Winter hardiness in Lolium multiflorum Lam. I. The effect of nitrogen fertilizer and autumn cutting managements in the field

Four Italian ryegrass varieties of different origins and winter hardiness were grown as spaced plants at a lowland and an upland site and subjected to ten managements comprising two nitrogen levels and five autumn cutting treatments. Tiller mortality after the winter of 1971–72 was measured in March and subsequent spring recovery from winter damage in April. Although the winter was not severe, there was considerable winter kill, particularly at the upland site where the most severe treatment combinations killed up to 90% of the plants of the more susceptible varieties. In general, winter kill was increased by raising the level of nitrogen fertilizer and by late or frequent autumn defoliations, and significant interactions between locations and the two treatment factors emphasized the importance of the siting of the experiment. The varieties difFered in their overall winter hardiness, with Bb 1430 and RvP suffering less tiller mortality than S22 and Grasslands Paroa in all the treatment combinations, but significant interactions of varieties with locations and cutting treatments revealed that the magnitude of the difference between varieties varied with location and cutting management. Regression analysis of these interactions, however, showed that the tiller mortality of all four varieties increased linearly with the increasing stresses applied by the location × management combinations. There was no differential variety recovery from winter kill, the spring yields being entirely related to the level of tiller mortality experienced. These results are discussed in relation to the breeding of winter hardy varieties, the choice of variety and autumn management practice.     

The relationships between stolon characteristics, winter survival and annual yields in white clover (Trifolium repens L.)

Five white clover populations of Swiss origin and three bred varieties were grown in binary mixtures with two perennial ryegrass varieties, Aurora and S23. The seasonal yields of clover and grass plus clover were measured under a cutting regime during the second and third years after establishment. A series of destructive detailed sward measurements was made during the late autumn to spring period preceding each harvest year. In this way changes in the amounts of stolon, leaf plus petiole and numbers of growing points were monitored during the winter.
There were large differences in clover yield between populations in both years. These were evident from the first (spring) harvest in each year. Higher-yielding clovers in spring tended to produce higher annual clover yields. No grass × clover interaction was evident at any harvest. Large differences between clovers were also apparent in the morphological characteristics measured, with the Swiss material generally having greater amounts of stolon, leaf plus petiole and numbers of growing points present in early spring. It is proposed that these factors contribute to the high spring yield in the Swiss populations. Loss of stolon length over each winter was less in the Swiss material, indicating that its good spring growth was not obtained at the expense of winter hardiness. Annual clover yield was found to be significantly positively correlated with the amount of stolon present in spring, exemplifying the importance of stolon survival over the winter.     

THE AGRONOMIC EVALUATION OF SYN 1 TALL FESCUE IN THE WEST OF SCOTLAND

The agronomic value of Syn 1 tall fescue, a synthetic variety derived from North African parent material, was determined in three experiments. Herbage yield, sward purity and digestibility were measured under cutting treatments for incremental sward growth during autumn/winter, and for sward regrowths during autumn/winter, spring and a complete season. Similar data were obtained for sward regrowths during autumn/winter and spring under defoliation by grazing. Syn 1 was compared with several of the north-temperate region tall fescues, e.g. S170, Rozelle and Manade, also with S143 cocksfoot Syn 1 showed yield superiority in autumn/early winter when there were comparable populations of tall fescue. Under cutting management, Syn 1 swards thinned out rapidly because of lack of winter-hardiness and yields were depressed in the second season; the effects were worst under the winter foggage-type management. Under grazing, with probably less severe defoliation, Syn 1 swards maintained yields for an additional season, but thereafter failed to persist Syn 1 swards had low spring- and annual-yields. The yield advantage of Syn 1 in autumn/early winter was not sufficient to be of great agricultural value and with its shortcomings in winter-hardiness and annual yield, it was considered unsuitable for West of Scotiand conditions. The main value of plant material such as Syn 1 may lie in ccmferring autumn/winter growth potential to winter-hardy north-temperate tall fescues in a breeding programme.     

