THE TESTING OF GRASS VARIETIES IN SWARDS WITH CLOVER: THE EFFECT OF GRASS SEED-RATE ON COMPARISONS OF GROSS YIELD

Three experiments were carried out to examine the influence of grass seed-rate upon the amount of clover growing with different varieties of perennial ryegrass. The bred varieties S23 and S24 were compared with Irish ryegrass. A larger quantity of clover grew with Irish ryegrass than with bred varieties at any given seed-rate. If the varieties were to be compared in terms of herbage of similar clover content, then Irish ryegrass sown at 20 lb/ac had to be compared with S23 or S24 sown at about a quarter of that rate. Reducing the seed-rate of the bred varieties from 20 to 5 lb/ac had only a small effect upon yield of ryegrass, and this was offset by an increase in yield of clover. Since weed grasses also took advantage of low grass seed-rate, it is concluded that other factors in the management of variety trials must be so controlled as to produce a satisfactory clover content without too drastic a reduction in the seed-rate of any variety. The relationship between grass seed-rate and yield of clover varied markedly with the availability of moisture.     

马铃薯产量性状边际效应指数的相关分析

从马铃薯品种（系）边际效应指数入手,研究了马铃薯的产量边际效应指数与其它各主要农艺性状边际效应指数间的关系。结果表明,边际效应指数可以作为选择耐密马铃薯品种的指标。     

THE EFFECT OF METHOD OF SOWING ON THE ESTABLISHMENT OF GRASS SEED CROPS

Methods used by growers to establish seed crops of perennial ryegrass, cocksfoot, timothy and meadow fescue have been examined. While satisfactory establishments were obtained by sowing perennial ryegrass broadcast, cocksfoot, timothy and meadow fescue should be sown in rows, especially if they are to be sown under a cover crop.     

THE EFFECT OF THE GRAZING ANIMAL ON THE N STATUS OF GRASS SWARDS

Thirty-one sets of N yield data were considered, taken from seven experiments grazed by sheep. N yield could be explained in terms of fertilizer N rate, an estimate of soil N and an interaction between the two. Fertilizer N increased grass N yield more on grazed swards than on cut swards, and this effect was greatest on soils with high available soil-N. It is concluded that N recircula-tion can be substantial on heavily-stocked swards receiving high rates of fertilizer N, so increasing the efficiency of fertilizer as a source of N in these conditions.     

钾肥对向日葵增产潜力的影响

１９９０—１９９２年三年试验结果表明，尽管只施氮磷肥可获得高产，但在施氮磷肥的基础上按比例配施钾肥，可进一步提高向日葵的产量．钾肥的最佳经济施肥量为１５０公斤Ｋ２Ｏ／公顷，Ｎ、Ｐ２Ｏ６、Ｋ２Ｏ最适比例为２∶１∶２．     

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。     

黄腐酸对油菜生理和产量的影响

在开花期，用０、５０、１００和２００ｍｇ／ｋｇ黄腐酸溶液喷洒白菜型油菜（ＢｒａｓｓｉｃａＣａｍｐｅｓｔｒｉｓ），结果表明，黄腐酸能提高叶绿素含量，降低叶片电导率，提高叶片相对含水量，降低其水分饱和亏缺，从而增强了油菜抗旱能力．喷洒黄腐酸还显著提高油菜的干物质积累量和籽粒产量。     

THE EFFECT OF HEIGHT OF CUTTING ON THE SUBSEQUENT GROWTH AND YIELD OF LUCERNE

Three experiments designed to test the effect of height of cutting of lucerne on subsequent yield are described and the results discussed. Extremely low cutting, at ground level, can cause the death of individual lucerne plants, but if such extreme cutting is avoided there is no evidence to show any advantage in leaving a long stubble. In fact, in a sward, the lower the cutting the greater is the yield to be expected.     

THE EFFECT OF COMPANION GRASS AND SEED RATE ON THE PRODUCTIVITY OF A TALL-FESCUE SWARD

The effects of sowing from 10 to 50 lb/acre of tall-fescue seed on plant establishment and on the annual and seasonal distribution of DM yield of tall fescue and its companion grasses were measured through two growing seasons. Increasing the seed rate increased plant numbers per unit area and decreased per cent establishment. Adding Scots timothy as a companion grass depressed both plant number and per cent establishment. S37 cocksfoot and New Zealand perennial ryegrass reduced both still further. Total annual dry-matter production was relatively unaffected by varying either the seed rate or the companion grass. The contribution of tall fescue to total production was highest when sown alone and was successively reduced by timothy, perennial ryegrass and cocksfoot. When sown alone there were only slight differences in contribution of tall fescue due to seed rate. With any companion grass the contribution from tall fescue increased with increasing seed rate. Early growth was not reduced by modifying seed rate but was reduced by all the companion grasses. It is concluded that increasing the seed rate of tall fescue above 30 lb is not justified, that Scots timothy can be sown at 3 lb/acre with tall fescue without affecting total production or early growth of the mixture, with the advantages of control of unsown species and improved palatability of the herbage.     

