首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 68 毫秒
1.
Seed crops of perennial ryegrass S321 and tetraploid hybrid ryegrass Sabrina were sprayed with 3 pt diquat in 30 gal. water/ac (4.21 diquat in 337 1 water/ha) a few days before the normal date for harvest. Very low germination values were obtained wben the harvested seed was later tested and the production of abnormal seedlings from the treated crops was attributed to the presence of diquat in the seed. On the basis of these results the use of diquat is not recommended as a pre-harvest desiccant for ryegrass seed crops.  相似文献   

2.
Ten Certified Seed lots of S23 perennial ryegrass produced in different counties in England during 1966, and ten lots produced in 1972, were examined for differences in characters affecting seed quality. The 1966 seed lots differed significantly in 1000–seed weight, germination rate, N content of the seed and seedling dry weight, and there was a significant correlation between seed N content and the seedling weight of the progeny. In both S23 and S24 perennial ryegrass N applied at inflorescence emergence or at anthesis increased N content of the seed and seedling dry weight. In S24 application of N at anthesis increased 1000–seed weight also. When plants of S23 perennial ryegrass were subjected to reduced moisture supplies their seed N content was increased. It is concluded that late N applications to grass seed crops may affect seed quality.  相似文献   

3.
Perennial ryegrass ( Lolium perenne L.) is one of the most valuable temperate pasture grasses in the world. Understanding seed germination in response to temperature can help determine its optimal seeding times. Germination tests for two cultivars of perennial ryegrass (cv. 'Turfstar' and cv. 'Transtar') were conducted by applying thirty-six constant and alternating temperature regimes, ranging from 5 to 40°C (16 h night/8 h day). Responses in germination rate to these temperature regimes were then used to construct a quadratic response surface, giving estimated germination rates with confidence intervals at P  ≤   0·05 for both cultivars. Optimum germination rate occurred over a range of regimes: 15/25, 20/25, 20/30 and 25/30°C. Furthermore, a wide range in diurnal alternating temperatures resulted in maximum seed germination rate for cv. 'Transtar', while no constant temperature regime supported maximum germination rate for cv. 'Turfstar'. A temperature-dependent germination rate function for perennial ryegrass was developed which could be used in the future to predict location-specific optimum seeding times when national or regional monthly temperature data are available.  相似文献   

4.
Italian ryegrass cv. Leda and perennial ryegrass cv. Presto were sown alone and in five mixtures containing different proportions of viable seed and compared with hybrid ryegrass cv. Manawa and Italian ryegrass cv. S22. Yields and herbage composition were measured five times in 1962 and 1963, with particular reference to the contribution from perennial ryegrass in the first year and the effects of Italian ryegrass on second-year production. Italian ryegrass dominated first-year production wbile perennial ryegrass dominated second-year production. Manawa was the top yielder in the first year, but both Manawa and S22 bebaved as Italian ryegrasses and were badly frosted and weedy in the second year. The mixtures were generally intermediate in yield between the components and tended towards the yield of the more vigorous component. Since the more vigorous component changed from cut to cut or from season to season, the sums of harvests sbowed some advantage for certain mixtures. Certain pairs of herbage varieties can be sown togetber witb yield advantage. Furtber physiological investigations are warranted and the breeder has a part to play in a search for complementary varieties.  相似文献   

5.
The persistence of atrazine, prometon and a 1:3 mixture of metolachlor with terbuthylazine was studied under field conditions for 3 years in a semi-arid tropical climate. Each product was applied at recommended and double doses as pre-emergence treatments. The persistence of these herbicides was assessed both by bioassay techniques using crops commonly grown in Zimbabwe and by chemical analysis of the soil. At recommended doses the metolachlor plus terbuthylazine mixture did not cause any crop phytotoxicity in all three seasons whereas at double dosage it caused phytotoxicity in two of the three seasons. Atrazine at recommended doses was slightly phytotoxic in one of the three seasons whereas at double the dose it caused slight injury in two of the three seasons. Prometon caused slight injury in two of the three seasons at both doses. All injury symptoms from these herbicides were soon outgrown and the crop grain yield was not adversely affected. A leaching experiment was also carried out in the laboratory for 2 years using polyvinyl chloride (PVC) pipes. In these experiments atrazine was leached down to 40 cm, with most injury to the tested plants occurring in the top 25 cm of the soil profile. Chemical analysis of the soil revealed that residues of the three herbicides were still found in the soil 12 months after application, but in small amounts which did not cause crop yield reductions.  相似文献   

