drought on the complex activities of electron donor side OCE oxygen and thylakoid aggregation state in S. bicolor×S. sudanense seedlings was significantly less than those in S. sudanense seedlings which was important for the supply, transport and stability of electron in electron transport chain. In addition, the relative variable fluorescence of VJ and VI at 2 and 30 ms on the OJIP curve (J point and I point) of these two species forage seedlings significantly increased under drought stress suggested that the decrease of PSⅡ photochemical activity was correlated with the block of QA to QB transport in PSⅡ electron acceptor side and the decrease of the PQ library capability of accepting electron. However, there was significant difference between VJ and no significant difference between VI of S. bicolor×S. sudanense and S. sudanense leaves, indicating that the electron transfer body QB ability to accept electrons and the ability of transmitting electron of PSⅡ donor side of S. bicolor×S. sudanense seedlings were higher than those in S. sudanense under drought stress.
In order to analyze the tolerance of imported Rumex (Rumex patientia × R. tianschanicus cv. Rumex) to salt stress, the germination rate and seedling physiological characteristics of Rumex grown in media with NaCl were studied. The imported Rumex from Ukraine was marked as Material 1, and the native one as control was marked as Material 2. The performance of Material 1 and Material 2 were measured under different concentrations of NaCl (0, 50, 100, 150, 200, 250 and 300 mmol·L-1). The results showed that the germination rate of Material 1 was significantly higher than that of Material 2 (P<0.05) after 7 days growth in stress. Furthermore, after being treated with 150 mmol·L-1 NaCl for 7, 9, 11, 13 and 15 d, the superoxide dismutase, peroxidase and catalase activities in Material 1 were significantly higher than those in Material 2 (P<0.05) whereas the MDA content in Material 1 was significantly lower than that in Material 2 (P<0.05). These results suggested that Material 1, the imported Rumex from Russia, had a higher salt tolerance than Material 2. Material 1 was an excellent breeding material for saline soil.
Setaria sphacelata cv. Narok is one of the most prominent forages applied in grassland construction and environmental treatment in southern China, which has broad promotion prospects. However, the low seed yield, poor quality and deep dormancy restrict the popularization and utilization of this forage. Soaking treatment with exogenous hormones including GA3, IBA, 6-KT and ETH were applied to break dormancy of Narok seeds from Yunnan Province. The results showed that all of these four different exogenous hormones could break Narok seed dormancy and promote seed germination and seedlings growth with different effects. The treatment with 400 mg·L-1 GA3 soaking for 24 h was the best. The germination energy, germination percentage, germination index and the vigor index was 48%, 54%, 19.46 and 0.015 2, respectively, and increased by 1.18 times, 1.08 times, 1.31 times and 1.14 times compared with the control, respectively. These indices were significantly higher (P＜0.05) than the corresponding indices from control. Effects of the treatment with 450 μL·L-1 ETH soaking for 24 h was the second best. The treatments with 20 mg·L-1 IBA and 5 mg·L-1 6-KT soaking for 24 h also had significant promoting effects (P＜0.05) on Narok seeds germination.
Alfalfa (Medicago sativa) and wheat (Triticum aestivum) seeds were treated with different concentrations of aqueous extracts from Gentiana stramine leaves and roots. The results showed that the inhibition effects of aqueous extracts on seed germination and seedling growth of alfalfa and wheat gradually increased with the increase of the G. straminea plant aqueous extract concentration. Only with low concentrations (0.025 g·mL-1) G. straminea plant aqueous extracts promoted seed germination and seedling growth of alfalfa. The seeds germination of alfalfa were significantly inhibited (P<0.05) at a concentration of 0.1 g·mL-1. The inhibition effects on alfalfa was more serious than that on wheat. Inhibition effects of G. straminea aqueous extracts from leaves was significantly greater than root. The antioxidant enzyme activities of alfalfa and wheat were also affected by aqueous extract. Superoxide dismutase, peroxidase and catalase activities and malondialdehyde content significantly increased (P<0.05)with increasing concentrations.
