Interactions of Neotyphodium gansuense, Achnatherum inebrians, and plant-pathogenic fungi.

Interactions of Neotyphodium gansuense, Achnatherum inebrians, and nine fungal pathogens were studied by tests of inhibition of four fungal pathogens by Neotyphodium endophytes in vitro and by inoculation of nine fungal pathogens on detached leaves of endophyte-infected (E+) and endophyte-free (E-) plants. Compared with the controls, most isolates of N. gansuense significantly inhibited the growth in vitro of, in decreasing order of inhibition, Bipolaris sorokiniana, Curvularia lunata, Fusarium acuminatum, and Alternaria alternata.

Symptomology and etiology of a new disease, yellow stunt, and root rot of standing milkvetch caused by Embellisia sp. in Northern China.

An Embellisia sp. has been established as the cause of a new disease of the herbaceous perennial forage legume, 'standing milkvetch' (Astragalus adsurgens Pall.) in Northern China, which severely reduces plant density and degrades A.

Biological and physiological characteristics of Neotyphodium gansuense symbiotic with Achnatherum inebrians.

Biological and physiological characteristics of Neotyphodium gansuense were compared with Neotyphodium coenophialum and Epichloë festucae at a range of temperatures and pH values, and on carbon and nitrogen amended media. N. gansuense was able to grow at 10-30 degrees C, but not at 5 degrees C, and slowly at 35 degrees C.

[Soil seed banks of different grassland types of Alashan arid desert region, Inner Mongolia].

Investigations on the soil seed banks of different grassland types of Alashan arid desert region in Inner Mongolia showed that when the altitudes of sampling plots increased from 1,370 m to 1,750 m, the soil seed densities of natural grasslands decreased from 326 grain.m-2 to 76 grain.m-2.

[Root system development ability of several alfalfa cultivars in the hilly and valley regions of Loess Plateau].

A field study was conducted in the hilly and valley regions of Loess Plateau in Gansu Province to analyze the root system development ability of several alfalfa (Medicago sativa) cultivars. Eight introduced cultivars and one local cultivar were arranged in the same site. The secondary roots of alfalfa cultivars grew mainly from the taproot underground 10-20 cm depth, and there were no secondary roots below 50 cm depth.

[Development of APSIM (agricultural production systems simulator) and its application].

Soil-crop simulator model is an effective tool for providing decision on agricultural management. APSIM (Agricultural Production Systems Simulator) was developed to simulate the biophysical process in farming system, and particularly in the economic and ecological features of the systems under climatic risk. The current literatures revealed that APSIM could be applied in wide zone, including temperate continental, temperate maritime, sub-tropic and arid climate, and Mediterranean climates, with the soil type of clay, duplex soil, vertisol, silt sandy, silt loam and silt clay loam.

[Research progress and trend on grassland agroecology].

The connotation, progress, research frontiers and developmental trend of grassland agroecology are discussed in this paper. The interface theory, structure and function, coupling and discordance, and health assessment of grassland agroecosystems were recognized as the four research frontiers of the discipline. There exist three primary interfaces in a grassland agroecosystem, i.

[Dynamics of forage supplement and nutrition requirements of grazing sheep in alpine grasslands].

The dynamics of forage supply and nutrition requirements of sheep were monitored for a whole year under alpine grassland conditions in Sunan County, Gansu Province. The digestion and metabolism of grazed sheep were determined in different seasons. The results showed that the DE(9.

[Water distribution patterns in different degraded desert grasslands of Reaumuria soongorica].

Water distribution pattern and water use-efficiency in soil-plant-atmosphere system for light, medium, and heavy degraded Reaumuria soongorica grasslands were studied in Alashan region of Inner Mongolia. The total precipitation in 2001 was 124.3 mm, of which 119.

[Response of alfalfa seed to stress storage conditions].

The seed germination rate, seed mortality, seedling length, and infection rate of alfalfa (Medicago sativa L. cv. 'Longdong') were measured at constant temperature 20 degrees C every 60 days during one year storage period after inoculated or no inoculated by Fusarium avenaceum under room temperature (RT), 35 degrees C, and 35 degrees C and +10% seed moisture content (SMC) conditions.

[Response of seed germination of three xeromorphic shrubs to drought stress].

The seed germination, seedling growth and water absorption characteristic of Caragana korshinskii, Hedysarum scoparium, and Artemisia sphearocephala were investigated under different osmotic potentials (PEG 6000, -0.3(-) -2.7 MPa).

[Variation in seed yield components among varieties of Poa pratensis].

Seed yield and its characteristics of 28 varieties of Poa pratensis in field plots at Lanzhou, China were evaluated in 2001. The results showed that the seed yields among the varieties were significantly different (P < 0.01) by LSD test.

[Effect of pesticides on field-controlling root rot of Vicia faba].

The effect of pesticides on field-controlling root rot of Vicia faba was studied in two consecutive years by seed treatment of fungicides and their combination. The results of the first year field experiments showed that among the 11 treatments tested, triadimefon of 0.01 g a.

[Effect of soil compaction on Vicia faba of growth in the Loess Plateau].

The effect of soil compaction on the growth of Vicia faba was studied by pot experiment, field plot experiment, and farmers' field production during two consecutive years. The results showed that increasing soil bulk density at 0-7 cm depth significantly decreased the root and shoot dry weight per plant, increased plant mortality caused by Fusarium species, and decreased seed yields. Field experiments indicated that compared to the plants grown on the plots with soil bulk density of 1.

[Eco-restoration of abandoned farmland in the Loess Plateau].

The vegetation on abandoned farmland was succeeded from Agriophyllum arenarium community to Lespedeza davurica community under cutting conditions. More plant species was recruited at the initial stage of restoration. The new plant species established earlier were annual Agriophyllum arenarium and perennial Pennisetum flaccidum which could be the dominant species or sub-dominant species.

[Characteristics of vegetation, soil, and their coupling of degraded grasslands].

This paper presented the characteristics of the vegetation, soil, and their coupling in the gradient of grazing pressure of the degraded alpine grassland in Sunan county and of the typical arid grassland in Huanxian county, Gansu province. The abundance index of species, Simpson index, Shannon-Wiener index, Cody index, nutrient functional diversity index and life type diversity index increased, while the Bray-Curtis index and nitrogen fixation diversity index decreased with the reduced grazing intensity in both types of degraded grassland. With reduced grazing pressure, the contents of total nitrogen, available nitrogen and organic matter in both grasslands and the content of available phosphorus in arid grassland at 0-40 cm soil depth were increased, and that of total phosphorus in alpine grassland was decreased, while phosphorus concentration in arid grassland showed no regular pattern of change.