Ryegrass Populations Research Articles

Optimum Cutting Stage of Forage Plants : VI. Seasonal changes of light diminution coefficient and seasonal productivity in Italian ryegrass population

Optimum Cutting Stage of Forage Plants : VI. Seasonal changes of light diminution coefficient and seasonal productivity in Italian ryegrass population

Genetic resources in high-rainfall hill pastures of New Zealand

Abstract Sixty-six ryegrass (chiefly Lolium perenne L.) populations colleeted from high-rainfall hill country were grown as spaeed plants for 3 years at Palmerston North for deseriptive analysis. All populations were highly variable and most were similar. They were mostly early heading, free seeding, but quite persistent. An unusually vigorous population came from old experimental plots in tussock grassland near Waiouru, and a very late-heading population from a terraee at Te Awa. Southland populations were ereet, small in diameter, and not very vigorous. Eastern districts of the North Island provided several unusually vigorous, leafy, erect populations, most of which came from unimproved farms with low available soil P. In general, populations from low-P sites grew better than those from high-P sites. Oversowing and topdressing did not appear to have altered the characteristics of the ryegrass populations and aspect had only a weak effect.

III. Variation in plant viruses: Variation in ryegrass mosaic virus in relation to resistance

ABSTRACTSome isolates of ryegrass mosaic virus are mild in all but a few plants, others are more severe. Infection with a severe isolate reduced the yield of a ryegrass population by 24% under field conditions and reduced survival following cold treatment by 85%. Field isolates from the short‐lived Italian ryegrasses are generally severe while those from the long‐lived late‐flowering perennial ryegrasses are generally mild. This variation appears to be adaptive in origin since in the case of perennial ryegrass proneness to infection by severe isolates would probably lead to the elimination of both host and virus whereas Italian ryegrass can escape infection readily by copious production of seed.

Optimum Cutting Stage of Forage Plants : III. Seasonal changes of LGR and average leaf area productivity in Italian ryegrass population

Optimum Cutting Stage of Forage Plants : III. Seasonal changes of LGR and average leaf area productivity in Italian ryegrass population

Optimum Cutting Stage of Forage Plants : IV. Seasonal changes in LAI and NAR with growth of Italian ryegrass population

Optimum Cutting Stage of Forage Plants : IV. Seasonal changes in LAI and NAR with growth of Italian ryegrass population

Survivor populations of S23 perennial ryegrass from zero‐grazed and set‐stocked swards

AbstractPerennial ryegrass tillers were collected from intensively used set‐stocked and zero‐grazed leys and from an old permanent pasture, grown on and compared at 30 cm spacing. All swards except the permanent pasture had been sown with cv. S23 and were of known age, ranging from 6 months to 11 years from sowing.Each genotype was scored for date of inflorescence emergence, and subsequently in vitro dry matter digestibility (DMD), D‐value of green leaf and the ratio of leaf dry weight: stem dry weight were determined.Both DMD and D‐value declined significantly in green leaf samples of populations from the older zero‐grazed swards but no significant changes were detected in populations from set‐stocked swards. In set‐stocked populations there was a shift towards later flowering.In zero‐grazed populations there was a consistent increase in the amount of leaf relative to stem with the age of the sward from which the plants were sampled. The survivor plants were more prostrate and leafier and it is suggested that under zero grazing, where cutting was to a uniform height, plants of this form were less severely defoliated and thus at a selective advantage.

Studies on the Effect of Sulphur Dioxide on Perennial Ryegrass (Lolium perenneL.)

