Effects of soil nitrogen:phosphorus ratio on growth rate of Artemisia ordosica seedlings

To address how the ratios of nitrogen and phosphorus (N:P ratios) in soil affect plant growth, we performed a two-factor (soil available N:P ratios and plant density) randomized block pot experiment to examine the relationships between soil N:P ratios, and the N:P ratios and growth rate of Artemisia ordosica seedlings. Under moderate water stress and adequate nutrient status, both soil N:P and plant density influenced the N:P ratios and growth rates of A. ordosica. With the increase of soil N:P ratios, the growth rates of A. ordosica seedlings decreased significantly. With the increase of soil N:P ratios, N:P ratios in A. ordosica seedlings increased significantly. While the nitrogen concentrations in the plant increased slightly, the phosphorus concentrations significantly decreased. With the increase of plant density, the shoot N:P ratios and growth rates significantly decreased, which resulted from soil N:P ratios. Thus, soil N:P ratios influenced the N:P ratios in A. ordosica seedlings, and hence, influenced its growth. Our results suggest that, under adequate nutrient environment, soil N:P ratios can be a limiting factor for plant growth.

Effects of soil nitrate:ammonium ratio on plant carbon:nitrogen ratio and growth rate of Artemisia sphaerocephala seedlings

Can soil nitrate： ammonium ratios influence plant carbon： nitrogen ratios of the early succession plant？ Can plant carbon： nitrogen ratios limit the plant growth in early succession？ To address these two questions, we performed a two-factor （soil nitrate： ammonium ratio and plant density） randomized block design and a uniform-precision rotatable central composite design pot experiments to examine the relationships between soil nitrate： ammonium ratios, the carbon： nitrogen ratios and growth rate of Artemisia sphaerocephala seedlings. Under adequate nutrient status, both soil nitrate： ammonium ratios and plant density influenced the carbon： nitrogen ratios and growth rate of A. sphaerocephala seedlings. Under the lower soil nitrate： ammonium ratios, with the increase of soil nitrate： ammonium ratios, the growth rates of plant height and shoot biomass of A. sphaerocephala seedlings decreased significantly; with the increase of plant carbon： nitrogen ratios, the growth rates of shoot biomass of A. sphaerocephala seedlings decreased significantly. Soil nitrate： ammonium ratios affected the carbon： nitrogen ratios of A. sphaerocephala seedlings by plant nitrogen but not by plant carbon. Thus, soil nitrate： ammonium ratios influenced the carbon： nitrogen ratios of A. sphaerocephala seedlings, and hence influenced its growth rates. Our results suggest that under adequate nutrient environment, soil nitrate： ammonium ratios can be a limiting factor for the growth of the early succession plant.

Effect of plant growth regulator on rate of twin seedlings of rice with polyembryony

Rice with polyembryony characterized bytwin seedlings is a good genetic tool for apomixisresearch.A study on the effect of five plantgrowth regulators(IAA,KT,GA,2,4-D and6-BAP)on rate of twin seedlings in 3 rice varie.ties with polyembryony(Shuang 3,Shuang 13and Lu 52)was conducted.The results showed

Application of Rare Earth Phosphate Fertilizer in Western Area of China

Rare earth phosphate fertilizer (REPF) as base fertilizer (750 kg per hm2) was applied in the western area of China during the 'Tenth Five-Year Plan' , and the results show as follows: compared with calcium superphosphate (CK), REPF increases crops yields for maize by 17.0% , for rice by 10.5% , for wheat by 24.2% , for potato by 18.5% , for cabbage by 16.3%, for Chinese cabbage by 16.4%, for beet by 6.5%; decreases the diseased plant rate for common smut of maize by 1.0%, for maize stalk rot by 1.2%, for wheat take-all disease by 7.8%, for wheat root rot by 3.2%, for potato blackleg disease by 1.4%, for potato late blight by 6.6%; increases the sugar content of beet by 0.9°S.

Resistance in Barley (<i>Hordeum vulgare</i>L.) to New Invasive Aphid, Hedgehog Grain Aphid (<i>Sipha maydis</i>, Passerini) (Hemiptera: Aphididae)

Sipha maydis Passerini (Hemiptera: Aphididae) is a pest of cereals in many regions of the world and was identified as an invasive pest of the US in 2007. Regional surveys from 2015-2017 revealed this pest was broadly distributed throughout many of the western Great Plains states where it is a potential threat to cereal production. The common name hedgehog grain aphid, HGA, has been associated with Sipha maydis in the US. Cross-resistance where a plant is resistant to one aphid species and is also resistant to another species that is known to occur. Six barleys were evaluated for cross-resistance to HGA: Russian wheat aphid, RWA, resistant germplasms STARS 9301B and STARS 9577B and cultivar “Mesa”;greenbug, GB, resistant germplasm STARS 1501B and cultivar “Post 90”;and RWA and GB resistant experimental line 00BX 11-115. Cultivars “Morex” and “Schuyler” were susceptible controls. Antixenosis was measured 5 days after infestation by HGA. Seedling damage ratings and reductions in seedling growth were recorded after 17 days of infestation. Intrinsic rate of increase, rm, of HGA was determined by following the development of newborn aphids to adulthood and reproduction. 00BX 11-115 and Post 90 had significantly greater antixenosis (fewer aphids/seedling), significantly lower plant damage ratings, and significantly lower intrinsic rates of increase than other entries. Differences in seedling growth were not significant. 00BX 11-115 and Post 90 were the only entries with the Rsg1 greenbug resistance gene. Rsg1 greenbug resistance confers cross-resistance to HGA in the seedling stage.