Chemical Composition and Ruminal Digestibility of Ceratoides, a Salt-tolerant Perennial Plant,at Different Years

It has been proposed that salt-tolerant plant could be used as a feed resource for ruminants whereby salt would be removed from salinized land (Asian -Aust. J. Anim. Sci. (2002) 15:998 -1001). Ceratoides arborescens (Losinsk.) Tsien et C. G. Ma is known as a drought-and salt-tolerant plant,a kind of shrubs, growing in semi-arid land of Inner Mongolia. Because the covering effect of the perennial plant as a mulch over the soil might be expected, the optimum covering effect would be obtained after the growth period.The perennial plant produces seeds around summer and end its growth thereafter. Nutrient value of the perennial salt-tolerant plant, however,had not been reported in flowering period at different year. It is necessary to know the ruminal degradability of the plants of each growing year in order to determine the regimen to diet for ruminants. The present experiment,therefore,was undertaken to analyze the digestibility and chemical composition of Ceratoides arborescens as feed for ruminants.

Environmental Indicators Related to Native Plants to Assess the Quality of Life in the Degraded Desert Area

In Kuwait, the scarcity and irregularity of rainfall, the availability of areas of sand supply and the prevalence of strong north westerly winds significantly influence the stability of the fragile ecosystem. Naturally, grown native shrubs and trees can provide potential shelter to soil surface in desert areas. To study the environmental indicators provided by native plant and their ability to improve quality of life, the morphological properties of the vegetated nabkhas within different areas in Kuwait desert and within protected area were assessed. The vegetated dunes can trap maximum mobile sediments from 10.5 to 0.45 ton thus cost saving per plant estimated to be from 5.5 to 0.24 USD. The arrangements of the native plant from highest efficiency in absorbing carbon dioxides to the least were as follows: Nitraria retusa, Haloxylon salicornicum, Citrullus colocynthis, Tamarix aucheriana, Lycium shawii, Convolvolus oxyphyllus, Rhanterium epapposum, Panicum turgidum, Calligonum polygonoides, Astragalus spinosus, Cyperus conglomerates. The cost saving of CO_(2) per year estimated to be from 0.95 to 1,542.1 USD. The revegetation enhanced physical and chemical quality of soil and created microenvironments for the flora and fauna. The aim of this paper is to identify the environmental indicators related to native plants for the assessment of quality of life.

Dynamics of arbuscular mycorrhizal fungi associated with desert ephemeral plants in Gurbantunggut Desert

Previous studies documented that most desert plants can be colonized by arbuscular mycorrhizal （AM） fungi, however, little is known about how the dynamics of AM fungi are related to ephemerals in desert ecosystems. The dynamics of AM fungi with desert ephemerals were examined to determine the effects of host plant life stages on the development of AM fungi. Mean colonization of ephemeral annual plants was 45% lower than that of ephemeral perennial plants. The colonizations were much higher in the early part of the growing season than in later parts, peaking at flowering times. The phenology of AM fungi in root systems varied among different ephem- erals. The density of AM fungal spores increased with the development of ephemeral annual plants, reached its maximum at flowering times, and then plateaued about 20 days after the aboveground senescence. A significant positive correlation was found between AM fungi spore density and biomass of ephemeral annual plants. The life cycles of AM fungi associated with desert ephemerals were very shod, being about 60-70 days. Soil temperature and water content had no direct influence on the development of AM fungal spores. We concluded that the development of AM fungi was in response to desert ephemeral phenology and life history strategy.

The central role of stem cells in determining plant longevity variation

Vascular plants display a huge variety of longevity patterns,from a few weeks for several annual species up to thousands of years for some perennial species.Understanding how longevity variation is structured has long been considered a fundamental aspect of the life sciences in view of evolution,species distribution,and adaptation to diverse environments.Unlike animals,whose organs are typically formed during embryogenesis,vascular plants manage to extend their life by continuously producing new tissues and organs in apical and lateral directions via proliferation of stem cells located within specialized tissues called meristems.Stem cells are the main source of plant longevity.Variation in plant longevity is highly dependent on the activity and fate identity of stem cells.Multiple developmental factors determine how stem cells contribute to variation in plant longevity.In this review,we provide an overview of the genetic mechanisms,hormonal signaling,and environmental factors involved in controlling plant longevity through long-term maintenance of stem cell fate identity.

以色列严重退化旱地长期恢复对土壤和植被的影响

Land degradation affects extensive drylands around the world.Due to long-term misuse,the Israeli Sde Zin dryland site has faced severe degradation.The study objective was to assess the feasibility of passive restoration in recovering the site.The study was conducted in four land-units along a preservation-degradation continuum:(1)an area that has not faced anthropogenic disturbances(Ecological land);(2)an area that was proclaimed as a national park in the 1970s(Rehabilitation);(3)an area that was prone,until recently,to moderate anthropogenic pressures(Triangle);and(4)a dirt road that was subjected to long-term off-road traffic(Dirtroad).Soil was sampled and analyzed for its properties.The soil physical quality followed the trend of Ecological land>Rehabilitation>Triangle>Dirtroad.Specifically,high soil salinity in the latter three land-units is attributed to long-term erosional processes that exposed the underlying salic horizons.Herbaceous and shrubby vegetation cover was also monitored.The herbaceous vegetation cover followed the trend of Ecological land(86.4%)>Rehabilitation(40.3%)>Triangle(26.2%)>Dirtroad(2.1%),while the shrubby cover was 2.8%in the Ecological land-unit,and practically zero in the other land-units.It seems that despite the effectiveness of passive restoration in recovering the soil’s physical properties,the recovery of vegetation is limited by the severe soil salinity.