scholarly journals Translocation of 14C-assimilates from Leaves of Strawberry Plants in Vegetative Stage as Affected by Leaf Age and Leaf Position

1986 ◽  
Vol 54 (4) ◽  
pp. 467-476 ◽  
Author(s):  
Takashi NISHIZAWA ◽  
Yutaka HORI
Keyword(s):  
Leaf Age ◽  
Vegetative Stage ◽  
Leaf Position

Recovery From Water Stress in Five Sunflower (Helianthus annuus L.) Cultivars. II. The Development of Leaf Area

1982 ◽  
Vol 9 (4) ◽  
pp. 449 ◽  
Author(s):  
HM Rawson ◽  
NC Turner
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Leaf Area ◽  
Old Age ◽  
Leaf Age ◽  
Leaf Position ◽  
Water Application ◽  
Leaf Emergence ◽  
Young Leaves ◽  
The Difference

Five cultivars of sunflower with different durations to anthesis were grown in the field either entirely on stored soil moisture (DRY), irrigated frequently throughout growth (WET), or transferred from the DRY to the WET regime at 44 days (REC 1) or at 54 days from sowing (REC 2). The expansion patterns of all leaves were followed with a view to determining which leaves responded when stress was relieved. Cultivars differed in their ability to recommence leaf expansion after water was applied to DRY crops, but any differences were related to the stage of plant development reached when water was applied. Thus in the REC 1 treatment, no leaves of early cultivars equalled the areas achieved in equivalent leaves in the WET regime, whereas the latest cultivar generated individual leaves which were 60% larger than equivalent leaves in the WET treatment. In the REC 2 treatment, few leaves of the early cultivars reached significantly larger areas than equivalent leaves in the DRY while all leaves above node 12 in the latest cultivar exceeded those in the DRY regime. Examining the data in terms of the age of leaves in the profile when the REC 1 and REC 2 treatments were applied showed that, regardless of cultivar, all leaves which were less than 15 days old (age 0 = leaf emergence) had some capacity for renewed expansion when water was applied. However, primordia which still had 15 days to go before they emerged as leaves had the greatest capacity for expansion to a potential size, and this capacity decreased progressively over their next 30 days of aging. Leaf age profiles did not explain all the difference in renewed expansion potential among cultivars: a leaf position factor at the time of water application was almost as important. Thus, the closer that leaves were to the head, the less was their capacity for renewed expansion regardless of their age. In order to achieve larger areas when water was applied, old leaves increased their duration of expansion while young leaves increased their rate of expansion. It is concluded that cultivars do not differ in their ability to 'recover' leaf area upon application of water except by virtue of their different durations to anthesis.

scholarly journals Leaf Position Prevails Over Plant Age and Leaf Age in Reflecting Resistance to Late Blight in Potato

2003 ◽  
Vol 93 (6) ◽  
pp. 666-674 ◽  
Author(s):  
M. H. P. W. Visker ◽  
L. C. P. Keizer ◽  
D. J. Budding ◽  
L. C. Van Loon ◽  
L. T. Colon ◽  
...  
Keyword(s):  
Late Blight ◽  
Leaf Age ◽  
Late Blight Resistance ◽  
Plant Age ◽  
Blight Resistance ◽  
Controlled Environment ◽  
General Effect ◽  
Leaf Position ◽  
Nonspecific Resistance ◽  
Growing Conditions

The effects of plant age, leaf age, and leaf position on race-nonspecific resistance against Phytophthora infestans were investigated in a series of field and controlled environment experiments with five different potato (Solanum tuberosum) cultivars. Leaf position proved to be the most significant factor; apical leaves were far more resistant to late blight than basal leaves. Plant age and leaf age had only minor effects; therefore, the resistance of a specific leaf remained about the same during its entire lifetime. The gradual increase in late blight resistance from basal leaves to apical leaves appeared to be a general effect, irrespective of cultivar, growing conditions, or resistance test. Therefore, it is important to consider leaf position in tests for late blight resistance, because contrasts in resistance may be ascribed erroneously to differences between genotypes or treatments, whereas they are actually caused by differences in leaf position.

