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排序方式: 共有105条查询结果,搜索用时 15 毫秒
41.
Summary A survey of sarcosporidiosis made in healthy cattle slaughtered at Omdurman Central Abattoir gave an infestation rate of 98 per cent. Transmission of sarcocysts from cattle to mice was accomplished thus confirming the absence of host specificity.  相似文献   
42.
This study aimed to evaluate the effectiveness of hormonal treatments on ovarian activity and reproductive performance in Barki and Rahmani ewes during non‐breeding season. Forty‐eight multiparous ewes, 24 Barki and 24 Rahmani ewes were divided into two groups, 12 lactating and 12 dry ewes for each breed. Controlled internal drug release (CIDR) device was inserted in all ewes for 14 days in conjunction with intramuscular 500 IU equine chronic gonadotrophin (eCG) at day of CIDR removal. Data were analysed using PROC MIXED of SAS for repeated measures. Breed, physiological status and days were used as fixed effects and individual ewes as random effects. Barki ewes recorded higher (p < .05) total number of follicles, number of large follicles, serum estradiol concentration and estradiol: progesterone (E2:P4) ratio compared to Rahmani ewes. Lactating ewes recorded higher (p < .05) number of small follicles and lower concentration of total antioxidant capacity (TAC) compared to dry ewes. Number and diameter of large follicles recorded the highest (p < .05) values accompanied with disappearance of corpora lutea at day of mating. Serum progesterone concentration recorded lower (p < .05) value at day of mating and the highest (< .05) value at day 35 after mating. CIDR‐eCG protocol induced 100% oestrous behaviour in both breeds, but Rahmani ewes recorded longer (< .05) oestrous duration compared to Barki. Conception failure was higher (< .05) in Barki compared to Rahmani ewes. In conclusion, CIDR‐eCG protocol was more potent in improving ovarian activity in Barki compared to Rahmani ewes, but this protocol seems to induce hormonal imbalance in Barki ewes that resulted in increasing conception failure compared to Rahmani ewes.  相似文献   
43.
We report the impact of human-induced desertification on the species richness, abundance, and composition of sand dune flora and herpetofauna of North Sinai, Egypt. Our hypothesis was that degraded habitats would have reduced vegetation complexity, richness, and abundance, and consequently lower reptile species richness and abundance. We also hypothesized that desert lizards would not follow the typical generalist/specialist responses to habitat degradation found in other biomes. Instead, we predicted that because vegetation loss intensifies the environmental extremity of deserts, those species specialized for open and sandy environments would be more likely to persist in desertified habitats than would desert generalists. Our results showed that areas protected from vegetation loss did not have significantly higher vegetation richness or abundance except for only a few species. However, protected sites did have significantly higher percent vegetation cover and height. Habitat protection clearly had strong effects on the reptile community as species richness and abundances were significantly higher in protected sites. The composition of the reptile community between protected and unprotected sites differed significantly. Contrary to past studies in other environments, desert generalist species were not able to persist in degraded sites and were only found in protected sites. Specialist species were ubiquitous in that they occurred in both areas protected and unprotected from vegetation loss. We propose that the effects of disturbance on species composition (specialists or generalists) depends on whether the disturbance exacerbates or reduces environmental harshness and the conditions that favor specialization. In extreme environments, specialist and generalist responses to habitat degradation are opposite to that of more productive environments.  相似文献   
44.
ABSTRACT

Sulfur (S) availability is a characteristic of conservation tillage. We studied the effects of S on sunflower yield and fatty acid profile under conventional and conservation tillage in silty clay soil of D.I. Khan, Pakistan. Conventional tillage consisted of disk plowing followed by tiller and rotavator, while conservation tillage comprises tiller and disc harrowing. Treatments comprise six sulfur levels (S1 = 0, S2 = 20 kg S ha?1 at sowing, S3 = 10 kg S ha?1 at sowing +10 kg S ha?1 25 days after sowing (DAS), S4 = 40 kg S ha?1 at sowing, S5 = 20 kg S ha?1 at sowing + 20 kg S ha?1 25 DAS, and S6 = 20 kg S ha?1 at sowing + 10 kg S ha?1 25 DAS + 10 kg S ha?1 50 DAS) replicated thrice. After 2 years of experimentation, soil samples were collected (from 0 to 0.30 m depth) for organic matter (OM), total soil N (TSN), and available sulfur analysis. Conservation tillage significantly increased OM, TSN, and S contents in 0–0.30 m soil compared to conventional tillage. Likewise, sunflower plants showed higher achene yield, better fatty acid profile, and net economic returns in conservation tillage than in conventional tillage. Application of 20 kg S ha?1 at sowing and 10 kg S ha?1 at each 25 and 50 DAS recorded significantly higher achene yield, higher oil, and linoleic acid contents; however, oleic and oleic/linoleic ratio did not increase with higher S rates. Conservation tillage was effective in increasing OM, TSN, and available S besides increasing yield and economics in silty clay soil.  相似文献   
45.
