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.

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 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.

scholarly journals Unveiling a unique genetic diversity of cultivated Coffea arabica L. in its main domestication center: Yemen

2021 ◽  
Author(s):  
C. Montagnon ◽  
A. Mahyoub ◽  
W. Solano ◽  
F. Sheibani
Keyword(s):  
Genetic Diversity ◽  
Genetic Distance ◽  
Coffea Arabica ◽  
Genetic Improvement ◽  
The World ◽  
Genetic Clusters ◽  
Domestication Process ◽  
Almost All ◽  
Coffea Arabica L ◽  
Cup Quality

AbstractWhilst it is established that almost all cultivated coffee (Coffea arabica L.) varieties originated in Yemen after some coffee seeds were introduced into Yemen from neighboring Ethiopia, the actual coffee genetic diversity in Yemen and its significance to the coffee world had never been explored. We observed five genetic clusters. The first cluster, which we named the Ethiopian-Only (EO) cluster, was made up exclusively of the Ethiopian accessions. This cluster was clearly separated from the Yemen and cultivated varieties clusters, hence confirming the genetic distance between wild Ethiopian accessions and coffee cultivated varieties around the world. The second cluster, which we named the SL-17 cluster, was a small cluster of cultivated worldwide varieties and included no Yemen samples. Two other clusters were made up of worldwide varieties and Yemen samples. We named these the Yemen Typica-Bourbon cluster and the Yemen SL-34 cluster. Finally, we observed one cluster that was unique to Yemen and was not related to any known cultivated varieties and not even to any known Ethiopian accession: we name this cluster the New-Yemen cluster. We discuss the consequences of these findings and their potential to pave the way for further comprehensive genetic improvement projects for the identification of major resilience/adaptation and cup quality genes that have been shaped through the domestication process of C. arabica.

scholarly journals Meteorological conditions, ozone concentration and leaf age affect gas exchange in Psidium guajava ‛Palumaʼ

Hoehnea ◽  
2017 ◽  
Vol 44 (2) ◽  
pp. 236-245 ◽  
Author(s):  
Juliana Moreno Pina ◽  
Sérgio Tadeu Meirelles ◽  
Regina Maria de Moraes
Keyword(s):  
Gas Exchange ◽  
Ozone Concentration ◽  
Leaf Age ◽  
Psidium Guajava ◽  
Meteorological Conditions ◽  
Gas Exchanges ◽  
Mature Leaves ◽  
Young Leaves ◽  
Entire Experiment ◽  
The City

ABSTRACT This study aimed to investigate the importance of leaf age, meteorological conditions and ozone concentration (O3) on gas exchange of Psidium guajava ‛Paluma'. Saplings were grown and exposed in standard conditions in the city of São Paulo, in six periods of three months with weekly measurements in young and mature leaves. Gas exchanges were higher in young leaves for almost the entire experiment. Mature leaves showed greater reduction in gas exchange. The multivariate analysis of biotic and abiotic variables indicated that vapor pressure deficit (VPD), O3 concentration and radiation were the main variables associated with gas exchange decrease in young leaves. In mature leaves the influence of VPD is lower, but the temperature importance is higher. Moreover, the opposition between assimilation and O3 is more evident in mature leaves, indicating their greater sensitivity to O3.

scholarly journals Distribution and pathogenicity of Pseudomonas cichorii (Swingle) Stapp in coffee in Puerto Rico

1969 ◽  
Vol 87 (3-4) ◽  
pp. 123-135 ◽  
Author(s):  
Luis Sánchez ◽  
Mildred Zapata ◽  
Rocío del P. Rodríguez ◽  
James S. Beaver
Keyword(s):  
Puerto Rico ◽  
Leaf Age ◽  
Coffea Canephora ◽  
Resistance Mechanisms ◽  
Pseudomonas Cichorii ◽  
Inoculation Methods ◽  
Young Leaves ◽  
Resistant Genotypes ◽  
Coffee Species