The winter hardiness of Festuca rubra, Holcus lanatus and Agrostis spp. in comparison with Lolium perenne

Preliminary experiments were conducted to assess the winter hardiness of representative cultivars or populations of Festuca rubra, Holcus lanatus and Agrostis spp. in comparison with a hardy (Premo) and a susceptible (Grasslands Ruanui) cultivar of Lolium perenne. Two controlled-environment tests and a field experiment including two cutting and two fertilizer managements are reported.
Grasslands Ruanui and H lanatus suffered most damage in all tests. In the controlled-environment experiments, Premo was at least as hardy as the F. rubra and Agrostis cultivars but in the field Premo was more susceptible. Spring growth of Premo was affected more by the cutting and fertilizer managements applied the previous summer and autumn than was spring growth of F. rubra or Agrostis spp.
It was concluded that, whereas use off. F. rubra or Agrostis spp. should not be limited by fears of winter damage, poor winter hardiness may limit the value of H. lanatus for hill and upland reseeding.     

THE EFFECT OF DEFOLIATION ON THE SEED-PRODUCING CAPACITY OF BRED VARIETIES OF GRASSES

Leafy grass varieties S24 perennial ryegrass, S26 cocksfoot, S215 meadow fescue and S51 timothy were cut in October and at various growth stages in spring; S53 meadow fescue was grazed at similar periods. Sub-plots were given different applications of N. The control plots had similar manurial treatments but were not defoliated. The seed yield of S24 following October cutting was significantly lower than the control in the first harvest year and significantly higher in the second; the mean yields over 2 years, as a result of cutting at this stage and before ear formation in March, were very similar to those of the control treatment. The mean yields from 3 harvest years for S26, S215 and S51 were generally improved by cutting in October and before ear formation, but cutting after ear formation reduced the number of heads and the seed yields. Extra N applied in conjunction with the defoliation had no significant effect on the number of seed heads or on seed yield. Double grazing of S53 in Sept. and Dec. reduced significantly its seed production in both harvest years. Application of N in spring gave a greater response than a similar application in autumn.     

THE EFFECT OF CUTTING TIMOTHY (PHLEUM PRATENSE L.) GROWN FOR PRODUCTION OF SEED

An experiment is described in which timothy, grown for production of seed, was cut once annually on dates ranging from 23 October to 24 May. New tillers in selected plants were labelled at monthly intervals during autumn and winter for 2 years, to determine the pattern of production of tillers and to assess the reproductive development of categories of tillers. The majority of tillers were produced in autumn, but production was continuous throughout the winter. There was a big increase from the first to the second year in the total number of tillers produced, but neither the pattern nor amount of tiller production was affected by cutting. The % of fertile tillers was highest in the oldest tillers, and was affected little by the increase in the number of tillers from the first to the second year; cutting had little effect on the % fertility except where floral primordia were removed by the cut on 24 May. In all treatments at least 90% of the ears at harvest were produced by tillers initiated the previous autumn. The penetration of light to the base of the plants was increased considerably by cutting, but it is concluded that interception of light by the whole plant is more beneficial than an increase in the penetration of light into the plant and a concomitant reduction in the total interception of light by the plant.     

Winter hardiness in Lolium multiflorum Lam. II. The effect of defoliation and nitrogen application as assessed by low temperature response in a controlled environment

The effect of defoliation and nitrogen application on the cold tolerance of four varieties of Italian ryegrass was assessed using controlled environment chambers. Both defoliation and nitrogen fertilizer markedly reduced overall cold tolerance and this closely matched changes in winter hardiness induced by similar treatments applied to the same varieties in a field experiment. However, the relative response of individual varieties differed from that found under field conditions. Thus, RvP showed high levels of tolerance to low temperatures in the controlled environments and was also winter-hardy under field tests; by contrast Bb 1430, although previously shown to be winter hardy in the field, exhibited low tolerance of cold stress in growth chambers. Thus, results obtained in controlled environment tests cannot be entirely equated to winter hardiness in the field. Water-soluble carbohydrate (WSC) levels were reduced by both defoliation and nitrogen application and there were significant overall differences between varieties. It was not possible, however, to detect any clear relationship between these differences in WSC levels and cold tolerance. The significance of these results in relation to the use of controlled environment chambers for selecting for improved winter hardiness is discussed.     