稻瘟病菌孢子对水稻叶表附着量的研究   总被引:4,自引:1,他引:4  
针对叶稻瘟病侵染中的一个环节,通过疫区及室内模拟的多年试验,分别找出该病菌分生孢子稻田低空浮游量与田间前一天病情指数、20:00时温度、相对湿度、日照时数及当天最低温度的数学关系式;得出该浮游量与水稻叶表附着量的转换值;寻出不同生长阶段稻株单位叶面积病菌分生孢子的附着系数及各叶位叶片的附着率;并结合田间水稻叶面积情况组装该侵染环节的数学模型。  相似文献   
46.
杂交稻制种母本撒直播的花遇规律及成因研究   总被引:3,自引:1,他引:3  
近年发现,杂交稻春、夏季制种母本撒直播比移栽的异交结实率高5%左右。经试验观察,父、母本日开花相遇机率提高3.5%,时开花相遇机率提高6.5%。前者由两亲本成穗结构相似所致,后者与母本撒直播的群体密度大、有效穗多、调节田间小气候使母本开花提早有关。  相似文献   
47.
48.
粳系21—2一般亩产400公斤左右,在安徽省区试和生产试验中,平均比鄂宜105增产5.8%。全生育期125—130天,株高80~90厘米,株、叶形适中,分蘖力中等,生长清秀,熟色好。平均每穗70余粒,结实率85—90%,千粒重约25克,米质优良。对主要病害有一定的田间抗性。适宜在中等肥力条件下栽培。其适宜播期为6月18—25日,秧田播种量40—50公斤,秧龄30—35天。大田亩栽2.5—3.0万穴,基本苗15—20万。在肥力中等田块,亩需纯氮9公斤左右,适当搭配磷钾肥。以基肥为主,早施追肥,后期控制用氮。够苗及时烤田,后期不断水过早,并加强病虫预防。  相似文献   
49.
Abstract

This study was conducted in the farmer field between the years 2014 and 2015. In this study, 3 doses of potassium (K) (0, 10, and 20?kg da?1) of K2SO4 (50% K2O) fertilizer and 3 doses of humic acid (HA) (0, 20, and 40?kg da?1) (85% HA) were used. Increase in the HA dose reflected significant effects on pH, salt, organic matter, phosphorus, magnesium, iron, and manganese contents of the experiment area at p?p?p?p?p?相似文献   
50.
Non-destructive and real-time oil palm fresh fruit bunch (FFB) grading systems are of major exploratory concern for researchers in the oil palm industry. The objective is to reduce time, labour, costs, and most importantly, to increase the oil extraction rate, in order to achieve a good quality of palm oil at a more acceptable price. This research investigates the potential of flavonoids and anthocyanins as a predictor to classify the degree of oil palm FFB ripeness. This paper also discusses the relationship between these predictors and the ripeness categories period. One hundred and eighty oil palm FFB samples were collected from a private plantation in Malaysia, according to three maturity categories i.e., ripe, under-ripe, and over-ripe. Each sample was randomly scanned 10 times, both front and back using a hand-held Multiplex®3 multi-parameter fluorescence sensor. The results show that flavonoid and anthocyanin content decreased from immature to over mature oil palm FFBs. Overall, the relationship using Pearson's correlation between flavonoids and anthocyanins was r2 = 0.84 and the most outstanding relationship accuracy was at the over-ripe stage, at 90%. Statistical analysis using analysis of variance (ANOVA) and pair-wise testing proved that both predictors gave significance difference between under-ripe, ripe, and over-ripe maturity categories. This shows that both predictors can be good indicators to classify oil palm FFB. Classification analysis was performed by using both predictors together and separately through several methods. The highest overall classification accuracy was 87.7% using a Stochastic Gradient Boosting Trees model and with both predictors. The other classification methods used either independent or both predictors together and gave various results ranging from 50 to 85% accuracy. This research proves that flavonoids and anthocyanins can be used as predictors of oil palm maturity classification.  相似文献   
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