SELECTION FOR DRY MATTER YIELD IN LOLIUM PERENNE L. II. CORRELATED RESPONSES UNDER TWO CUTTING REGIMES

1980 ◽  
Vol 60 (2) ◽  
pp. 501-508 ◽  
Author(s):  
S. CECCARELLI ◽  
M. FALCINELLI ◽  
F. DAMIANI
Keyword(s):  
Lolium Perenne ◽  
Dry Matter ◽  
Leaf Size ◽  
Dry Matter Yield ◽  
Correlated Responses ◽  
Lolium Perenne L ◽  
Selection For ◽  
Cutting Regimes ◽  
Leaf Appearance ◽  
Rate Of Leaf Appearance

The correlated responses to divergent selection for dry matter yield within an ecotype of Lolium perenne L. were evaluated in two experiments under different cutting regimes. Both experiments showed that selection for dry matter yield did not affect leaf size and caused asymmetrical correlated responses on the rate of tiller production and the rate of leaf appearance. Selection for high dry matter yield resulted in an increased rate of tiller production without change in the rate of leaf appearance. Selection for low dry matter yield did reduce both the rate of leaf appearance and the rate of tiller production.

SELECTION FOR DRY MATTER YIELD IN LOLIUM PERENNE L. I. DIRECT RESPONSE TO SELECTION

1980 ◽  
Vol 60 (2) ◽  
pp. 491-500 ◽  
Author(s):  
S. CECCARELLI ◽  
M. FALCINELLI ◽  
F. DAMIANI
Keyword(s):  
Lolium Perenne ◽  
Dry Matter ◽  
Heritability Estimate ◽  
Forage Yield ◽  
Dry Matter Yield ◽  
Realized Heritability ◽  
Lolium Perenne L ◽  
Selection For ◽  
The Difference ◽  
Efficient Selection

Selection for high and low dry matter yield within an ecotype of Lolium perenne L. was effective in producing two highly differentiated populations. The evaluation of the materials obtained after three cycles of selection snowed a realized heritability of 0.13 and a symmetrical response in the two directions of selection. The difference between populations selected in opposite directions was 448.9 mg/plant and was significant from early stages of development. After four cycles of selection, realized heritability was 0.10. The low heritability estimate suggested that more efficient selection criteria for the improvement of forage yield are needed.

scholarly journals Developmental genetics of leaf formation in Lolium: 1. Basic Patterns of Leaf Development in L. Multiflorum and L. Perenne

1967 ◽  
Vol 9 (2) ◽  
pp. 233-245 ◽  
Author(s):  
K. J. R. Edwards
Keyword(s):  
Lolium Multiflorum ◽  
Leaf Size ◽  
Repeated Measurements ◽  
Developmental Genetics ◽  
Initial Growth ◽  
Leaf Elongation ◽  
Leaf Formation ◽  
Selection For ◽  
Leaf Appearance ◽  
Rate Of Leaf Appearance

1. Repeated measurements on the growth of individual leaves in seedlings and young plants of ryegrass combined with dissections of the apex of the shoot and of very young leaves have shown that the basic pattern of leaf formation is very similar in Lolium multiflorum and L. perenne.2. The initial growth rate of a leaf primordium is low but increases suddenly at a point when the primordium is somewhat longer than the apex and about 1 mm. in length. After this transition, which I have called the unfolding of the leaf, the rate of elongation is faster and more or less linear until the leaf is nearly mature.3. The time of unfolding of a leaf is very closely associated with the time of maturity of the next older leaf on the same side of the apex. Thus a leaf ceases growth when the next younger leaf immediately above it starts elongating rapidly, though which is cause and which is effect is it not possible to say.4. This close relationship between duration of leaf elongation and rate of unfolding of successive leaves holds for both species in two seasons. It leads one to predict that selection for increased leaf size, in so far as it is a result of greater duration of leaf elongation, is likely to be accompanied by a slower rate of leaf appearance, and conversely that selection for rate of leaf appearance is likely to result in smaller leaves.