6.
Asulam applied in April 1981 and 1982 gave good control of established plants of Bromus sterilis growing in Italian and perennial ryegrass crops grown for seed. Doses of 1–3 kg a.i./ha reduced numbers of weed inflorescences by 65–90%. The results also showed that there was no effect on crop heading and further suggested that seed yield had not been reduced. Two pot experiments also indicated the efficacy of asulam at 0·5-2 kg a.i./ha applied pre-emergence and further study of such treatment in the autumn during the establishment of a ryegrass seed crop is warranted.  相似文献   

7.
SEED PRODUCTION STUDIES ON PERENNIAL RYEGRASS, TIMOTHY AND PRAIRIE GRASS   总被引：4，自引：0，他引：4  
This paper considers the sequence of seed development by measurement and observation of ehanges in seed moisture content, weight, colour, endosperm consistency, germination capacity and yield in perennial ryegrass Grasslands Ruanui, timothy Grasslands Kahu and a New Zealand strain of prairie grass (Bromus unioloides). Seed moisture content was high (60–70%) after anthesis and declined at different rates, depending on the species and the weather. Maximum seed dry weight (maturity) was reached approximately 30 days after peak anthesis in all species and was influenced by N application and grazing. Colour changes in the seedhead and endosperm solidification proved unsatisfactory as measures of maturity. Endosperm solidification was reached 4, 11 and 12 days before maximum seed dry weight in ryegrass, timothy and prairie grass, respectively. Seeds removed from the plant as little as 7, 10 and 4 days after anthesis in ryegrass, timothy, and prairie grass, respectively, germinated, provided that dormancy was broken; but they did not retain viability after 3 months storage. Maximum viability of ryegrass, timothy and prairie grass seed tested immediately after harvest occurred 30, 38 and 16 days after anthesis, compared with 17, 35 and 12 days, respeetively, when germination testing was delayed for 3 months. In ryegrass, grazing caused a significant increase in seed yield in the second year while N application alone did not significantly increase yield. In timothy, grazing and to a lesser extent N, were both detrimental to seed yield in the second year. Highest yields were obtained in treatments not receiving either grazing or N. In prairie grass, grazing depressed and N application increased yields in both years. In all species similar or increased yield could be obtained by mowing the crop at, or slightly prior to, seed maturity and allowing seed development and ripening to continue on the cut straw for up to 10 days. Using this technique higher seed yields were obtained in ryegrass and timothy than when seed was direct-harvested. In prairie grass similar yields were obtained whether the erop was direct-harvested or threshed following drying in the swath for 10 days. The use of ‘drying curves’ for the prediction of correct cutting time of seed crops is suggested for ryegrass, timothy and prairie grass.  相似文献   

8.
Four two-year field trials, arranged in randomised split-plots, were carried out in southern Sweden with the aim of determining whether reduced N fertiliser dose in winter wheat production with spring under-sown clover cover crops, with or without perennial ryegrass in the seed mixture, would increase the clover biomass and hence the benefits of the cover crops in terms of the effect on the wheat crop, on a subsequent barley crop and on the risk of N leaching. Four doses of nitrogen (0, 60, 120 or 180 kg N ha−1) constituted the main plots and six cover crop treatments the sub-plots. The cover crop treatments were red clover (Trifolium pratense L.), white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.) in pure stands and in mixtures. The winter wheat (Triticum aestivum L.) was harvested in August and the cover crops were ploughed under in November. The risk of N leaching was assessed in November by measuring the content of mineral N in the soil profile (0–30, 30–90 cm). In the following year, the residual effects of the cover crops were investigated in spring barley (Hordeum distichon L.) without additional N. Under-sowing of cover crops did not influence wheat yield, while reduced N fertiliser dose decreased yield and increased the clover content of the cover crops. When N was applied, the mixed cover crops were as effective in depleting soil mineral nitrogen as a pure ryegrass cover crop, while pure clover was less efficient. The clover content at wheat harvest as well as the amount of N incorporated with the cover crops had a positive correlation with barley yield. Spring barley in the unfertilised treatments yielded, on average, 1.9–2.4 Mg DM ha−1 more in treatments with clover cover crops than in the treatment without cover crops. However, this positive effect decreased as the N dose to the preceding wheat crop increased, particularly when the clover was mixed with grass.  相似文献   