Seventeen pathogenic strains of Pseudomonas cichorii were isolated from leaf samples of coffee (Coffea arabica) collected from nurseries in eight municipalities of Puerto Rico. Two different inoculation methods were evaluated under in vitro conditions: inoculation of plant-attached old and young leaves grown under greenhouse conditions, and plant-detached young coffee leaves grown under field conditions. Pseudomonas cichorii was more virulent in older leaves, thus indicating that resistance mechanisms differ according to leaf age. Both inoculation methods were reliable in identifying resistant genotypes. Three commercial varieties of coffee (Borbón, Pacas and Caturra) were susceptible to bacterial leaf blight, whereas coffee species Coffea liberica var. Excelsa and Coffea canephora var. Robusta were resistant.

scholarly journals Occurrence of Alternaria dichondrae, Cercospora sp., and Puccinia sp. on Dichondra repens in France and Italy

Plant Disease ◽  
2005 ◽  
Vol 89 (9) ◽  
pp. 1012-1012 ◽  
Author(s):  
L. Cardin ◽  
B. Delecolle ◽  
B. Moury
Keyword(s):  
Fungal Pathogens ◽  
Poa Pratensis ◽  
Rust Fungus ◽  
Lower Surface ◽  
Mycelium Growth ◽  
Disease Symptoms ◽  
Public Gardens ◽  
Perennial Plant ◽  
Young Leaves ◽  
Necrotic Spots

Dichondra repens (kidneyweed or ponysfoot), family Convolvulaceae, is a perennial plant with persistent leaves and is grown alone or in association with turfgrass in subtropical and Mediterranean regions. Because of its prostrate growth habit, it does not need to be mowed. It is also used as a potted plant for house decoration. During surveys of lawns in public gardens of the Franco-Italian Riviera conducted from 1993 to 2003, we noticed 0.1- to 0.5-cm-diameter, brownish, necrotic spots on leaves of D. repens in Antibes, Cannes, Menton, Nice, and Vallauris (France) and in Arma di Taggia, Diano Marina, Imperia, La Mortola, Ospedaletti, San Remo, and Ventimiglia (Italy). Symptoms were more intense in the spring on young leaves but lesions remained all year on older leaves. Two species of fungal pathogens were frequently isolated from these spots. One fungus produced brown, erect conidiophores with brown, pear-shaped conidia and bifid, subhyaline beaks. Conidia formed singly, were composed of 8 to 10 cells with transverse and longitudinal crosswalls, and had one to four hyaline spurs frequently longer than the conidia. Conidia measured 90 to 260 × 16 to 29 μm. The pathogen, identified as Alternaria dichondrae (1), was previously characterized in Italy, New Zealand, and Argentina. The second fungus species produced clumps of erect, brown conidiophores with hyaline, filiform conidia composed of 10 to 20 cells. These conidia measured 90 to 310 × 3 to 3.5 μm. This fungus was identified as a Cercospora sp. (2), a genus not previously reported on D. repens. For both fungi, necrotic spots similar to those observed in natural infections were obtained after spraying a suspension of mycelium and conidia onto leaves of D. repens seedlings that had two to four expanded leaves that had been pricked with a pin. The plants were maintained under high humidity. Assays of mycelium growth on agar media containing various fungicides showed that 1 ppm of pyremethanil completely inhibited the growth of A. dichondrae, whereas a mixture of 10 ppm of diethofencarb and 10 ppm of carbendazine completely inhibited Cercospora sp. growth. Telia were also observed on the lower surface of D. repens leaves, sometimes in association with disease symptoms of A. dichondrae and Cercospora sp. Disease symptoms of the rust were yellowing and curling of the leaf surface with erect petiole, whereas healthy plants were prostrate with plane leaf surfaces. The two-celled teliospores had smooth cell walls, a single germinative pore per cell, and measured 32 to 34 × 12 to 13 μm with a thin unattached pedicel. This rust fungus was consequently classified in the genus Puccinia (2), also not previously reported as a pathogen of D. repens. It is possible that Poaceae plants such as Poa pratensis grown in association with D. repens were the inoculum source. Whereas A. dichondrae and Cercospora sp. do not induce severe diseases and are not widespread, the prevalence of Puccinia sp. tends to increase over time, requiring appropriate treatments to manage infected turf grasses. References: (1) P. Gambogi et al. Trans. Br. Mycol. Soc. 65:322, 1975. (2) G. Viennot-Bourgin. Les Champignons Parasites des Plantes Cultivées, Masson ed. Paris, 1949.

