THE RELATIONSHIP BETWEEN INTENSITY OF GRAZING AND THE HERBAGE CONSUMPTION AND GROWTH OF CALVES

Experiments were conducted in 1967 and 1968 in which HerefordXFriesian (Experiment 1) and Friesian (Experiment 2) steer calves horn in April were turned out to graze at one week or 3 months of age, respectively, and maintained at three stocking densities in the ratio 1:2:3 animals per unit area. The calves grazed paddocks of S23 perennial ryegrass in rotation, and were moved when the height of grazed stubble at the medium stocking density was reduced to 8 cm. The rate of liveweight gain and herbage intake per head declined as stocking rate increased. When the results of the two experiments were compared, the weight gain of the calves was more closely related to the weight of herbage residues than to the height of the grazed sward. The rate of liveweight gain was depressed when the amount of herhage left after grazing fell helow 2000–2500 kg OM/ha (1800–2250 Ib/ac).     

甘蓝型油菜雄性不育系与可育系花蕾的生理生化特性

试验结果表明，油菜雄不育系在花粉母细胞减数分裂期，花蕾ＡＢＡ含量显著高于相应可育系；ＧＡ含量显著低于相应可育系；ＲＮＡ含量高于或低于相应可育系．在单胞期后，ＲＮＡ与ＧＡ含量显著低于相应可育系。外源ＧＡ、ＡＢＡ对不同的不育系影响不同。随着花蕾的发育，雄不育系游离脯氨酸逐渐降低，部分可育的不育系有一定积累，正常可育系则有大量积累；天门冬氨酸、苏氨酸、谷氨酸、丙氨酸降低；不育花蕾与可育花蕾的天门冬氨酸比值由低变高；不育花蕾与可育花蕾半胱氨酸差异显著。     

THE EFFECT OF PHOTOPERIOD AND TEMPERATURE ON THE RELATIONSHIP BETWEEN THE ROOT AND SHOOT SYSTEMS OF LOLIUM PERENNE

In controlled environment cabinets, root growth relative to shoot growth varied directly with the temperature within the range 50·–80·F. Increasing the photoperiod from 6 to 12 hours increased the root growth relative to shoot growth; additional hours of light had no further influence on this ratio. These results are discussed in relation to the maintenance of a balance between photosynthesis and the absorption of water and minerals.     

菜用大豆荚皮性状与产量形成的关系

利用菜用大豆的四个杂交组合,对其荚皮性状即荚皮的长、宽、表面积以及荚皮的内膜层、革质层等性状进行试验观察,并分别与子粒、产量进行相关分析.荚皮的长、宽、表面积、荚皮内膜层、荚皮革质层与产量有极显著正相关,荚皮表面积与产量的相关系数达0.6795**,内膜层鲜重与产量的相关系数和通径分析均达到0.8433**.革质层与子粒的相关性较大,百荚革质层的鲜重、风干重与百粒重的相关系数达0.6681**、0.6112**,荚皮厚与子粒鲜、干重及产量均呈极小不显著的正负相关(-0.0706～0.2810).在育种工作中应重视荚皮的表面积、内膜层和革质层等对产量和产品质量的影响.     

高效液相色谱法测定大豆中的维生素E含量及其与粗脂肪含量的线性回归分析

利用高效液相色谱法测定1000份大豆资源中的维生素E含量,使用荧光检测器检测(Ex=295nm,Em=330nm),以α-、β-、γ-、δ-生育酚为标准品,加入母育酚为内标,计算大豆中维生素E各异构体的含量及总含量,α-、β-、γ-、δ-生育酚的加标回收率分别为101.10%、97.50%、96.94%和96.30%,测得野生大豆资源中维生素E含量范围0.05～0.34mg/g,栽培资源0.12～0.38mg/g.同时按国标方法测定粗脂肪含量,其中野生资源粗脂肪含量范围3.01%～20.60%,栽培资源12.00%～23.59%.通过线性回归分析,明确了大豆中维生素E与粗脂肪含量呈正相关的线性关系.     