Mite association with the leaf domatia of coffee (Coffea arabica) in north Queensland, Australia

1994 ◽  
Vol 84 (3) ◽  
pp. 361-366 ◽  
Author(s):  
Dennis J. O'Dowd
Keyword(s):  
Coffea Arabica ◽  
Fungal Pathogens ◽  
Leaf Age ◽  
Leaf Position ◽  
Primary Vein ◽  
Far North ◽  
Mite Reproduction ◽  
Young Leaves ◽  
Arthropod Pests ◽  
Almost All

AbstractThe primary coffee of commerce, Coffea arabica, has well-developed pit domatia in the primary vein axils on the undersurfaces of the leaves. In plantations near Mareeba and Daintree in far north Queensland, Australia, these morphogenetic structures are commonly occupied by mites. Mites used domatia on over 80% of all leaves examined, and 41% of all domatia had been occupied by mites (15–28% on young leaves and 54–59% on older leaves at Mareeba, and 58% overall at Daintree). At Mareeba, domatia use by mites did not differ among plants or shoots within plants but did vary significantly with leaf position within shoots, a reflection of leaf age. Domatia were important sites for mite reproduction and development; 93% of the eggs and all moulting mites on leaves were in domatia. Seven mite taxa were identified on leaves at Mareeba and nine were present at Daintree. With the exception of Fungitarsonemus sp. and Brevipalpus obovatus Donnadieu at Mareeba, all were concentrated in leaf domatia. Almost all mites in domatia were from groups in which arboreal representatives are primarily predatory (e.g., Stigmaeidae, Phytoseiidae, and Bdellidae), fungivorous (e.g., Winterschmidtiidae, Oribatida and Acaridae), or both (Tydeidae and Tarsonemidae). The data suggest that domatia influence the distribution and abundance of predatory and fungivorous mites that have the potential to affect fungal pathogens and some arthropod pests on coffee leaves.

scholarly journals Effect of Leaf Positions on Total Phenolics, Flavonoids and Proanthocyanidins Content and Antioxidant Activities in Lantana Camara (L)

2009 ◽  
Vol 1 (2) ◽  
pp. 363-369 ◽  
Author(s):  
Deepita Bhakta ◽  
Deepak Ganjewala
Keyword(s):  
Sharp Increase ◽  
Total Phenolics ◽  
Antioxidant Activities ◽  
Leaf Age ◽  
Antioxidant Properties ◽  
Dry Weight ◽  
Lantana Camara ◽  
Scavenging Activity ◽  
Leaf Position ◽  
Fresh Weight

Changes in the level of phenolics, flavonoids and proanthocyanidins with leaf positions were studied in L. camara twigs. Leaves at different positions (from apex to base) in a twig represented gradient increase in the leaf age, apical being the youngest leaves. The study showed that the fresh weight, dry weight and area of the leaves increased rapidly from I until IV position in a twig. Levels of phenolics remained unchanged from I to V leaf position, while a sharp increase in the levels of proanthocyanidins and flavonoids was observed during I to III leaf position which decreased markedly thereafter. At any leaf position in a twig, the level of proanthocynidin was higher than both phenolics and flavonoids, while the proportion of flavonoids was much higher than the phenolics. In fact, phenolics were present in very small amounts. In addition, antioxidant potential of leaves extracts was measured in terms of reducing and scavenging activity. The study revealed that extracts prepared from leaves present from I to III position exhibited significantly higher antioxidant activities than the leaves present from IV to V position. The study thus revealed that leaf positions (age) influence the level of secondary metabolites and thereby their antioxidant properties. Keywords: Antioxidant; Flavonoids; Lantana camara; Phenolics; Proanthocynidins.© 2009 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.DOI: 10.3329/jsr.v1i2.1873

scholarly journals Effect of plant age, leaf age and leaf position on infection of carrot leaves by Cercospora carotae

2005 ◽  
Vol 74 (2) ◽  
pp. 75-87 ◽  
Author(s):  
A. Van Delden ◽  
O. Carisse
Keyword(s):  
Incubation Period ◽  
Leaf Age ◽  
Relative Number ◽  
Plant Age ◽  
Leaf Position ◽  
Initial Development ◽  
Greenhouse Study ◽  
Whole Plant ◽  
Young Leaves ◽  
Cercospora Carotae

A greenhouse study was conducted to determine the effects of plant age, leaf age and leaf position on infection of carrot (Daucus carota var. sativa) by Cercospora carotae. Infection was quantified as the number of lesions cm-2 of leaf surface and the length of incubation period. The relative number of lesions decreased linearly with increasing plant age from 39- to 60-d-old plants, and remained low from 60- to 71-d-old plants. The incubation period increased from 9.0 to 16.6 d, with increasing plant age. Relative number of lesions decreased with increasing leaf age from 1 to 36 d, but the variation among leaves was high. The incubation period increased from 9.0 to 18.3 d with increasing leaf age, but lesions on a few young leaves appeared relatively late. Generally, differences in relative number of lesions for leaves on different positions for 10- and 13-wk-old plants were not significant. Infection on all leaves except the two youngest was representative of infection on whole plant. Effect of leaf position on incubation period was different for the 10- and 13-wk-old plants and for the two trials. Plants younger than 60 d old, in the seven-to eight-leaf stages should be used for experiments on the initial development of Cercospora blight of carrots.

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