Responses to selection for seed weight and seedling vigour in Phalaris

1974 ◽  
Vol 25 (1) ◽  
pp. 33 ◽  
Author(s):  
RJ Clements ◽  
BDH Latter
Keyword(s):  
Seed Weight ◽  
Leaf Size ◽  
High Rate ◽  
Hybrid Population ◽  
Direct Selection ◽  
Seedling Vigour ◽  
Developing Seed ◽  
Selection For ◽  
Leaf Appearance ◽  
Rate Of Leaf Appearance

Significant responses were obtained to three cycles of directional selection for seed weight, seedling weight, leaf size, and rate of leaf appearance in a broadly based P. tuberosa population. The responses were linear in both the high and low directions, and the realized heritabilities of the characters were 0.35, 0.12, 0.61, and 0.38 respectively. Leaf size was positively correlated with seedling weight and negatively correlated with rate of leaf appearance. Selection for high seed weight resulted in marked correlated increases in seedling weight and leaf size, but selection for heavy seedlings or large leaves did not significantly increase seed weight. Selection for light seedling or small leaves, on the other hand, led to a correlated decrease in seed weight. A hybrid population obtained by crossing the parents of the high leaf size line with those of the high rate of leaf appearance line had seedlings nearly as heavy as those of the high seedling weight line and significantly heavier than the mean of the two parent lines. This effect, together with other evidence of the effect of inbreeding on all characters, indicated some degree of directional dominance, particularly for leaf size. Plants in the high seed weight line matured earlier and had fewer heads. However, because they had heavier seeds and more seeds per head, there was no apparent decrease in seed yield per plant in this line, compared with the control population. Areas of the spikelets and leaf sheaths were greater in the high seed weight line, but areas of the flag and penultimate leaves were unchanged, and there was no evidence that increases in seed weight were accompanied by increases in the amount of photosynthetic area available to each developing seed. It was concluded that selection for large leaves is a relatively efficient means of increasing seedling weight, but results in a reduced rate of leaf appearance and possibly a slower rate of tillering. Selection for seed weight, though inefficient, exploits a source of variation largely untapped by direct selection for seedling weight.

scholarly journals Developmental genetics of leaf formation in Lolium: 2. Analysis Of Selection Lines

1967 ◽  
Vol 9 (2) ◽  
pp. 247-257 ◽  
Author(s):  
K. J. R. Edwards
Keyword(s):  
Leaf Growth ◽  
Selection Criterion ◽  
Leaf Size ◽  
Italian Ryegrass ◽  
Correlated Response ◽  
Response To Selection ◽  
Leaf Formation ◽  
Selection For ◽  
Leaf Appearance ◽  
Rate Of Leaf Appearance

Detailed measurements of leaf growth and leaf dimensions in the seedling stage were made on lines which had been selected either for large or small leaf size or for fast or slow rates of leaf appearance within one population of Lolium multiflorum (Italian ryegrass) and two populations of L. perenne (Irish perennial and Hunsballe perennial ryegrass).Selection for either character had no effect on the rate of initiation of primordia at the apex, but did change the rate at which successive primordia became leaves. This rate of unfolding was very highly correlated with the rate of visible appearance of leaves and in all cases showed a parallel response to selection for the latter, as did also the rate of maturation of leaves. All three rates showed a negative correlated response to selection for leaf size.Selection for increased leaf size in all cases led to a longer duration of the elongation of an individual leaf, but selection for faster rate of leaf appearance always reduced this duration. The rate of elongation of individual leaves increased under selection for larger leaf size but showed irregular changes under selection for faster leaf appearance, going down in Irish but up in Hunsballe.Data for dimensions of cells from the lower epidermis showed that changes in leaf length under selection were sometimes associated with changes in cell length, some-times in cell number and sometimes with both.Selection had in no case disrupted the close association between the maturation and cessation of growth of a leaf on the one hand, and, on the other, the unfolding from the apex and onset of rapid growth of the next younger leaf on the same side of the apex. Thus in all lines only two leaves (one on each side of the apex) were elongating rapidly at any one time, and an increase in the rate of unfolding was associated with a decrease in the duration of elongation and vice versa.This association was the basis of the observed negative correlated responses between leaf size and rate of leaf appearance. But the fact that the rate of elongation could change independently of the duration opened up the possibility of setting up a selection criterion which would increase the total rate of leaf area formation.The value of this kind of analysis of a character complex in a plant-breeding programme is suggested to lie in discovering physiologically or developmentally limiting processes rather than merely identifying morphological components.

Studies on the agronomy, genetics and interrelationships of yield and its morphological components in a diallel set of families of Lolium perenne L.