In order to select the optimum 60Co-γ radiation dose to improve salt-tolerance of Glycyrrhiza uralensis, the present study explored the effects of 60Co-γ radiation on seed germination, accumulated germination percentage and germination index of G. uralensis under different Na2SO4 stress treatments. The results showed that seed germination percentage and germination index decreased and germination time delayed with the increase of salt concentration. However, seed germination percentage of G. uralensis exposed to 60Co-γ radiation and then treated with high Na2SO4 stress was significantly higher than that of control， which indicated that 60Co-γ radiation could effectively improve seed germination percentage under Na2SO4 treatments. These results suggested that different 60Co-γ rays radiation should be employed based on the concentration of Na2SO4 in soil. Especially, seeds of G. uralensis exposed to the 100 Gy radiation treatment showed higher tolerance to Na2SO4 stress.
In order to clarify the effects of the winter stratification on seed germination of alpine meadow plants, we studied the seed germination characteristics of 5 kinds of alpine meadow plants which were stratificated in Tianzhu alpine meadow soil, Tibetan sheep dung and yak dung, respectively, with the seeds stored indoor as the control. The results showed that the stratification influenced the germination percentage, initial germination days and germination index of Kobresia humilis, Blysmus sinocompressus, Iris tenuifolia, Carex enervis and K. capillifolia seeds which varied with the integrity of the seed coat, stratification matrix and grass species. Compared with the control, the winter stratification improved the scarified seed germination percentage and the germination index and reduced initial germination days of K. humilis, B. sinocompressus, I. tenuifolia, C. enervis and K. capillifolia. The influence of winter stratification on the seed germination of complete seed was lower than that on the scarified seed. The germination percentage of the scarified seed of B. sinocompressus stratificated in yak dung was significantly higher (P<0.05) than that in the Tibetan sheep dung and soil treatment. For the germination of the scarified seeds of K. humilis, I. tenuifolia and C. enervis, there was no significant difference between the different treatments of stratification matrix. There was no significant effect of winter stratification on the germination of the complete and the scarified seed of K. capillifolia.
In order to establish the management strategies for high grains yields of naked oat (Avena sativa) in Chengdu Plain, three naked oat cultivars Yanxuan 1, Bayou 6 and Baiyan 11 were used as materials to explore the effects of sowing date, sowing rate and fertilizer rate on the grains yields and agronomic characteristics of naked oat. The results showed the indices including number of productive ear, plant height, growing period and grains yield with the treatment sowing on 1st November (B1) were significantly (P0.05). Maximum yields occurred intermediate rate of sowing (3.60×106 plants·ha-1). The number of productive ear, plant height and grains yield increased with the increase of fertilizer rate (Psowing date>cultivar>sowing rate. Comparing the general score of Principal Components Analysis with the yield of each treatment, the sowing on 1st November was better than sowing on 12th November in oat grains yield. High sowing rate (1.80×106 plant·ha-1, 2.70×106 plant·ha-1 and 3.60×106 plant·ha-1) or high fertilizer rate (600 and 825 kg·ha-1) produced high yield. In general, early sowing (1st November ) with 1.80×106 plant·ha-1 sowing rate and 600 kg·ha-1 fertilizer rate were the best combination for grain yield of naked oat in Chengdu Plain.
Influences of different nitrogen application rates (N1:0 kg·ha-1, N2:100 kg·ha-1, N3:200 kg·ha-1, N4:400 kg·ha-1) on yield and forage quality of grain-forage maize which were planted in furrows of completely mulched in rainfed agriculture regions in the Loess plateau were investigated. The results showed that leaf area index (LAI), dry weight of leaf, leaf sheath and stalk, grain yield and biomass increased with the increasing of nitrogen application rate with the same rates of phosphorus (P) and potassium (K) applications. Contents of neutral detergent fiber(NDF) and acid detergent fiber(ADF) decreased with the increasing of nitrogen application rate, but increased with crop development. Content of crude protein performed increased with the increasing of nitrogen application rate, but decreased with the crop growth development. Content of NDF and ADF in the leaves were lower than those of leaf sheath under the same nitrogen rate. The quality of grains was also benefited from higher nitrogen application rates. Therefore, it can be concluded that optimum nitrogen fertilizer application can improve yield and quality of grain-forage maize and 300 kg·ha-1 of N was the optimum rate for maize growth in furrows of completely mulched alternating narrow and wide ridges systems, in semiarid areas in the Loess Plateau.