THE EFFECT OF NITROGEN APPLICATION AND AUTUMN MANAGEMENT ON AUTUMN GROWTH, WINTER 'BURN' AND SPRING GROWTH OF LOLIUM PERENNE L. AT ABERYSTWYTH, EDINBURGH AND CAMBRIDGE.

A trial was carried out to find management practices which would permit the best discrimination for winter performance of erennial ryegrass cultivars. Due to the mild winter experienced only a few of the plants were killed outright. The cultivars were therefore assessed for percentage of green herbage and for spring growth. There were four sites: an upland and lowland site at Aberystwyth and one site each at Edinburgh and Cambridge. At all sites two N rates (totals of 125 or 550 kg/ha in the first year after sowing) and 5 autumn cutting treatments were used to give differences in the amounts of herbage remaining at the onset of winter. The last dates of defoliation in the autumn were: C₁ end of August; C₂ end of September; C₃ end of October; C₄ mid-November; C₅ was cut on all these dates. Four cultivars (Grasslands Ruanui, S321, Premo and Argo) which differed in their autumn growth potential, frost susceptibility and degree of winter dormancy were grown. The autumn yield of S321 was, in general, higher than that of the other cultivars but there were interactions with N, management and location. The data on percentage of herbage remaining green in February illustrated differences due to the siting of the trial. In the conditions prevailing the two Aberystwyth sites facilitated greater discrimination between cultivars than those at Edinburgh and Cambridge. In three of the four sites the management which produced most winter ‘burn’(including both that due to natural senescence and that due to winter damage) involved accumulation of herbage in the autumn but there were considerable sites × managements interactions. For example at Cambridge management produced no significant effect whereas at the Aberystwyth lowland site frequent defoliation in the autumn had more effect than allowing herbage to remain uncut after the end of August. High N significantly decreased the percentage of green herbage only at the two Aberystwyth sites. Over five-fold differences in spring yield were obtained, the heaviest yields being recorded at Edinburgh and Cambridge. However, there were large interactions between environments and cultivars; for example the higher N rate reduced spring yield at Aberystwyth but increased spring yield at Edinburgh and Cambridge. Premo and S321 had similar yields in spring at the Aberystwyth lowland and Cambridge sites but Premo was higher yielding than S321 at the Aberystwyth upland site and at Edinburgh. The large environmental effects and their interactions with cultivars illustrate the difficulties of cultivar assessment and the dangers inherent in national recommendations for grass cultivars.     

THE GROWTH OF VARIETIES OF PERENNIAL RYEGRASS IN THE SEEDING YEAR

These studies showed that in the first autumn the capacity for soil establishment of different varieties of perennial ryegrass was connected with seed size. On one of two experimental fields, shoot production in the early stages was found to be positively correlated with seed size. The rate of tillering was initially similar for all varieties, but by January or February, the pasture varieties had the highest tiller numbers. However, shoot weights at this time differed very little from variety to variety. Tillering virtually ceased during December and January and started again in February.
The yields obtained from the five varieties in spring, when cut with an autoscythe. differed greatly despite the similar shoot weights of individual plants. It is suggested that the spring growth in pasture varieties is largely below cutting level.     