THE EFFECT ON THE SOIL OF THE COMPONENTS AND MANAGEMENT OF A LEY

The effect of four grasses, and four methods of utilizing the herbage, on the root weight, the proportion of organic matter in the soil and the water-stability of the soil aggregates was measured over a period of three years. The grass species in the sward had a greater effect upon the measurements than had the methods of management. Of the grass species, Lolium perenne produced the greatest root weight and highest percentage of organic matter in the soil.     

THE EFFECT OF THE TIME AND LEVEL OF INJECTION OF ANHYDROUS AMMONIA ON THE PRODUCTIVITY OF GRASSLAND

Four levels of nitrogen, 188, 285, 358 and 392 kgJ.ha (150, 225, 285 and 350 units/ac) supplied as anhydrous ammonia were injected on each of four occasions, 18 Dec, 5 Feb., 12 Mar. and 16 Apr. DM and CP yields were estimated at each of three harvests taken on 4 June, 19 July and 28 Sept Total DM yields showed only a 10% difference between the highest yielding injection date, 12 Mar., which yielded 12270 kg/ha (10946 Ib/ac) and the lowest, 16 Apr., which yielded 11169 kgJ.ha (9963 Ib/ac). Early injection of ammonia promoted growth during the late spring and later injections resulted in increased yields at the two later harvests. The responses per kg fertilizer N were 11.9 kg DM (10.8 lb/unit) and 3.6 kg CP (3–3 Ib/unit). It was concluded that ammonia should be applied to grassland before April and, preferably, during March, for maximum yields of DM and CP.     

光周期对马铃薯块茎形成的影响及对激素的调节

马铃薯出苗后接受１个月的每日８小时短日照处理并与当时自然光照长度进行比较，研究光照长度对块茎形成及内源激素②的影响，探讨块茎形成与激素水平的关系。结果表明：短日照处理使块茎形成显著提早，但使结薯数减少，植株茎叶生长受抑，块茎淀粉含量降低；短日照处理使叶片中ＡＢＡ含量提早增高，ＧＡ３含量提早减少，ＧＡ３与ＡＢＡ的比值提早显著降低．     

COMPETITION BETWEEN WHEAT AND UNDERSOWN PASTURE IN THE YEAR OF SOWING AND THE EFFECT OF UNDERSOWING ON THE YIELD OF PASTURE IN THE FOLLOWING YEAR

Sowing pasture species with wheat caused a reduction in the growth and yield of the pasture species. This reduction was more severe with wheat drilled at 7 inch row spacing than at 14 in., and was least when the two crops were in alternate 7 in. rows. The reduction appeared to be due principally to the shade cast by the wheat. The pasture also reduced the growth and yield of wheat, but the effect of row spacing and position were opposite to and very much less marked than those of wheat on pasture. The yield of the pasture early in the following season was related to the seed yields in the year of establishment; later in the season, however, differences in yield among the various treatments disappeared.     

营养液对马铃薯微型薯数量及产量的影响

为探索营养液的成分及浇灌次数对微型薯的数量及产量的影响,设计了3种营养液成分A_1,A_2,A_3和3种浇灌次数B_1(两天浇1次),B_2(4天浇1次),B_3(6天浇1次)。研究结果是:选择A_2营养液,每4天浇1次或6天浇1次就可达到低成本、省工、省力、薯块数量多、产量高、大中薯率高的优质脱毒微型薯。     

NAA和2,4-D对脱毒马铃薯扦插苗生长及产量的影响

本文研究了不同浓度NAA和2,4-D配合使用对马铃薯扦插苗的生根、生长及产量的影响。结果表明,6种处理中,其中浓度为NAA5mg／l,2,4－Dlmg／l的处理扦插苗生根数多,成活率高,植株长势强,产量最高。     

