Mercury antagonists: protection of plants against vapor injury by thiamine and other compounds

Mercury vapor-induced abscission ofColeus cuttings was prevented by Thiamine, other organo-S (Se) compounds and selenite, but not by common sugar metabolites, amino acids, non-auxin growth regulators and selenate. Protection was also afforded to other plants including ferns and gymnosperms. Thus the compounds that protect plants against Hg intoxication correspond to the Hg antagonists known in animals including man.     

Is the Production of Embryos in Small‐Scale Farming an Economically Feasible Enterprise?

The present assay attempts to evaluate the feasibility of using embryo transfer in small community farmers by in vivo study and by modelling the results obtained. From the total of 59 donor cows, 62.7% responded to treatment, with a significant difference (p = 0.002) in the percentage of the response between breeds, being 90.5% (19/21) in Holstein and 47.4% (18/38) in Brahman. A total of 283 embryos were graded as transferable, while 141 as non‐transferable, without difference in the percentage of transferable embryo by breed (p = 0.18). The mean of transferable embryos graded as class I and II was not different between Holstein and Brahman (p = 0.96 and p = 0.92, respectively); besides, no differences were observed in the other grades (non‐transferable). The highest difference in costs, regardless of its quality by breed, was seen in the lower levels of probable fertility of the embryo transferred, even reaching several hundred dollars. When modelling the expected costs for embryo produced and transferred, values can reach nearly $2000.00 when the probable fertility is only 10%. However, when the probable fertility was 60%, embryo cost was close to $300.00. This technology seems to be viable on average or high‐scale systems, having a superovulatory response between 60 and 80% with 4–6 transferrable embryos. Yet, in small‐scale farming, due to the reduced number of donors and/or recipients, the costs surpass the economical feasibility of the technique.     

Effect of gradual acclimation to high ambient temperatures on egg‐shell quality of the Sinai Bedouin fowl,the commercial white leghorn and their crossbreds

1. The effect of gradual acclimation to high ambient temperatures on egg‐shell quality was studied in the Sinai fowl, the commercial White Leghorn, and their reciprocal crossbreds.

2. The Leghorn egg was characterised by a thinner and weaker shell compared with the Sinai and the crossbreds, at all the experimental temperatures.

3. In contrast to other reports, high ambient temperatures for a long period had only mild effects on egg‐shell quality.

4. The results suggest that gradual acclimation to high ambient temperatures might improve the efficiency of the physiological mechanisms involved in the hen's response to heat. Consequently, the reproductive process adapts to the hot environmental conditions.

5. The results indicate that the Sinai breed might be used for future selection of a breed, highly resistant to extreme environmental conditions and with an improved shell quality.     

加工番茄果秧分离参数优化及验证

为满足自走式番茄收获机国产化研究不断推进的需要,采用CCD(central composite design)设计与响应曲面分析(response surface methodology,RSM)对果秧分离性能作优化研究。以收获生产率、摇摆器转速、输料链速度为自变量,果秧分离性能(果秧分离率和果实破损率)为响应指标,建立了二者间的多元数学回归模型,探究了因素间的影响规律及最佳水平组合。通过Design Expert 9.0软件对试验参数进行优化,确定了在满足果秧分离率、果实破损率符合番茄收获机作业质量标准(NYT1824-2009)条件下的最优分离参数组合。结果表明:果秧分离率影响因素显著程度顺序为:摇摆器转速收获生产率输料链速;果实破损率影响因素显著程度顺序为:摇摆器转速输料链速收获生产率;最优参数组合为收获生产率34.2t/h、摇摆器转速为409.3r/min、输料链速为0.71m/s;对应的果秧分离率、果实破损率预测值分别为96.27%、2.12%。经验证,应用响应曲面分析法所得到的果秧分离参数是可行的,该研究可为加工番茄果秧振动分离技术的进一步研究提供理论基础和科学依据,亦可为果品振动收获技术参数的优化提供参考。     

Rapid survey for presence of a blast resistance gene Pi-ta in rice cultivars using the dominant DNA markers derived from portions of the Pi-ta gene

The Pi‐ta gene in rice confers resistance to strains of the blast pathogen Magnaporthe grisea (Herbert) Borr. (anamorph Pyricularia oryza Cav.) containing the corresponding avirulence gene AVR‐Pita in a gene‐for‐gene fashion. The Pi‐ta gene is a typical nucleotide‐binding site type resistance gene. Nucleotide sequences distinguishing the resistant Pi‐ta and susceptible pi‐ta alleles were previously identified and used for developing DNA markers for a resistant Pi‐ta haplotype and three susceptible pi‐ta haplotypes. In the present study, the existence of the Pi‐ta gene in 141 rice germplasm accessions was rapidly determined using these markers, and the results were confirmed by inoculating rice germplasm with an M. grisea strain containing AVR‐Pita. The Pi‐ta gene was found in accessions from several major rice producing countries, including China, Colombia, Japan, Vietnam, the Philippines, Iran and the United States. The usefulness of DNA markers for rapid determination of the genotype of rice germplasm was thus demonstrated. The Pi‐ta gene also was found in rice cultivar known to contain the Pi‐ta² gene, although the allelic relationship of these genes remains to be determined. The presence of the Pi‐ta gene in landrace cultivars in several different geographical locations, the Philippines and Vietnam, other indica rice cultivars in China and Colombia suggest that the Pi‐ta gene may have spontaneously originated in indica rice cultivars. These results are useful for incorporating the Pi‐ta gene into advanced breeding lines by marker‐assisted selection for rice breeding programmes worldwide.     