九个黄淮和长江中下游冬麦区的优质冬小麦品种在晋中麦区的生育及品质表现

为拓宽山西优质小麦品种资源,采用田间试验,分秋播(2010年9月28日)和春播(2011年2月28日)两个播种时期,研究了来自黄淮冬麦区和长江中下游冬麦区的9个优质小麦品种在晋中晚熟冬麦区的农艺、产量及品质性状表现。其中黄淮冬麦区品种为烟农19(冬性,强筋)、淮麦18(半冬性,中筋)和宁麦9号(冬性,弱筋),长江中下游冬麦区品种为镇麦168(春性,强筋)、皖麦33(春性,强筋)、宁麦13(春性,弱筋)、扬辐麦2号(春性,弱筋)、扬辐麦4号(春性,弱筋)和扬麦15(春性,弱筋)。结果表明,烟农19和淮麦18在晋中麦区秋播可正常越冬,并获得相当的产量,且烟农19的成穗数和产量高于淮麦18;9个引进小麦品种在晋中麦区春播均可抽穗成熟,但因2010-2011年度秋冬春三季连旱,所有品种在苗期到拔节期受旱,因而均未能获得较高的籽粒产量。烟农19和淮麦18的籽粒产量和品质秋播明显高于或优于春播。总体来看,在晋中麦区,烟农19和淮麦18适宜通过秋播种植加以利用,扬辐麦2号、宁麦9号有望通过春播种植加以利用。     

THE PRODUCTION OF WINTER GRASS FROM A ROW CROP OF COCKSFOOT AND LUCERNE

A crop of cocksfoot and lucerne in alternate rows was subjected to various autumn treatments for winter pasture. The yield of grass in winter, and the effect of autumn and winter treatments upon yield and composition in the following spring, are reported and discussed.
Maximum yield of winter grass was achieved by resting from an early date and applying nitrogenous fertilizer. The response to fertilizer applied in August and mid-September for winter grass production was as good as that obtained on ordinary swards at other times of the year. To ensure an adequate yield in any year the crop would need to be rested from early August and to receive about 70 lb N per acre.
The spring growth of cocksfoot was distinctly retarded by cutting twice in winter, i.e. in November and February. Cutting once only had no such adverse effect.
Both cocksfoot and lucerne persisted satisfactorily. The use of nitrogenous fertilizer to promote autumn growth of grass did not greatly reduce the overall productivity of the lucerne.
The two species were complementary in the sense that, in combination, they maintained a high aggregate yield of herbage under a range of weather conditions in midsummer and in winter.     

Minimizing environmental impacts of grassland weed management: can Cirsium arvense be controlled without herbicides?

Invasion by undesirable plants, such as Cirsium arvense, can constrain attempts to conserve and restore biodiversity in extensively managed temperate grasslands, but control with herbicides can cause environmental harm. We contrasted herbicides with more environmentally sustainable weed control strategies. Six‐year, large‐scale randomized block experiments were established to determine optimum combinations of grazing management and mechanical or herbicide treatments to control thistles within lowland and upland grazing systems. Factorial combinations of tight vs. lenient grazing in spring and autumn with additional treatments of winter grazing were compared. Thistle control methods were applied in sub‐treatments for the first 2 years: cutting twice yearly, herbicide wiping, and cutting followed by herbicide application. Thistle abundance decreased under lenient grazing in spring, autumn and winter at the lowland site, under lenient spring and winter grazing in the uplands and under cattle compared with sheep grazing. Herbicide wiping was the most effective control measure and cutting the least, but effects of all weed control sub‐treatments were lost rapidly, so lenient grazing was sufficient to give long‐term thistle control. Lenient grazing and herbicide wiping also caused small declines in non‐target forb diversity. Control of creeping thistle can therefore be achieved without herbicides because lenient grazing in spring and autumn can decrease thistle populations to sufficiently low levels. Severe infestations can be more rapidly controlled using herbicides, but are better avoided at botanically diverse sites. Ecologically‐based weed control strategies have great potential, but require well designed field experiments, which run for sufficiently long periods to allow community‐level impacts to develop.     