花生种子子叶和胚轴发育的差异性及活力的形成

发育中的花生种子子叶和胚轴在内源ＡＢＡ含量和贮藏蛋白合成等方面均有明显的差异性．子叶的发育与种子萌发能力形成有密切关系，胚轴的发育和种子活力的提高高度相关．子叶内存在ＡＢＡ的Ｃ４０途径，胚轴内存在Ｃ１５途径，随着种子的发育，胚轴ＡＢＡ含量迅速提高并可能向子叶转移，ＡＢＡ促进了贮藏蛋白质的合成．     

THE DISTRIBUTION OF CARBOHYDRATES, NITROGEN AND LIGNIN IN SOLUBLE FRACTIONS OF THE STEMS AND LEAVES OF LUCERNE HAY

The nitrogen-free extractive (or soluble carbohydrate) and total nitrogen contents of the stems and leaves of lucerne hay were separated into three fractions, soluble in (a) 90% ethanol, (b) cold water, and (c) acid + alkali of the same concentrations as used in the crude fibre determinations. Total and "soluble" lignin contents were also determined.
The soluble carbohydrates in the stems comprised a lower proportion of the simpler types (90% ethanol soluble) and a higher proportion of a more complex nature (acid + alkali soluble) than in the leaves. The differences between the 90% ethanol soluble fractions were not due to the sugars but to unidentified materials which would include oligosaccharides, acids, saponins and possibly other constituents of an unknown nature.
The lignin content of the stems was more than three times that of the leaves, but, in both parts of the plant, the amount of "soluble" lignin was small.
In the stems, "protein" nitrogen constituted a lower proportion of the total nitrogen, and was possibly of a less digestible type than that in the leaves.
These results added emphasis to the importance of preventing leaf loss during the conservation of lucerne hay, not only to prevent actual loss of material but also in order to preserve its nutritive value.     

THE EFFECTS OF CUTTING AND FERTILIZER TREATMENTS ON THE YIELD AND BOTANICAL COMPOSITION OF CHALK TURF

Annual factorial applications of N and K fertilizers, with or without mowing, to Festuca rubra turf on a chalk rendzina at Swyncombe, Oxon, had large effects on yield and botanical composition over a period of 10 years. The yield of herbage was increased markedly hy N, and less by K, but the N × K interaction was significant. Mean yields of herbage DM for tbe 10-year period were: no N or K, 730 kg/ha per year; N, 1967; K, 1013; N+K, 2794 kg/ha per year (651, 1755, 904 and 2492 lb/ac per year). N caused an increase in DM production by F. rubra; the NxK interaction was a result of increased growth of species other tban F. rubra. Unmown plots became extremely matted, and undecomposed litter of F. rubra leaves and stems accumulated, especially if N, or N and K together, were given. F. rubra turf seems to he unusually stable, apparently because it forms a mat in which other more demanding species cannot establish themselves.     

麦套夏花生生育特点及干物质积累分配规律的研究

麦套花生，苗期生长慢、时间长，开花、下针、幼果形成集中，具有较长的产量形成期；主茎高度、总干物质和荚果干重增长规律符合“Ｓ”型生长曲线，可用Ｌｏｇｉｓｔｉｃ方程ｙ＝ｋ／（１十Ａｅ－Ｂｘ）很好拟合；叶面积消长动态符合一元二次方程变化曲线；总干物质积累速率高峰在结荚期（播种后８１天），荚果干重增长速率高峰在播种后９５天，整个产量形成期内荚果干重日增量都保持较高水平，后期不早衰，且具有较高的分配系数。     

花生种子蛋白酶活性与种子活力的关系

发育中的花生种子存在着ＢＡＰＡａｓｅ活性，当由发育转向萌发时，活性迅速提高，蛋白酶活性随着种子成熟度的提高而增大。在萌发过程中没有新的蛋白酶合成。ＡＢＡ抑制了蛋白酶的活性。劣变的花生种子中，其蛋白酶活性显著降低。