9.
Leafy strains of five grasses were grown for seed and subjected to various cattle grazing treatments between October and April for three harvest years. The grasses were: S.143 cocksfoot, S.215 meadow fescue, S.170 tall fescue, S.59 red fescue and S.23 perennial ryegrass. All but S.59 red fescue (row crop) were studied as row and broadcast crops. The plots were sown under an arable silage crop and received top dressings of nitrogenous fertiliser every year. Yield of seed, and also quantity of herbage in winter, were measured.
October grazing in the seeding year reduced the first crop of seed in all species except ryegrass. Grazing in December improved the yield of meadow fescue throughout the experiment, and of cocksfoot, tall fescue and red fescue after the first year. Several factors might operate to bring about this effect; suggestions are made for further investigation. Repeated grazing from December to March tended to reduce vigour, and so to offset the advantage of removing autumn-grown herbage. Grazing at intervals from December to late April seriously reduced yield in all species. Tall fescue and red fescue, early flowering species, were most seriously affected, meadow fescue and perennial ryegrass least. Cocksfoot and tall fescue yielded more seed when grown in 2-ft. rows than when broadcast. Meadow fescue and perennial ryegrass did not. The yield of meadow fescue was less affected by adverse conditions than cocksfoot.  相似文献   

10.
Field experiments were conducted in 2010 and 2011 in a typical location of North China Plain to evaluate weed control efficacy of four post-emergence herbicides nicosulfuron, mesotrione, topramezone and the combination of mesotrione/nicosulfuron when they were applied at reduced doses at different weed growth stages. Experimental results showed that nicosulfuron, topramezone and the combination of mesotrione/nicosulfuron provided better weed control efficacy than mesotrione when they were applied at their label recommended doses at the 2- to 3-leaf and 4- to 5-leaf stages of weeds; nicosulfuron and mesotrione/nicosulfuron could at least be reduced by 33% and topramezone reduced by 67% without sacrificing total weed control efficacy and maize grain yield. Nicosulfuron and its combination with mesotrione could effectively control broadleaved and grass weeds when their doses were reduced by 67% and by 33%, respectively. Topramezone could effectively control broadleaved and grass weeds when its dose was reduced by 67%. The efficacy of mesotrione in controlling grass weeds was bad even at the label recommended dose. All four herbicides tested did not affect the maize grain yield.  相似文献   

11.
A leafy strain of timothy and of perennial ryegrass showed no significant reductions in seed yields following grazing at different dates from October to January, when extra nitrogen was applied.
Spring and winter + spring grazing, together with extra nitrogen, significantly reduced the seed yield of S50 timothy for three successive harvest years.
Perennial ryegrass S101 showed no reduction after spring or winter + spring grazing when defoliation was made not later than mid-April, but when grazing was delayed until May and drought occurred there was a significant reduction in seed yield.  相似文献   