The selection of winter wheat varieties for whole-crop cereal conservation

Ten commercial varieties of winter wheat were sampled at different stages of growth, and dry mailer (DM) yields and potential nutritional quality, as determined by modified acid detergent fibre concentration (MADF), were measured. Maximum yields for the different varieties were spread over a four-week period, when the DM content was above 350 g kg⁻¹. When the varieties were harvested for conservation as either fermented (DM 380 g kg⁻¹) or alkaline (DM 580 g kg⁻¹) whole crop, the mean MADF concentration was similar at both harvests, with large differences recorded between varieties. At both harvests the quality of the crops was sharply increased by raising the cutting height from 10 to 40 cm above ground level.     

The conservation management of mesotrophic (meadow) grassland in Northern England. 2. Effects of grazing, cutting date, fertilizer and seed application on the vegetation of an agriculturally improved sward

The plant species number and composition, iind yield of herbage biomass of an agriculturally improved hay meadow were assessed after 4 years under various combinations of grazing, fertilizer applicution. cutting date and seed addition treatments in a replicated split-plot design. Grazing treatments consisted of either autumn grazing with cattle and sheep, spring grazing with sheep or both regimes. Fertilizer application treatments consisted of either 25 kg ha^?1 N plus 12–5 kg ha^?1 P and K or no fertilizer. Cutting date treatments consisted of cuts on either 14 June, 2i July or 1 September. Seed addition treatments consisted of either no addition or sowing with a range of meadow species in the autumn. Data analysis was by correspondence analysis and analysis of variance. Species number decreased with fenilizer use and when the cutting date was 1 September. A range of species was affected by the main treatments and there were some first-order interactions, mainly between cutting date and fertilizer application. Rhinanthus minor was particularly favoured by the seed addition treatment. Species attnbutes in the regenerative and established phase were related to treatments and their effect on species composition. The National Vegetation Classification communities were associated with particular treatment regimes. The 21 July cutting date favoured ‘improved’ over ‘unimproved-traditional’ swards, with spring grazing favouring ‘unimproved-traditional’ swards. Lowest yields of herbage biomass were associated with autumn and spring grazing, the 14 June cutting date and no fenilizer treatments. The fenil-izer, 1 September cutting date and auiumn grazing treatments gave the highest yields. The implications of these results are discussed in terms of the conservation management required to return agriculturally improved mesotrophic grassland to a species composition similarto that of traditionally managed grassland.     

STUDIES ON THE EXTENSION OF THE GRAZING SEASON

In a small plot trial good yields of foggage of satisfactory botanical composition with cocksfoot dominant were produced from a mixed-species pasture after it had been cut for silage in spring and again in summer. Production in the following year was satisfactory. The advantages of using ordinary pastures for winter grazing, especially if this occurs only during their last winter before ploughing, are discussed. From a study of various autumn treatments it is concluded that the optimum management for foggage production in the north-east of Scotland is to close fields on or near 10 August when 3 cwt. nitro-chalk per ac. should be applied; a higher rate (6 cwt. per ac), though it increased yields and percentage crude protein immediately, and also during the subsequent summer, conferred no benefits of practical importance. Effects of K fertilizer applications were negligible. Closing as late as the beginning of September gave smaller but useful yields of a higher protein foggage and the sward was less cocksfoot-dominant. Autumn closing and fertilizer treatments did not affect foggage wastage during winter, which averaged 14 per cent of the initial organic-matter yield; the percentage of crude protein in standing foggage rose.     