The response to S02 fumigation was examined in long-established perennial ryegrass populations from the same climatic region, which had experienced widely different ambient S02 concentrations. The results provide strong evidence of the evolution of S02 tolerance in populations from the high S02 areas. Populations from these areas exhibited greater tolerance to S02 and showed reduced clonal variability in response. Furthermore, the degree of tolerance exhibited appeared to depend on the severity of S02 pollution experienced by the populations in the field. INTRODUCTION One example of the manner in which man's activities can cause evolutionary change in plant populations over relatively short periods of time is the evolution of tolerance to heavy metals in plants (Bradshaw, 1975). Differential responses to S02 fumigation dependent on the site of origin of plant populations have been shown by Bell and Clough (1973), Horsman and Wellburn (1977), and Taylor and Murdy (1975). Recent research has shown that S02 can markedly affect the growth of peren nial ryegrass (see discussion in previous paper). Hence in areas which have experi enced a long history of high ambient S02 concentrations, ryegrass populations may have evolved some degree of tolerance, providing that sufficient inherent genetic variability in response to S02 existed within the population. The findings of Bell and Clough (1973) strongly suggest that the indigenous ryegrass population at Helmshore (24 km north of Manchester) has evolved tolerance to S02. It was not known, however, to what extent the response of the two ryegrass clones selected from Helmshore reflected an overall population response. Since urban areas of Liverpool have experienced consistently higher S02 concentrations than Helmshore (Anon., 1972) any evolution of tolerance to S02 may be more evident in ryegrass populations from Liverpool than Helmshore. We have therefore investigated (a) overall population responses and (b) variability in 1 Present address: School of Botany, University of Melbourne, Australia. 2 Present address: Central Electricity Research Laboratory, Leatherhead, Surrey. This content downloaded from 207.46.13.73 on Thu, 11 Aug 2016 04:46:37 UTC All use subject to http://about.jstor.org/terms 496 Horsman, Roberts, and Bradshaw—Sulphur Dioxide Effects on Ryegrass genotype response to S02 in long established ryegrass populations from Helm shore, urban areas of Liverpool (high S02), and the Wirral peninsula (low S02 area, 10-20 km south-west of Liverpool). MATERIALS AND METHODS Clones of ryegrass were collected at random from the sites shown in Table 1. The populations from Newsham, Wavertree, West Kirby, and Birkenhead were collected from the lime lines of tennis courts (pH 5-5-6-5). This was necessary since, in Liverpool, these were the only areas of parkland where substantial perennial ryegrass populations survive due to the general acidification of the rest of the parkland, presumably as a result of the high S02 concentrations they have experienced. This means that although the populations have experienced widely different ambient S02 concentrations the climate, soil, and management conditions have been comparable. Table 1. Origin of ryegrass populations and typical winter mean S02 con centrations (jug m~3) found at these sites Site Late 1950s early 1960s Helmshore 100-140 80 Liverpool Newsham 600-700 200 Wavertree 600-700 200 West Kirby 60-80 35 Wirral Birkenhead 80 40 University 60-80 40 Botanic Gardens, Ness The ryegrass clones were individually identified, planted in a John Innes compost (pH 6-0), and grown in a greenhouse at the University Botanic Gardens, Ness, for at least 6 months. Experi mental design and procedures were as described in the previous paper.

Selection for resistance to ryegrass mosaic virus and crown rust (Puccinia coronata Corda) in Italian ryegrass populations

AbstractInoculation in the glasshouse revealed marked differences in resistance to both ryegrass mosaic virus (RMV) and crown rust (Puccinia coronata Corda) among eight unselected populations of Italian ryegrass (Lolium multiflorum Lam.). Two generations of selection for crown rust resistance led to a significant improvement in all eight populations, while one generation of selection for RMV gave a more variable response. Frequency distributions of individual genotype scores suggested that much of the resistance to crown rust was under the control of one or two genes with major effects, while resistance to RMV appeared to be controlled by a large number of genes each having a small effect.In the field, resistance to RMV meeisured after 20 months was strongly correlated with that obtained in the glasshouse. Natural infection by crown rust in the field was too low to reveal any differences between populations, although three populations from the Po Valley region of Northern Italy became heavily infected with Puccinia recondita.Selection for disease resistance significantly reduced the persistency of three populations, but that of four others was unaffected and one showed a significant improvement. Selection reduced water‐soluble carbohydrate (WSC) levels in spring slightly but significantly from 27.6 to 25.8% WSC overall. These results emphasize that agronomic performance must be monitored during selection for disease resistance.

Evolution of sulphur dioxide tolerance in perennial ryegrass

THE combustion of fossil fuels for domestic and industrial purposes, coupled with rapid industrial growth over the past 150 years, has resulted in sulphur dioxide becoming an integral part of the environment. Extensive research into the effects of sulphur dioxide on vegetation began in the 1920s, but the possibility of evolution of tolerance has only recently received attention, in spite of the implications of this for the overall effect of SO2 in the field. We present here data that provide strong evidence for the evolution of SO2 tolerance in a perennial ryegrass population from an urban area of Merseyside, UK.

Dalapon resistance in Lolium perenne populations

AbstractThe resistance often early, ten medium late and ten late flowering ryegrass populations to two rates of dalapon (2.8 and 5.6 kg ha‐1 acid equivalent) was measured in a box experiment. There was no difference in the mean effect of dalapon on the maturity groups at the time of greatest yield reduction, but the recovery of the late flowering population was, on average, better than that of the medium late group. There was a range of reaction to herbicide within all three maturity groups and, in general, the high yielding populations without dalapon were the most resistant, but there were exceptions. Assessment at 2.8 kg ha‐1 acid equivalent gave a similar ranking order to that using twice the amount of dalapon. The results of the current box experiment with seedlings were consistent with those obtained in the field at another location (Faulkner, 1974) for the eleven cultivars common to both trials. The resistance of a permanent pasture population was much lower than that of some cuttivars.

Frequency of Aneuploids in Autotetraploid Populations of Italian Ryegrass (Lolium multiflorum Lam.)

The frequencies of aneuploids and meiotic behaviours were studied in early and advanced generations of induced autotetraploid Italian ryegrass. The mean proportions of aneupl.oids were 59% in early generation and 47% in advanced generation, and the difference between them was significant. But, the populations selected by snow endurance, though those were in advanced generation, had aneuploids as frequently as those in early generation. A higher frequency of bivalents and lower frequency of quadrivalents were found in advanced generation than in early generation. It is estimated that the frequencies of aneuploids in each population of advanced generation have been already reached in equilibrium state, and, this equilibrium value is variable in relation to the fitnesses of aneuploids and euploids.

