尿素及EDTA—Fe对高羊茅草坪草绿期的影响

在滨海盐碱地区，水分，盐分的胁迫，使草坪草体内矿质营养失衡，生长势减弱，在秋季即使轻微水分胁迫，都会使草坪草休眠提前，绿色期缩短，试验发现，秋冬季给高羊茅施用尿素或EDTA－Fe都可以改善其绿色度，增加叶片内叶绿素的含量，延迟草体进入休眠，并能加快春季返青的速度，但尿素和EDTA－Fe的交互效应在本试验中不显著。     

玉米青枯病的危害程度与密度、氮、磷关系的分析

本文采用二次回归通用旋转组合设计，研究了玉米青枯病的危害程度与播种密度（Ｘ１），施氮量（Ｘ２）和施磷量（Ｘ３）的关系，并组建了回归模型。结果表明，对玉米青枯病病指影响的首要因素是密度，其次是氮，对病指影响的交互效应是Ｘ１Ｘ２，Ｘ２Ｘ３。最后对模型进行模拟优化。     

The effects of nitrogen fertilizer rate, cultivation and straw disposal on the nitrate leaching from a shallow limestone soil cropped with winter barley

Abstract. Monoculture winter barley was grown for 5 years with 80 or 160 kg/ha of fertilizer nitrogen (N) and established by either shallow cultivation (straw removed) or ploughing (straw incorporated) in a replicated 2 ± 2 split plot experiment. The lower N rate reduced average grain yield from 6.85 t/ha to 5.61 t/ha. The cultivation/straw disposal system had no effect on yield. Halving the N rate reduced the amount of N removed in the crop by an average of 40 kg/ha and reduced the amount of nitrogen leached by 11 kg/ha per year. Using a shallow cultivation system for crop establishment, following the removal of straw, initially reduced N leaching compared to ploughing in the straw, but in the later years of the experiment losses were similar. Over the five years the full N rate with ploughing system resulted in a small positive nitrogen balance of 66 kg/ha, but all other treatment combinations resulted in a negative balance.     

Agricultural improvement of cultivated organic soils I. Effects of deep cultivation, liming, irrigation and P-fertilization on crop yields

Abstract. Four field experiments were carried out on cultivated shallow fen peat overlying acid gyttja (lake mud) soil. The accessibility of the generally ample supply of physically available water was restricted by a limited root depth caused by low pH and high levels of aluminium in the subsoil. In order to improve the nutrient status and the crop water supply of the soils liming, deep cultivation, P-fertilization and irrigation were tested in field experiments comprising these four main treatments and their combinations. Liming and P-fertilization of the topsoil, irrigation and deep cultivation in combination with deep liming improved crop yields. Deep cultivation without liming had a negative effect on yield in most years.     

尿素在青贮饲料中的应用

在描述反刍动物利用尿素机理的基础上,介绍了尿素青贮的作用、青贮饲料中的尿素用量、尿素青贮对青贮成分的影响以及尿素青贮对家畜生产性能的影响,并进一步指出了存在的问题。     

Pectinate ligament dysplasia and glaucoma in Flat Coated Retrievers. II. Assessment of prevalence and heritability

Pectinate ligament dysplasia (PLD) in dogs is a congenital ocular abnormality affecting the iridocorneal angle, the presence of which may be associated with adult-onset primary glaucoma. This study demonstrates a significant association between PLD and glaucoma in Flat Coated Retrievers, and also a higher prevalence of PLD in Flat Coated Retrievers compared with other breeds. It is shown that the association between PLD and glaucoma was robust and not due to a small increase in PLD with age. There was also a significant association between PLD in offspring and parents and, using the offspring–parents regression, the heritability of PLD was estimated as approximately 0.7. As glaucoma is significantly related to PLD, glaucoma may also be heritable. Thus, glaucoma can be controlled by gonioscopic examination and elimination of animals with a high degree of PLD from a breeding program. Breeding from only those animals with a moderate or low PLD value or score should limit the expected prevalence of glaucoma in the resulting population to < 0.2%. The preceding study describes in detail the PLD survey, gonioscopic technique and some initial results obtained prior to this epidemiological investigation.     

Integrated Control of Powdery Mildew on Field-grown Mango Trees by Foliar Sprays of Mono-potassium Phosphate Fertilizer, Sterol Inhibitor Fungicides and the Strobilurin Kresoxym-methyl