THE EFFECT OF CUTTING COCKSFOOT (DACTYLIS GLOMERATA L.) GROWN FOR PRODUCTION OF SEED

An experiment is described in which cocksfoot, grown for production of seed, was cut annually for 3 years in either autumn, winter or spring. No significant increases in yield of seed/ac were obtained from any treatment compared with an uncut control, and a cut in late April in one year seriously reduced the yield of seed. Additional N applied after a defoliation in October did not increase the yield of seed compared with that from plots which were cut at the same time but not fertilized. The production of tillers was not affected by cutting on any date. The percentage fertility of tillers was increased by cutting in the first year, when the number of tillers was smallest; the fertility was less consistently affected in the second year, and was generally unaffected in the third year. The weight of seed produced per ear was usually reduced by the cutting treatments. In the third year of the experiment it was shown that the penetration of light to the base of the shoots was increased substantially by defoliation, but it is deduced that maximum interception of light by the whole plant is more important for the production of seed than increasing by cutting that proportion which penetrates to the base of the plant.     

VARIATION IN YIELD, MATURITY TYPE, WINTER GREENNESS AND SENSITIVITY TO CUTTING OF HILL GRASS SPECIES

Two experiments are described in which data were collected on yield, floral characteristics and winter greenness of a number of indigenous hill grass species. Differential cutting treatments, besides affecting total yield, affected yield and floral vigour in the subsequent year. Differences in sensitivity to cutting were present among the species. The date at which the grasses were last cut in autumn affected their winter greenness though responses differed among species. The significance of these results in relation to performance and management of hill pastures is discussed.     

The effect of cutting and grazing managements on dry matter yield of white clover varieties (Trifolium repens) when grown with S23 perennial ryegrass

The effects of three defoliation treatments upon the performance of eight white clover varieties when grown with S23 perennial ryegrass were investigated. These treatments included a cutting only regime as used in National List trials and rotational and continuous sheep grazing.
There were significant ( P <0·001) differences between treatments, and the ranking of clover varieties also differed between the three treatments. The significance of this finding is discussed in relation to the evaluation of breeding material and varieties prior to recommendation to farmers.
Clover yields were less under grazing than cutting. This was due mainly to the selective grazing and removal of stolon material which occurred in the former treatments. Differences in the grass/clover balance resulting from the three treatments are discussed in relation to the degree of protection afforded to the clover stolons by the grass component.     

大豆“短青春期”品种的光（温）反应研究：Ⅱ．对短日照的反应

在分析“短青春期”品种对播季反应的基础上，通过比较不同品种出苗至开花数与开花至成熟天数对短日处理的反应，以进一步明确夏大豆型“短青春期”品种的光（温）敏感性特征。研究结果表明：春播条件下，开花前短光照处理，“短青春期”品种中豆24和巨丰出苗至开花天数仅缩短2－14d，敏感度较小，与春大豆型品种相似，而与典型夏大豆品种，秋大豆品种和“长青春期”品种明显不同，中豆24和巨丰的出苗至开花天数对短光照不敏感。同为“短青春期”品种的中豆24和巨丰，其开花至成熟天数对短日处理的反应有明显差异，并者与春大豆相似，而后者的开花至成熟天数的短日照敏感不仅大于复大豆，而且也大于秋大豆。生育前期对短日照不敏感的品种，其短日处理效应在生育后期表现更加明显。本文还讨论了不同品种短日处理后效应的传递特征。     

抚育施肥措施对毛竹林笋产量的影响及效益分析

在毛竹林5个区组内分别采取劈杂（X2）、劈杂＋施肥（X3）、劈杂＋深翻＋施肥（X4）和对照（X1）4种处理措施,翌年测定各处理小区春笋产量并进行经济效益分析。结果表明,竹笋产量在各处理间有极显著差异,在各区组间差异不显著。4种处理措施中,X4、X3与X1、X2之间竹笋产量差异极显著,X4与X3之间差异显著、X1与X2之间差异不显著,表明劈杂对竹笋产量影响有限,施肥和深翻均能显著促进竹笋增产。经济收益以X4为最大,每公顷可增加收益3475．5元,明显高于X3和X2,说明抚育施肥可以取得显著的经济效益。