12.
Perennial ryegrass/white clover swards have some limitations in temperate grazed dairying systems. This study tested the hypothesis that farmlets based on alternative species would be equally or more profitable than those perennial ryegrass‐based, and would produce more herbage in summer‐dry conditions. Six farmlets were established; three with perennial ryegrass‐ and three with tall fescue‐based swards. For each grass species, one farmlet was solely based on grass‐clover swards while the other two had either chicory‐red clover or lucerne crops planted on 20%–25% of the area. Animal‐ and herbage performance‐related variables were measured for 3 years, and calculated financial performance was evaluated. Using tall fescue improved total annual herbage yield compared with perennial ryegrass, but animal production and operating profit were lower. This was likely due to the reduced yield and nutritive value of tall fescue during spring and an associated decline in daily milksolids production. The deficit in spring milksolids production was never recovered, despite greater herbage production from tall fescue during summer/autumn. Incorporating chicory‐red clover or lucerne crops reduced both annual herbage and milksolids production. This reduced farm income, while increasing operating expenses as the farmlets required crop renewal and more purchased supplementary feed to maintain feed supply. Under the conditions of this study (i.e., partial irrigation, high nitrogen supply), changing the forage base from perennial ryegrass to tall fescue did not improve animal production or profitability, nor did incorporation of crops on 20%–25% of the farmlet area.  相似文献   

13.
This investigation was carried out with leafy varieties of perennial ryegrass at four centres near Aberystwyth over a period of three years. Nitrogen applied in spring increased lodging, the number of fertile tillers and also seed yield, except where sowing was made without a cereal cover crop. While reasonable yields were obtained from badly laid crops, it is suggested that lodging prior to anthesis has an adverse effect on seed yield. Clover included as a companion species tended to depress the yield of seed and increase the degree of lodging.
Seed rate had less infiuence on lodging and seed yield, but the data show that similar yields were obtained from light seed rates of 4 lb. per acre as from the heavier rates. On the other hand, there was a tendency for the low rate of seeding to produce weedy plots, especially when sown in the absence of a cover crop.  相似文献   

14.
Field studies were conducted in 2007 and 2008 at Hamilton Farms near Lonoke, Arkansas, USA to evaluate the potential impact of sub-lethal doses of glyphosate and glufosinate on winter wheat (Tritium aestivum). Three wheat cultivars were seeded, and glyphosate and glufosinate were applied at 1/10 and 1/20 times the labeled dose at the 3- to 4-leaf, panicle initiation, and boot stages. Both herbicides caused significant injury to wheat; however, wheat response to both herbicides was different. Glufosinate injury occurred rapidly and consisted of mainly leaf necrosis. Glyphosate injury to wheat was minimal and manifested in the form of leaf yellowing. Glyphosate caused shortened flag leaf when applied at PI and reduced canopy height when applied at boot. Injury was minimal to wheat across all treatments, with the highest level of injury being 34% following glufosinate applied at boot. Conversely, wheat was most sensitive to glyphosate at the 3- to 4-leaf stage. Flag leaf length was reduced the greatest by glyphosate at PI, whereas glufosinate reduced flag leaf length minimally. Even though glyphosate injury was lower than that of glufosinate, yield was reduced more by glyphosate. Wheat seed weight and germination were not affected by either herbicide. Wheat appears to be slightly more sensitive to glyphosate with respect to yield; however, it is slightly more sensitive to glufosinate with respect to foliar injury.  相似文献   

15.
Methods of harvesting seed of perennial ryegrass cv. S24 treated with the growth retardant paclobutrazol applied at spikelet initiation at a rate of 2.0 kg active ingredient ha−1 were examined in 1982. The greatest seed yield (2202 kg ha−1) was obtained from swathing the crop at 35% seed moisture content and combining 2 days later, but this was not significantly different from that obtained from swathing at 48% seed moisture content or double direct combining at 35% seed moisture content. Seed yields from a single direct combining at either 35% or 25% seed moisture content were significantly lower than those of other treatments.  相似文献   

16.
Eight lots of seed of S23 perennial ryegrass which had been artificially dried to different moisture levels and stored for 20 years were tested for germinating capacity, and the effects of long-term storage on subsequent plant development were studied. The results of the germination tests indicated a continuation of the downward trend in viability previously reported. Observations on the derived mature plants revealed no difference between lots in general growth habit; a few seedlings showed symptoms of some retardation in growth but most plants manifested the high tillering and prostrate growth typical of S23 perennial ryegrass. Pollen fertility was markedly reduced in 38% of all the plants sampled. The seed-setting capacity was affected to an even greater extent, 44% of the plants giving seed-set values decidedly below those obtained for plants grown from new seed. Where pollen fertility had been much reduced, seed-setting also was usually low, but there were some instances of satisfactory pollen fertility associated with a low seed set.  相似文献   