Foliar sprays of solutions of di-potassium hydrogen orthophosphate, K2HPO4 (DKP) and potassium di-hydrogen orthophosphate, KH2PO4 (MKP), commercial systemic fungicides, and an alternating treatment with phosphate fertilizer and systemic fungicides inhibited development of the powdery mildew fungus, Oidium mangiferae, on flowers and bloom clusters of field-grown mango trees. The effectiveness of the alternation treatments with an appropriate systemic fungicide and 1% solution of mono-potassium phosphate (MKP) in controlling powdery mildew on bloom clusters was similar to that of the commercial treatment with the systemic fungicides. However, application of the systemic fungicides alone, on the same dates on which they were applied in the alternation treatment, without application of the phosphate treatment was significantly less effective in controlling the disease than either the phosphate or the alternation treatment. This indicates that the use of phosphate fertilizer has a significant role in disease control and that it can reduce the number of fungicide treatments necessary against powdery mildew by up to 50%. These results were confirmed in large-scale demonstration trials conducted in commercial orchards in 1994 and 1995. Our 1997 findings also revealed that tank-mix treatments of 1% MKP solution with half the recommended quantity of sterol inhibitor fungicide applied at 14-day intervals provided a protection against powdery mildew comparable with or superior to that given by the standard fungicides-based treatment applied at 7-day intervals. Tank-mix treatments of MKP (1%) with sterol inhibitor at the recommended rate or with the new strobilurin Kresoxym-methyl (BAS 490F, strobi), or the BAS 490F alone, were the most effective, and provided >95% protection against O. mangiferae, compared with the control. Phosphate solutions were found not to be phytotoxic to plant tissue. These treatments affected the yield of mango trees: a significantly lower yield was observed on control untreated trees, probably because of powdery mildew infection on flowers. The inhibitory effectiveness of phosphate salts makes them a potential major component of an integrated pest management program.     

豆粕、尿素与玉米秸秆间的组合效应

作者用体外法研究玉米秸秆和不同氮源的组合效应,尿素和豆粕分别作为主要氮源,玉米秸秆为主要纤维源,根据体外产气量和消化率评价反刍动物日粮中中性洗涤纤维(NDF)和粗蛋白质(CP)间的组合效应。结果表明,培养24 h,豆粕组饲料蛋白质水平为9%~18%时均呈现显著正组合效应（P＜0.05）,当饲料蛋白质水平为15%时气体产量最高（P＜0.01）;尿素组的组合效应在CP水平为8%～15%的范围内达到显著（P＜0.05）,CP水平为12%时效应值最高（P＜0.01）。     

Bio-efficiency of compost extracts on the wet rot incidence,morphological and physiological growth of okra (Abelmoschus esculentus [(L.) Moench])

An experiment was carried out to investigate the efficacy of rice straw and empty fruit bunch (EFB) of oil palm compost extracts either fortified or unfortified with Trichoderma harzianum on morpho-physiological growth and occurrence of Choanephora wet rot of okra. Treatments tested were water (control) (T1), rice straw (RST) compost extract (T2), Trichoderma-enriched RST compost extract (T3), empty fruit bunch of oil palm compost extract (T4), Trichoderma-enriched EFB compost extract (T5), aqueous suspension of Trichoderma (T6), and a fungicide Dithane M-45^® (2 g l⁻¹ of water) (T7). The experimental results revealed significant variations amongst the treatments in respect of morphological characters, e.g. shoot length, tap root length, number of leaves per plant, and leaf area. The shoot and tap root length, number of leaves per plant, leaf area were significantly (P ≤ 0.05) higher in Trichoderma-enriched RST compost extracts (T3) followed by Dithane M-45^® (T7), Trichoderma-enriched EFB extracts (T5), RST (T2), EFB (T4) and aqueous suspension of T. harzianum (T6) in both Choanephora inoculated and uninoculated (control) plots. Similarly, net photosynthetic rate and chlorophyll content were higher in plants receiving Trichoderma-enriched RST compost extracts (T3) with 76.2% reduction in Choanephora wet rot incidence when compared with rest of the treatments. These experimental results revealed that morpho-physiological characters of okra could be modified by the application of Trichoderma-enriched compost extracts. This suggests that use of Trichoderma-enriched compost extracts would be more beneficial in environmentally friendly okra cultivation and may be used as an alternative to inorganic fertilizers/fungicides to enhance plant growth and reduce disease incidence subsequently, resulting in higher yield.     

川西北围栏草地氮、磷、钾肥效应研究

川西北草地由于超载放牧极其严重,草地质量退化迅速.为了维持草地的可持续发展,以围栏草地为研究对象,采用氮、磷、钾三因素不完全试验设计与裂区试验设计相结合的方法,探索防止草地退化的施肥技术.结果表明,速效氮、磷肥的施用能显著增加牧草产量.连续2年施用N90和P30比不施肥增产265.3%;第2年连续施肥比第2年不施肥相对增产40%～135%;第1年施肥处理的肥料后效比不施肥处理平均增产112.3%;干草产量随施氮量和施磷量的增加而增加,呈正直线相关;钾肥在该草地上没有表现出增产效果.氮肥能显著提高围栏草地品质,高氮处理(N135)比无氮处理(N0)粗蛋白含量增加20%以上.综合产量和品质两方面因素,川西北草地最佳施氮量为135～150 kg/hm2,最佳施磷量为15～30 kg/hm2,而钾肥可以不施;在最佳氮、磷肥配施下,可以采用隔年施肥来降低成本,增加经济效益.