基于斜率比法评定断奶仔猪对不同铜源的相对生物学利用率

本试验旨在研究不同铜源（硫酸铜、碱式氯化铜和柠檬酸铜）和铜添加水平（20和30 mg/kg）对断奶仔猪生长性能、血清铜含量与含铜酶活性以及组织铜含量的影响,探讨断奶仔猪对不同铜源的相对生物学利用率。试验采用3×2双因子随机区组设计,选取平均体重为（8.98±0.48） kg的杜×长×大三元杂交断奶仔猪112头,随机分为7组,每组4个重复,每个重复4头猪。对照组饲喂玉米-豆粕型基础饲粮（铜含量为7.80 mg/kg）,各试验组分别在基础饲粮中添加20或30 mg/kg硫酸铜、碱式氯化铜或柠檬酸铜（均以铜含量计）。试验预试期3 d,正试期28 d。结果表明：1）试验组与对照组断奶仔猪平均日增重、平均日采食量和料重比均无显著差异（P>0.05）。2）饲粮铜源和铜添加水平对断奶仔猪血清铜含量具有显著影响（P<0.05）,但对血清铜蓝蛋白和铜锌超氧化物歧化酶活性均无显著影响（P>0.05）。3）饲粮铜源和铜添加水平对断奶仔猪肝脏铜含量具有显著影响（P<0.05）,但对心脏、肾脏、胰脏和跖骨铜含量均无显著影响（P>0.05）。4）根据多元线性回归斜率比法计算,以血清铜...     

Patterns of change in body condition in wintering Neotropical-Nearctic migratory birds in shaded plantations in the Andes

Despite the widely accepted idea that shaded plantations are valuable habitats for Neotropical migrants in disturbed landscapes, little empirical evidence is available in relation to the quality of this habitat for Neotropical-Nearctic migratory birds in the Andes. We evaluated the suitability of shaded plantations for overwintering Neotropical-Nearctic migratory birds by examining diurnal and seasonal variation in body condition of migrants in these agroforests in the Andes. During October to April 2008–2009 and 2009–2010, we mist-netted eight species of Neotropical-Nearctic migrants in shaded plantations in the Colombian Andes. Body condition improved throughout the day for Cerulean Warbler (Setophaga cerulea), Blackburnian Warbler (Setophaga fusca), Tennessee Warbler (Leiothlypis peregrina), and especially Canada Warbler (Cardellina canadensis). Similarly, body condition improved across the season for Tennessee Warbler, Rose-breasted Grosbeak (Pheucticus ludovicianus), and Summer Tanager (Piranga rubra). Our results provided additional evidence that several common Neotropical migrants, including species of conservation concern such as Cerulean Warbler and Canada Warbler, may improve their body condition in shaded plantations. However, about half of the species assessed in this study did not show any significant improvement in their body condition (e.g. Red-eyed Vireo). Furthermore, on average, species were in poor condition (i.e. body condition scores were negative) in these coffee farms. Thus, the extent to which this agricultural system represents high quality habitat should be looked with caution. Overall, our data contribute novel information on daily patterns of body condition improvement for several common migratory birds in Andean shaded plantations.     

分段螺旋式甘草茎秆揉切装置设计与试验

针对全混合日粮饲草料揉切需求,该研究设计了一种分段螺旋式甘草茎秆揉切装置,对分段螺旋叶片的主体结构和搅龙结构参数进行设计,建立了刃口曲线方程,分析了装置揉切机理,并试制了分段螺旋式甘草茎秆揉切装置试验台。以搅龙转速、加工时间、填充系数、刀片与底壳间隙为因素,以粒度、破节率、单位质量能耗为指标,开展四因素三水平Box-Behnken试验,对试验结果进行方差分析和二次回归拟合,得出各因素对粒度影响显著性由大到小为加工时间、搅龙转速、填充系数、刀片与底壳间隙;对破节率的影响显著性由大到小为加工时间、填充系数、搅龙转速、刀片与底壳间隙;对单位质量能耗的影响显著性由大到小为填充系数、加工时间、搅龙转速、刀片与底壳间隙。对交互影响因素进行响应曲面分析并进行参数优化验证试验,结果表明:当搅龙转速为25 r/min、加工时间为12 min、填充系数为0.46、刀片与底壳间隙为15 mm时,甘草茎秆的揉切粉碎粒度为11.76 mm,破节率为83.27%,此时单位质量能耗为9 959.82 J/kg,试验值与模型理论值误差不超过7%,参数优化模型合理,满足作业要求。研究结果可为全混合日粮搅拌机的研发提供理...