17.
At a site in Kent, perennial ryegrass (Lolium perenne) variety S24 and Italian ryegrass (L. multiflorum) variety RVP, wheat varieties Armada and Norman, and the original mixed grass ley were grown in small plots during 1982–84. Two toxic pesticides (phorate and aldicarb) were applied to half the total number of plots three times each year to eliminate soil invertebrate populations. Fertilizer was also applied to most plots. The yields of the crops, grown with and without pesticide, and the effects of the fertilizer were compared. Grass herbage yield was measured on three occasions during the summers of 1983 and 1984. Wheat grain yields were also determined in 1983. During the first year significant differences were not apparent in grass dry matter yield between pesticide-treated and non-treated plots, but significant differences were found in the second year. The perennial ryegrass was more susceptible to pest damage than the Italian ryegrass or the grass ley. Grass yields varied between cuts and in relation to variety and pesticide treatment, yields tending to be greater in untreated plots. Fertilizer treatment greatly increased grass dry matter yields, particularly with the Italian ryegrass. The effects of pesticide treatment on both wheat varieties varied although some yield enhancement was evident. Invertebrate animal populations in pesticide and fertilizer-treated plots were also assessed in autumn 1982, spring and autumn 1983 and spring 1984. In contrast to pesticide treatment, fertilizer treatment had little effect on soil invertebrate populations. Nematode populations were reduced at each sampling occasion by the pesticide treatment. Slug populations were initially unaffected but were subsequently reduced. Leatherjackets, by far the most abundant pest in both grass and wheat plots, were markedly affected by pesticides on all sampling occasions. Generally, fewer soil-dwelling dipterous larvae were recovered in spring than in autumn. Stem-boring dipterous larvae were virtually absent.  相似文献   

18.
Autumn defoliation of the early perennial ryegrass, S24, expedited or delayed heading and increased or decreased the number of heads and seed yield, according to the age of the stand, winter conditions and previous management.
Nitrogen applied as late as anthesls significantly increased the seed yield of the first harvest crop, but the after-effect on the next seed crop was not better than from an application made immediately after the first harvest. One application in spring was more effective than two in the previous summer and autumn.
Autumn defoliation influenced seed yield more strongly than the gross weight of the unthreshed crops.  相似文献   

19.
PEG-6000对不同黑麦草品种萌发期抗旱性的影响   总被引：1，自引：0，他引：1  
为了筛选适应湖南地区种植的优良黑麦草品种,采用0、5％、10％、15％、20％的聚乙二醇（PEG-6000）溶液模拟干旱胁迫条件,对13个不同类型黑麦草品种种子的相对发芽率、发芽势、发芽指数、种子活力指数、胚根／胚芽等进行了分析和综合评价。研究结果表明,沃土、特高、俄勒冈四倍体等黑麦草品种种子萌发期的抗旱性强;雅晴、潘多拉、抗锈王、首相、夜影Ⅱ、匹克、剑宝、麦迪和顶峰等黑麦草品种种子萌发期的抗旱性中等;冬绿的种子萌发期抗旱性最差。  相似文献   

20.
Preharvest application of 1 and 2 litres ha-1 IPA glyphosate (glyphosate) to a seed crop of S24 perennial ryegrass with moisture concentrations of around 400 and 340 g kg-1 (40 and 34% moisture content w/w) failed to significantly lower seed and straw moisture concentration at harvest and consequently did not affect combine rate. Addition of extra surfactants and ammonium sulphate to glyphosate did not significantly increase the rate of desiccation.
The quality of harvested seed was impaired at both rates and application times. Germination was significantly lowered through the production of abnormal seedlings. The germination of seed harvested in the previous year from glyphosatetreated plots decreased with storage. Seed vigour, germination rate and field emergence were also significantly decreased as a result of glyphosate application. The effect of glyphosate on seed quality precludes its preharvest use as a desiccant in the ryegrass seed crop.
Harvesting difficulties due to the production of secondary vegetative tillers may be overcome by swathing rather than direct combining.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号