THE EFFECT OF DRILL WIDTH ON THE SEED PRODUCTIVITY OF LEAFY VARIFTIES OF THREE GRASS SPECIES

Three leafy grass varieties, S215 meadow fescue, S37 cocksfoot and S51 timothy. were subjected to four dril spacings of 6, 15, 24 and 36 in. under two levels of nitrogen application. Over three harvest years, meadow fescue gave better seed yields with 6- and 15-in, drill spacings. Cocksfoot gave very similar yields from 1.5, 24- and 36-in, drills but a signincantly reduced yield from 6-in, spaced drills. Timothy produced significantly higher yields at the 24 in spacing.
The three varieties showed a significant response to nitrogen application.
Aphids seriously affected the vegetative growth of meadow fescue and timothy at the wider spacings, but the 6-in. drills m boths species remained relatively free of aphid attack, as also did the cocksfoot block.     

THE EFFECT OF INTRAVENOUS INFUSIONS OF METHIONINE ON THE VOLUNTARY INTAKE OF GRASS SILAGE BY SHEEP

The effect of intravenous supplements of L-methionine on the voluntary intake of a ryegrass silage, prepared using formic acid as an additive, was determined in a 4×4 Latin Square experiment with 4 sheep. Animals receiving no methionine consumed 1061 g DM/day; those receiving 0.8, 1.2 and 2.0 g methionine/day consumed 1015, 1012 and 1078 g DM/day. The concentration of methionine in blood plasma (Y; (_imoles/I) increased with the dose rate of methionine infused (X; g/day) such that Y=36.7 + 38.3X (r=0.80; P<0.001). It is concluded that with a diet of this type methionine may be limiting for protein synthesis in the tissues but is not involved in the control of food intake.     

大豆叶面积变化对田间微气象条件及产量的影响

作者通过1977～1981年和1987～1989年,分别在绥化、哈尔滨和合江地区的田间试验和生产调查,发现大豆叶面积指数的大小可造成不同的田间微气象环境条件,叶面积指数6左右时,植株似倒非倒,株间采光量和CO_2分布较为合理,光合效率高,大豆单株生育良好,群体产量高;在生产上可依据当地土地条件、施肥水平、不同品种和不同种植方式用叶面积动态变化方程式计算出适宜的密度,以使大豆群体最大叶面积指数保持在6左右,创造较理想的田间微气象效应。     

红壤施用石灰石粉对芝麻产量的影响

石灰石粉施用量的试验结果表明:(1)随着石灰石粉用量增加,土壤pH升高,交换性铝和铝饱和度下降。施后7年仍可发挥其效果。(2)施用石灰石粉,显著增加每株蒴数和千粒重,增产幅度为17％—6l％。(3)土壤pH升高到6.0以上、交换性铝含量降至1.0me/100克土以下,芝麻才能获得较高的产量。     

THE EFFECT OF HIGH LEVELS OF NITROGEN ON SEED YIELD OF COCKSFOOT (DACTYLIS GLOMERATA L.)

An experiment to determine the effect of applying high levels of N on the seed yield of S37 cocksfoot is described. Increasing the rate of application in the range 174–1044 Ib N/ac/annum did not substantially increase yield, except where 1044 Ib N was applied in monthly lots in 1960–1; in some instances yield was significantly reduced by increased N application, apparently as a result of increased frost susceptibility. It is concluded that an application of about 174 lb N/ac/annum is the maximum desirable if there is a danger of frost.     

大豆倒伏对植株性状和产量的影响

本文探讨了大豆倒伏对植株性状和产量的影响。指出了大豆倒伏临界冠/根比和倒伏临界期植株的干物质分配状况。经对倒伏和未倒伏植株的比较研究,结果表明,倒伏可以使株高明显增高,分枝减少,并使干物质分配在营养器官中的比例明显高于繁殖器官,最终导致荚重、粒重、百粒重、经济系数显著降低,产量约减少56％。     

THE EFFECT OF THE RATE AND TIMING OF NITROGEN APPLICATIONS ON THE SEED YIELD AND COMPONENTS OF YIELD IN S48 TIMOTHY (PHLEUM PRATENSE L.)

An experiment on the effect of the rate and timing of N applications on the seed yield of S48 timothy is described. Some benefits were obtained from the use of nitrogen, but the results were variable, probably because of the effect of the fertilizer on root size interacting with the currently prevailing climatic conditions. It is suggested that the adverse effect of dry weather during ear initiation and development might be alleviated by the use of irrigation.     

THE EFFECT OF SHEEP URINE ON THE GERIMINATION AND EARLY ESTABLISHMENT OF A COMMON WEED GRASS

Sowings of annual meadow grass ( Poa annua ) were made in pots of soil which had been treated with sheep urine, with urine diluted × 50, or with water as a control. The treatments were applied before, at, and after sowing.
Urine, whether applied at sowing time, or eleven days before or after, significantly reduced the germination or establishment of the weed grass.
Diluted urine tended to reduce the number of established seedlings when applied at or shortly after sowing.
In a subsidiary experiment the number of viable seeds in soil taken from pastures which had received no urine for four years were compared with those from soil under pastures receiving urine. The difference was not significant.