有机微量元素对奶牛体细胞数、产奶量和趾蹄健康的影响

在靠近弗罗里达Jacksonville附近的一所牧场里选择354头奶牛，于夏季实验。将奶牛分为4组，两组头胎牛，两组经产牛。试验目的在于研究蛋白质螯合Zn、Mn、Cu（选用奥普明ZMC产品，Trouw Nutrition USA公司）对于奶牛产奶量、乳体细胞数、趾蹄健康的影响。研究结果发现乳中体细胞数对照组奶牛超过10万/mL，而试验组的体细胞数则很低，二者差异极显著（P〈0．01）。奥普明产品对产奶量的影响异不显著，部分数学模型表明奥普明ZMC对提高产奶量有效，但其它模型则未见效果。评测手段的原因导致不能做出对奶牛的趾蹄健康评分的影响。     

The control of rotting and browning of litchi fruit by hot benomyl and plastic film

Browning, weight loss and rotting of litchis (Litchi chinensis Sonn) were studied in 3 seasons with fruit from several growing-areas in Australia. Post-harvest wastage was reduced when the fruit were dipped in hot benomyl and packed in plastic film. A benomyl dip (0.05% at 52°C for 2 min) followed by packing the fruit in punnets and over-wrapping with a “cling” pvc film (0.01 mm thickness) is suggested for controlling rotting, browning and loss in weight at temperatures of 20–30°C.     

Integrated control of grape black rot: influence of host phenology, inoculum availability, sanitation, and spray timing

ABSTRACT The epidemiology and control of black rot (Guignardia bidwellii) was studied from 1995 to 1999 in vineyards in Dresden and Naples, NY, where disease pressure was moderate and extreme, respectively. The efficacy of serial applications of myclobutanil, provided at 2-week intervals and varied with respect to their number and time of initiation, was examined within the context of host phenology, inoculum availability, and sanitation. At Dresden, sprays applied over 4 weeks through the immediate prebloom stage provided only 13 to 91% control of diseased clusters, despite the release of 95% of the season's ascosporic inoculum during the period of fungicidal protection. However, applications immediately prior to bloom plus 2 and 4 weeks later, which afforded protection while fruit are highly susceptible to infection, provided virtually complete control. At Naples, where mummified berries were retained in the canopy after mechanical pruning, this same regime provided only approximately 80% disease control, but applying a fourth spray 2 weeks prebloom generally improved control. Hand-pruning mummies to the ground in selected plots significantly (P 相似文献   

The use of an alternative food source (red clover) as a means of reducing slug pest damage to winter wheat: towards field implementation

Slugs are major pests of many crops in the UK, including winter wheat, yet current methods of control are often unreliable. The aim of this study was to investigate three issues key to the successful field implementation of a control strategy that uses red clover as an alternative food source to reduce the amount of damage caused to winter wheat by the field slug, Deroceras reticulatum (Müller). A series of three experiments was designed to assess this aim. Firstly, under laboratory conditions, red clover was consumed in greater quantities than wheat, even when wheat was presented as a novel food. Secondly, red clover had no significant effects on the emergence and early growth of wheat in a polytunnel experiment. Both these results are crucial to the successful implementation of a strategy that uses red clover as an alternative food source. Lastly, the results of a field experiment were consistent with the results of the polytunnel experiment, in that red clover did not significantly affect wheat emergence. However, plots in which red clover was left to grow until the time of wheat harvest resulted in significantly lower (43%) wheat yields than plots without red clover. These results suggest that red clover must be removed from the field after the wheat has passed its vulnerable seedling stage. Recommendations for the potential use of red clover as an alternative food source for reducing damage to winter wheat in field conditions are discussed and opportunities for further work are suggested.     

Establishing sorption isotherm to meet phosphorus requirement for tomato seedling growth 1

An Indiana silt loam soil was equilibrated with various amounts of Ca(H₂PO₄)₂ H₂O and a 0.01 M CaCl₂ solution to construct its phosphorus sorption isotherms. Using the isotherms, the P buffering capacity of the soil was calculated and amounts of fertilizer P necessary to give several levels of P in the soil solution, for experiments conducted over a 2 year period, were determined. Twenty‐four day old tomato seedlings were grown and measured for leaf area, root length, dry weights and P concentrations in leaf, petiole, stem and root.

Phosphorus concentration in soil solution increased slowly with the first increment of P added to the soil. Subsequent P additions increased the P concentrations in solution exponentially. The maximum P absorption by the soil was 324 μg P/g soil and the constant related to P binding energy was 1.37. In addition, the soil buffering capacity decreased with an increase in the amount of P in the soil solution.

Plant shoot dry weight increased linearly with P increase in the concentration range 0.65 to 6.5 μM P in soil solution. However, beyond this level the response was low. The leaf area rate of increase in the 0.65 to 6.5 μM P solution concentration range was 75 times that in the 6.5 to 84 μM P. The root length: shoot dry weight ratio decreased with increasing P supply in the soil solution. P uptake by the plants increased with increased P concentration in soil solution. At soil solution concentrations above 6.5 μMP the rate of P uptake in the shoot was 20 times less than the rate for concentrations below 6.5 μM P. Of the P taken up by tomato seedlings about 65% was in the leaf, 13% in the stem, 13% in the petiole and 9% in the root.