1973 ◽  
Vol 80 (3) ◽  
pp. 511-520 ◽  
Author(s):  
A. J. Thomson ◽  
A. J. Wright ◽  
H. H. Rogers
Keyword(s):  
Lolium Perenne ◽  
Dry Matter ◽  
Dry Weight ◽  
Dry Matter Yield ◽  
Lolium Perenne L ◽  
Large Numbers ◽  
Path Analyses ◽  
Main Effect ◽  
Breeding Programmes ◽  
Applied Nitrogen

SummaryFive selected clones of Lolium perenne were selfed and diallel crossed without reciprocals to produce 15 families. These families were grown in a replicated field trial for 2 years at four rates of applied nitrogen – 0, 225, 450 and 675 kg N/ha – per annum. The data recorded included dry-matter yield, number of fertile and sterile tillers per plant, mean dry weight per fertile and sterile tiller and total dry weights of fertile and sterile tillers. Conventional analyses of variance and diallel analyses were applied to the data as well as path analyses, used to examine the interrelationships between yield and the tiller characters.The main effect of years was significant only for mean dry weights per tiller and dry-matter yield. Increasing the rate of applied nitrogen increased the number of tillers and yields but decreased mean tiller dry weights. Differences between progenies were due to both general and specific combining ability for most characters. Relatively high narrow-sense heritabilities were obtained for the tiller characters although there were differences between the two years.The progenies achieved their yield through different combinations of tiller characters, some having large numbers of fertile tillers with medium dry weights and others having numerous sterile tillers with high dry weights. Although there was inconsistency in the interrelationships between characters, number of tillers was always more important in determining yield than mean dry weight per tiller.The results are discussed in relation to the predictive value of tiller characters on yields and the implications for breeding programmes.

GENETIC CONTROL OF VARIATION IN A SELECTED POPULATION OF ALTAI WILD RYEGRASS (ELYMUS ANGUSTUS)

1979 ◽  
Vol 59 (1) ◽  
pp. 7-13 ◽  
Author(s):  
T. LAWRENCE
Keyword(s):  
Dry Matter ◽  
Direct Selection ◽  
Adult Plant ◽  
Dry Matter Yield ◽  
Appearance Rate ◽  
Leaf Appearance Rate ◽  
Seedling Characters ◽  
Leaf Appearance ◽  
Additive Control ◽  
Rate Of Leaf Appearance

Progenies from a six-genotype diallel cross in Altai wild ryegrass (Elymus angustus Trin.) were studied to assess the pattern of genetic control for F1 seed weight and a number of seedling and adult plant characters. Variation in F1 seed weight was largely determined by the maternal parent, but some control by the pollen parent was apparent. Gene action was additive, but some nonadditive genetic effects were also present. All of the seedling characters, days to emerge, rate of leaf appearance, rate of tiller appearance and seedling dry matter yield showed additive control which is amenable to direct selection. Diallel analyses indicated that the adult plant characters, days to inflorescence appearance, digestible organic matter, total dry matter yield and total seed yield were controlled by strong additive control which is amenable to direct selection. The seedling characters, rate of leaf appearance, rate of tiller appearance and seedling dry matter yield were interrelated but only rate of tiller appearance was associated with adult plant yield.

Low rates of phosphorus fertiliser applied strategically throughout the growing season under rain-fed conditions did not affect dry matter production of perennial ryegrass (Lolium perenne L.)

2010 ◽  
Vol 61 (5) ◽  
pp. 353 ◽  
Author(s):  
L. L. Burkitt ◽  
D. J. Donaghy ◽  
P. J. Smethurst
Keyword(s):  
Lolium Perenne ◽  
Perennial Ryegrass ◽  
Dry Matter ◽  
Growing Season ◽  
Dry Matter Production ◽  
Pasture Production ◽  
Lolium Perenne L ◽  
Matter Production ◽  
Extractable P ◽  
Intensively Managed

Pasture is the cheapest source of feed for dairy cows, therefore, dairy pastures in Australia are intensively managed to maximise milk production and profits. Although soil testing commonly suggests that soils used for dairy pasture production have adequate supplies of phosphorus (P), many Australian dairy farmers still apply fertiliser P, often by applying smaller rates more frequently throughout the year. This study was designed to test the hypotheses that more frequent, but lower rates of P fertiliser applied strategically throughout the growing season have no effect on dry matter production and P concentration in perennial ryegrass (Lolium perenne L.), when soil extractable P concentrations are above the critical value reported in the literature. Three field sites were established on rain-fed dairy pasture soils ranging in P sorption capacity and with adequate soil P concentrations for maximising pasture production. Results showed that applied P fertiliser had no effect on pasture production across the 3 sites (P > 0.05), regardless of rate or the season in which the P was applied, confirming that no P fertiliser is required when soil extractable P concentrations are adequate. This finding challenges the viability of the current industry practice. In addition, applying P fertiliser as a single annual application in summer did not compromise pasture production at any of the 3 sites (P > 0.05), which supports the current environmental recommendations of applying P during drier conditions, when the risk of surface P runoff is generally lower. The current results also demonstrate that the short-term cessation of P fertiliser application may be a viable management option, as a minimal reduction in pasture production was measured over the experimental period.

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