The Effects of Vegetation Type on Oedaleus decorus asiaticus (Orthoptera: Acrididae) Oviposition and Hatching Success

Oedaleus decorus asiaticus (Bei-Bienko, 1941) has been regarded as one of the most dominant locusts in the northern grassland, the adjacent area of agriculture and animal farmland, in China. The aims of this study were to investigate the effects of vegetation type on the oviposition behavior of this pest in an open field and the hatching success of the offspring in the following year. The results showed that vegetation type did have a significant effect on whether any egg pods were laid by O. d. asiaticus. Once the females laid eggs, vegetation type and cage number had a significant effect on the number of egg pods laid. The highest number of egg pods was found in the Cleistogenes squarrosa treatment, followed by Stipa krylovii and then Leymus chinensis, while the Artemisia frigida treatment contained the lowest number of egg pods. The O. d. asiaticus eggs laid in S. krylovii and C. squarrosa treatments had a significantly higher hatching success rate (over 53%) than the other two grasses (below 40%). In short, habitats with C. squarrosa and S. krylovii grasses are likely to be preferred by ovipositing females, thus population monitoring efforts of O. d. asiaticus should focus on these habitats.

The Capacity of grass species shoots to recovery of steppe and desert steppe zones

In this research study we determined regeneration capacity of the dominate vegetative plants and shoot formation in steppe and desert-steppe zones. To determine shoot regeneration we selected Stipa krylovii from the steppe zone and Stipa gobica, Cleistogenes songorica from desert steppe zones. In the results from research study Stipa krylovii and Cleistogenes songorica did not differ in number of bushes regardless of the degree of degradation of the plants; Stipa gobica had 3 times more bushes than others in the slightly degraded pastures. In slightly degraded pasture Stipa krylovii had a relatively young, with a normal bush however in moderately degraded pasture with fall apart and died bush. Хээр, цөлийн хээрийн бэлчээрийн биелэгтэн ургамлын найлзуурын нөхөн сэргэх чадавхи Хээр, цөлийн хээрийн бэлчээрийн ургамлын нөхөн сэргэх чадавхийг тодорхойлох зорилгоор ХААИС-ийн Экосистемийн судалгааны төвийн хээр, цөлийн хээрийн бүсийн бэлчээрийн цэнэлийн судалгааны талбайд судалгааг гүйцэтгэсэн. Найлзуурын нөхөн сэргэлтийг тодорхойлохоор хээрийн бүсээс Stipa krylovii, цөлийн хээрийн бүсээс Stipa gobica, Cleistogenes songorica гэсэн 3 зүйл биелэгтэн ургамлуудыг сонгон авсан. Судалгаагаар биелэгтэн ургамлуудаас Stipa krylovii, Cleistogenes songorica гэсэн 2 зүйл ургамал доройтлын зэргээс үл хамааран бутны тооны хувьд огт ялгаагүй, харин Stipa gobica бага доройтсон бэлчээрт бусдаасаа 3 дахин их буттай, бага зэрэг доройтсон бэлчээрт Stipa krylovii харьцангуй залуу бөгөөд хэвийн буттай, дунд зэрэг доройтсон бэлчээрт харьцангуй задарч мөхсөн бутнууд буйг тус тус тогтоож, зонхилогч биелэгтэн ургамлын бутны тоо, диаметрийн үзүүлэлтээр нөхөн сэргэх чадавхийг илрүүлж, харин биелэгтэн ургамлын найлзуурын өндрөөр нөхөн сэргэх чадавхи илэрхийлэгдэхгүй болохыг илрүүлэлээ. Түлхүүр үг: бэлчээрийн доройтол, цэнэл, найлзуур, бут

Application of Plant Growth Regulators to Stipa krylovii in the Xilin Gol Grassland