Optimum Cutting Stage of Forage Plants : II. Seasonal changes of CGR and average productivity in Italian ryegrass population

Optimum Cutting Stage of Forage Plants : II. Seasonal changes of CGR and average productivity in Italian ryegrass population

Nitrogen responses of tall fescue and ryegrass survivor populations from a rate-of-nitrogen experiment

Abstract Survivor populations of ryegrass and tall fescue from an experiment in which nitrogen was applied at rates of 0 to 1344 kg/ha/year were tested for nitrogen response in the range from 0 to 4352 kg N/ha in a single application. Applications above 544 kg N were supra-optimal and were totally toxic at 4352 kg N. There were no indications of adaptation of the different survivor populations to either sub-optimal or supra-optimal levels of nitrogen.

Optimum Cutting Stage of Forage Plants : I. Fitness of logistic equation to the growth of Italian ryegrass population

Optimum Cutting Stage of Forage Plants : I. Fitness of logistic equation to the growth of Italian ryegrass population

Studies on Variation and Selection in Italian Ryegrass Populations. I. Variation of Fresh Weight and Dry Matter Weight

Investigation of variation among variety groups indicated that Japanese local varieties produce higher dry matter from autumn to early spring than foreign varieties, and within-variety variation and selection suggested high potential variation in Japanese local varieties.

Studies on Variation and Selection in Italian Ryegrass Populations. : III. Response to Selection for Higher Dry Matter Weight

Within-population selection was carried out for three generations, and Japanese Italian ryegrass populations increased dry matter weight but no plateau in selection was reached. Degree of inbreeding depression in small populations and heterosis in a synthetic population were investigated. Possibility of further improvement in the growth from autumn to early spring in Italian ryegrass was discussed.

Studies on Variation and Selection in Italian Ryegrass Populations. : II. Variation of Heading

Japanese local varieties are early in heading, and response to environmental change and selection indicated existence of high potential variation of heading in the local variety.

Pasture management and cultural methods for the control of annual ryegrass (Lolium rigidum) in wheat

The effects of four pasture management treatments-haycutting, heavy grazing, burning and a control-and two cultural treatments,-mouldboard or disc ploughing-on the densities of annual ryegrass (Lolium rigidum) under subsequent wheat crops, was measured in 16 experiments conducted from 1961 to 1968. Pasture management treatments before cropping significantly reduced subsequent ryegrass populations in first, second, third and fourth year crops, compared with the untreated control and increased grain yields in the first and second year crops. Subsequent ryegrass populations were reduced more by mouldboard ploughing than by disc ploughing and this was reflected in higher yield for all crops. The results indicate that these management and cultural methods may obviate the need for chemical control in first and second year crops.

INFLUENCIA DE LOS SISTEMAS DE CORTES EN LA PRODUCCION DE FORRAJE DE TREBOL ROSADO, SEMBRADO SOLO Y EN MEZCLA CON BALLICA DE ROTACION CORTA

During 1971-1973 experiments were conducted at the Carillanca Experimental Station (Cautin Province, Chile) to determine the yield potencial of red clover (Trifolium pratense L.) cultivar Quinequeli under different cutting systems when it was seeded alone or in mixtures with short rotation ryegrass, (Lolium perenne L. x L. multiflorum Lam), cultivar Manawa. The cutting systems were: 1) Cut when plants reached 25 cm heigth, 2) at the tillering stage; 3) when 50% plants were in bloom stage and 4) during the third week of november, january and march. During the first season (1971-72) no differences were observed between the production of red clover and the mixture. The rye-grass and red clover mixture gave the highest dry matter yield per hectare in the second season of utilization (1972-73). The main component of the mixture being rye-grass. The highest yield per hectare was produced in the 50% blooming stage and only one cutting was obtained during the season. In the mixture, no differences were found among the tillage stage cuttings, third week of November, January and March and the 50 percent-blooming stage. The total yield was lower when the cutting at 25 cm was compared with the 50 percent-blooming stage cutting. The vegetative stages of rye-grass and those corresponding to red clover were not coincident with the 50 percent-blooming stage cutting. The red clover population declined continuously jn all treatments and performed independent of the different cutting systems, possibly due to disease or insect damage, throughout the two period of growth under control. The rye-grass population was also constant in density of plants per unit of area. These results were analysed refering to the pasture of the Cautin Province, Chile.

Selective chemical control of annual ryegrass (Lolium rigidum) in oilseed rape, field peas and lupins

The effectiveness of herbicides for selective control of annual ryegrass (Lolium rigidum) in oilseed rape (Brassica napus), field peas (Pisum arvense) and narrow-leafed lupins (Lupinus angustifolius) was investigated in nine experiments in north-eastern and southern Victoria. Of the herbicides tested, di-allate, trifluralin and simazine significantly reduced ryegrass populations in all experiments where they were used. Pre-planting incorporated treatments were generally more effective than post-sowing or post-emergence treatments in oilseed rape and field peas. Control of ryegrass generally resulted in higher grain yields in all three crops, although lupins showed the greatest response. Dalapon, applied to oilseed rape after emergence, caused flower distortion and reduced yields in some experiments.