In order to explore the influence of soil improvers on the growth, turning green and yield of perennial ryegrass in rocky desertification land, the pot experiment was conducted with exogenous cattle manure carbon, wormcast, water retaining agent, longterm organic compound fertilizer, straw powder， and so on. With application of wormcast, seedling emergence time reduced by 50.00%, seedling emergence rate and tiller number(60 d) increased by 46.24% and 46.34%, respectively, compared with the treatments without using soil improvers. This treatment was better than the treatments with other soil improvers applications. The increase of plant height and fresh weight of perennial ryegrass were the highest with the application of compound fertilizer. The turning green recovery time, plant height, fresh weight and tiller number of the treatment with straw power were the best during the turning green recovery period. In conclusion, the improving effects of different improvers on ryegrass growth decreased in the following order: wormcast>compound fertilizer, cow dung carbon, water retaining agent>CK>straw power. The improving effects of different improvers on turning green recovery decreased in the following order: straw powder>compound fertilizer, wormcast, waterretaining agent>CK>cow dung carbon. These results suggested that the optimum soil improvers can promote the growth of perennial ryegrass.
Mealworm (Tenebrio molitor) and duckweed (Lemna minor) are living in high density and breeding quickly and both of them are important bioresource and may play a significant role in agriculture. In order to assess the value of duckweed applied to feed mealworm larva, parallel tests were carried out. The results showed that mealworm larvae feed fresh duckweed well, however if the additive proportion of fresh duckweed was over 80%, the growth of mealworm larvae was impeded although the contents of protein and crude fat in body had no significant difference. When the mass percentage of fresh duckweed and wheat bran was 65% and 35% , respectively, the feed cost of mealworm larvae reduced by 33.95% without effects on the breeding period, harvest yield and quality of mealworm larvae. The study showed that fresh duckweed was feasible to feed mealworm larvae.
Dry-Weight-Rank Method (DWR) is a method of estimating the substance and biomass of grassland through the corrected quadrat and establishing the calculation models. The method was originally widely used in pasture, rarely for grassland. However, in recent years, it had been gradually extending to grassland in Australia and Europe. To prove that if this method could apply to the investigation of grassland, we chose the alpine meadows of Luqu in the south of Gansu Province and the typical steppe of Siziwangqi in Inner Mongolia as the study area, which used to compare the dominant species and aboveground biomass using DWR and conventional method (CM). The results showed that the dominant species are Kobresia pygmaea, Carex atrofusca, Potentilla anserine by CM and Kobresia pygmaea, Poa pratensis, Potentilla anserine by DWR in alpine meadow, and Stipa krylovii. Agropyron cristatum, Cleistogenes squarrosa by CM and DWR in typical steppe. There were no significant difference in the total aboveground biomass in alpine meadow (73.18 g·m-2, DWR；82.84 g·m-2，CM) （P>0.05）and the same applies to typical steppe (89.67 g·m-2, DWR；88.10 g·m-2，CM)（P>0.05) between two methods. In a conclusion, DWR is suitable to a certain extent for evaluation of natural grassland in China.
In the face of the current difficulties of household contract management for pasture, the governance strategy of pasture integration is widely accepted. The ways of grassland integration included the household, joint, cooperative and shareholding ranches which supported by practical experience, policy and theoretical research. Combined the governance by law with the “Commons” theory, the present paper deeply analyzed various ways of integration, and thought that the household ranch and joint ranch had not surpassed the scope of household contract management which was not ideal for pasture integration, and the shareholding ranch only had narrow and limited application in pasture integration. Only the cooperative ranch autonomously established by herdsmen is suitable for the current legal framework of pasture management mode. However, the family and joint ranches are still indispensably transitive alternatives.