ABSTRACT: Plant growth regulators are an immense group of substances that have the ability to alter growth pattern of plants and can be used for improving plant growth and productivity. A study was conducted in the Xilin Gol grassland of Inner Mongolia, China, to ascertain the growth and biomass production of Stipa krylovii in response to exogenous application of different growth regulators at various concentrations viz. naphthalene acetic acid (NAA), 6-benzylaminopurine (6-BA), brassinosteroid (BR), sodium nitrophenolate (SNP) and forchlorfenuron, and gibberellic acid (GA3). Application of growth regulators significantly enhanced the growth and biomass production of S. krylovii. The height of vegetative shoot was enhanced mostly by the application of 100 mg L-1 GA3, while, height of reproductive shoot was increased by 25 mg L-1 6-BA, 100 mg L-1 SNP + 5 mg L-1 forchlorfenuron and 50 mg L-1 SNP + 2.5 mg L-1 forchlorfenuron as compared to control. Fresh biomass was enhanced by the application of 0.02 mg L-1 BR, 10 mg L-1 SNP + 0.5 mg L-1 forchlorfenuron and 50 mg L-1 SNP + 2.5 mg L-1 forchlorfenuron. Application of 5 mg L-1 6-BA and 50 mg L-1 SNP + 2.5 mg L-1 forchlorfenuron proved to be more beneficial in improving dry biomass of S. krylovii, as compared to control. In conclusion, exogenous application of different growth regulators improved growth and biomass production of S. krylovii. Furthermore, application of SNP + forchlorfenuron and 6-BA was more effective.

CHANGES OF CONTENT OF FREE AMINO ACIDS IN GRAINS OF FOREST GROWING EASTERS OF EASTER TRANSBAIKALIA IN PULLING IN OSMOSITIC STRESS

In the course of studying the content of free amino acids in dry and germinating grains of wild cereals, some biochemical features of their dynamics were revealed depending on the osmotic pressure. In most species, except Agropyron cristatum, a significant increase in the concentration of amino acids occurred in the control on the first day after the start of the experiment; in the subsequent period, their decrease was observed. For Agropyron cristatum, a decrease in the index and a smooth increase after the first day were observed. Under the influence of osmolyte, the tendency to mobilize amino acids has changed and in some species (Stipa krylovii, Melica virgata, Melica turczaninowiana) the maximum amounts were observed on the first day from the beginning of the experiment, in the others to the second day. The total amount of free amino acids in the control and in the test was not significantly different. There was also a rapid mobilization of proteinogenic amino acids with increasing osmotic stress for the widespread Stipa krylovii and Agropyron cristatum in the region. A similar trend was noted for the xerophyte Tripogon chinensis. For grasses with a narrow ecological niche, which are characterized by xeromesophilia, osmotic stress suppressed the rapid mobilization of free amino acids. The content of individual groups of amino acids under the influence of osmotic stress was characterized by significant differences for species of the Melica genus in the number of acidic amino acids, for Tripogon chinensis an increase in the content of basic amino acids, and for Agropyron cristatum by a decrease in their concentration.

Biological and ecological evidences suggest Stipa krylovii (Pooideae), contributes to optimal growth performance and population distribution of the grasshopper Oedaleus asiaticus

Oedaleus asiaticus Bey. Bienko is a significant grasshopper pest species occurring in north Asian grasslands. Outbreaks often result in significant loss in grasses and economic losses. Interestingly, we found this grasshopper was mainly restricted to Stipa-dominated grassland. We suspected this may be related to the dominant grasses species, Stipa krylovii Roshev, and hypothesized that S. krylovii contributes to optimal growth performance and population distribution of O. asiaticus. A 4 year investigation showed that O. asiaticus density was positively correlated to the above-ground biomass of S. krylovii and O. asiaticus growth performance variables (survival rate, size, growth rate) were significantly higher in Stipa-dominated grassland. A feeding trial also showed that O. asiaticus had a higher growth performance when feeding exclusively on S. krylovii. In addition, the choice, consumption and the efficiency of conversion of ingested food (ECI) by O. asiaticus was highest for S. krylovii compared with other plant species found in the Asian grasslands. These ecological and biological traits revealed why O. asiaticus is strongly associated with Stipa-dominated grasslands. We concluded that the existence of S. krylovii benefited the growth performance and explained the distribution of O. asiaticus. These results are useful for improved pest management strategies and developing guidelines for the monitoring of grasshopper population dynamics against the background of vegetation succession and changing plant communities in response to activities such as grazing, fire and climate change.