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

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.

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

Genetics Research ◽

10.1017/s001667230001051x ◽

1967 ◽

Vol 9 (2) ◽

pp. 233-245 ◽

Cited By ~ 6

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.

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Responses to selection for seed weight and seedling vigour in Phalaris

Australian Journal of Agricultural Research ◽

10.1071/ar9740033 ◽

1974 ◽

Vol 25 (1) ◽

pp. 33 ◽

Cited By ~ 4

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.

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Developmental genetics of leaf formation in Lolium 3. Inheritance of a developmental complex

Genetics Research ◽

10.1017/s001667230000224x ◽

1970 ◽

Vol 16 (1) ◽

pp. 17-28 ◽

Cited By ~ 5

Author(s):

K. J. R. Edwards

Keyword(s):

Leaf Area ◽

Leaf Size ◽

Leaf Length ◽

Developmental Genetics ◽

Time Interval ◽

Total Leaf Area ◽

Total Leaf ◽

Leaf Formation ◽

Leaf Appearance ◽

Rate Of Leaf Appearance

SUMMARYUsing four lines derived from a single base population of Lolium perenne by selection for large leaf size (LL), small leaf size (SL), fast rate of leaf appearance (FR), and slow rate of leaf appearance (SR), the inheritance of a number of related characters specifying various aspects of leaf development was studied. F1 and F2 generations were produced for all possible crosses between these four lines.The genetic differences between the selection lines were largely additive for all characters studied and entirely so for rate of leaf appearance, duration of elongation of a single leaf and for the time interval between the maturation of leaf 3 and the unfolding of the next youngest leaf on the same side of the apex, leaf 5. The non-additive variances noted in rate of total leaf area formation, individual leaf size and its components length and width, and in the rate of leaf elongation, were associated with a tendency towards heterosis in these characters. This was quite marked in some crosses and tended to be larger for the more complex characters, rate of total leaf area formation and leaf size, suggesting that the heterosis was, to a considerable extent, due to interactions between genes controlling component characters.The data confirmed the earlier finding that the negative correlated selection response between leaf size and rate of leaf appearance was due to a basic association between the maturation of a leaf and the unfolding (onset of rapid elongation) of the next youngest leaf on the same side of the apex. Thus an increase in rate of leaf appearance reduces the duration of elongation of a leaf and this in turn will reduce leaf length. However, the basic association, which seems to be controlled by vascular development of the young leaf, is not entirely invariate.

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

Canadian Journal of Plant Science ◽

10.4141/cjps80-073 ◽

1980 ◽

Vol 60 (2) ◽

pp. 501-508 ◽

Cited By ~ 2

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.

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The growth and development of cowpeas (Vigna unguiculata) under tropical field conditions: 1. Leaf area

The Journal of Agricultural Science ◽

10.1017/s0021859600037977 ◽

1979 ◽

Vol 93 (2) ◽

pp. 291-307 ◽

Cited By ~ 26

Author(s):

E. J. Littleton ◽

M. D. Dennett ◽

J. Elston ◽

J. L. Monteith

Keyword(s):

Leaf Area ◽

Leaf Growth ◽

Leaf Size ◽

Constant Number ◽

Area Index ◽

Number Of Leaves ◽

The Mean ◽

Leaf Appearance ◽

Rate Of Leaf Appearance ◽

Ibadan Nigeria

SUMMARYThe pattern of leaf growth and death was followed in stands of cowpea grown in the field at Ibadan, Nigeria. Temperature affected this pattern. Leaf area index increased quicker and leaf death started sooner during warm seasons. Individual leaves died while pods at the same node were filling. The rate of leaf appearance increased with temperature and the duration of expansion of individual leaves decreased so that a constant number of leaves were expanding at one time. The mean rate of expansion of individual leaves increased with temperature proportionately more than the duration decreased, hence final leaf size increased with temperature. Base temperatures for leaf appearance and leaf expansion were 16 and 20 °C respectively.

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Correlated response to selection for litter size in pigs: II. Carcass, meat, and fat quality traits

Journal of Animal Science ◽

10.2527/2002.80102566x ◽

2002 ◽

Vol 80 (10) ◽

pp. 2566 ◽

Cited By ~ 7

Author(s):

J. Estany ◽

D. Villalba ◽

M. Tor ◽

D. Cubiló ◽

J. L. Noguera

Keyword(s):

Litter Size ◽

Correlated Response ◽

Quality Traits ◽

Response To Selection ◽

Fat Quality ◽

Selection For

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Effects of nitrogen on development and growth of the leaves of vegetables. 3. Appearance and expansion growth of leaves of spinach

Netherlands Journal of Agricultural Science ◽

10.18174/njas.v43i2.580 ◽

1995 ◽

Vol 43 (2) ◽

pp. 247-260

Author(s):

H. Biemond

Keyword(s):

Leaf Area ◽

Leaf Size ◽

Field Trials ◽

Leaf Expansion ◽

Mature Leaf ◽

Leaf Emergence ◽

Number Of Leaves ◽

Leaf Appearance ◽

Rate Of Leaf Appearance ◽

Main Factor

In a series of greenhouse and field trials, spinach cv. Trias plants were supplied with different amounts of N fertilizer in various split applications. Rates of leaf emergence and expansion were recorded, as well as final leaf size. The rate of leaf appearance varied between 0.16 and 0.57/day across experiments, but was hardly affected by N treatment. The rate of leaf expansion and mature leaf area increased with leaf number, reaching maximum values at leaf pair 3+4 or 5+6 and decreasing subsequently. Both characteristics were positively correlated with N supply. The duration of expansion was not influenced by N treatments and varied between 15 and 30 days in most experiments. The rate of leaf expansion was the main factor determining mature leaf size. Specific leaf area over all green leaves slowly decreased with time in most experiments and was around 300 cmsuperscript 2/g. As the differences in the number of leaves were small, the differences in total green leaf area per plant resulted from differences in the areas of individual mature leaves.

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