Photosynthetic response of geranium to elevated CO2 as affected by leaf age and time of CO2 exposure

1991 ◽  
Vol 69 (11) ◽  
pp. 2482-2488 ◽  
Author(s):  
D. W. Kelly ◽  
P. R. Hicklenton ◽  
E. G. Reekie
Keyword(s):  
Stomatal Density ◽  
Leaf Age ◽  
Net Photosynthesis ◽  
Leaf Thickness ◽  
Middle Aged ◽  
Future Studies ◽  
Structural Modifications ◽  
Young Leaves ◽  
Developmental Characteristics ◽  
Density Results

Geranium plants were grown from seed in chambers maintained at 350 or 1000 μL∙L−1 CO2. Phtopsynthesis as affected by leaf age and by leaf position was determined. Elevated CO2 enhanced photosynthesis to the greatest extent in middle-aged leaves; very young leaves exhibited little enhancement, and net photosynthesis in the oldest leaves was depressed by elevated CO2. Temporary increases in net photosynthesis (relative to leaves developed at high CO2) resulted when young leaves grown at 350 μL∙L−1 CO2 were switched to 1000 μL∙L−1 CO2. Leaves switched later in development exhibited permanent enhancement. Middle-aged leaves exhibited a temporary depression followed by permanent enhancement. Leaves developed at high CO2 and switched to low CO2 did not exhibit any photosynthetic depression relative to plants grown continuously at low CO2. Similarly, leaves developed at low CO2, switched to high CO2 for various lengths of time, and returned to low CO2 showed no photosynthetic depression. Leaves developed at low CO2 and switched to high CO2 exhibited increases in specific leaf weight and leaf thickness. The increase in leaf thickness was proportional to length of time spent at high CO2. High CO2 depressed the rate at which stomata developed but did not affect final stomatal density. Results suggest that photosynthesis at low CO2 was limited by CO2 regardless of developmental environment, whereas photosynthesis at high CO2 was limited by the developmental characteristics of the leaf. Further, both biochemical and structural modifications appear to be involved in this response. Because of the very different responses of young versus old leaves, future studies should be careful to consider leaf age in assessing response to elevated CO2. Key words: carbon dioxide, elevated CO2, photosynthesis, geranium.

scholarly journals Differential responses between mature and young leaves of sunflower plants to oxidative stress caused by water deficit

2010 ◽  
Vol 40 (6) ◽  
pp. 1290-1294 ◽  
Author(s):  
Inês Cechin ◽  
Natália Corniani ◽  
Terezinha de Fátima Fumis ◽  
Ana Catarina Cataneo
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Leaf Gas Exchange ◽  
Intercellular Co2 Concentration ◽  
Leaf Age ◽  
Co2 Concentration ◽  
Mature Leaves ◽  
Young Leaves ◽  
Mda Content ◽  
Gas Exchange Characteristics

The effects of water stress and rehydration on leaf gas exchange characteristics along with changes in lipid peroxidation and pirogalol peroxidase (PG-POD) were studied in mature and in young leaves of sunflower (Helianthus annuus L.), which were grown in a greenhouse. Water stress reduced photosynthesis (Pn), stomatal conductance (g s), and transpiration (E) in both young and mature leaves. However, the amplitude of the reduction was dependent on leaf age. The intercellular CO2 concentration (Ci) was increased in mature leaves but it was not altered in young leaves. Instantaneous water use efficiency (WUE) in mature stressed leaves was reduced when compared to control leaves while in young stressed leaves it was maintained to the same level as the control. After 24h of rehydration, most of the parameters related to gas exchange recovered to the same level as the unstressed plants except gs and E in mature leaves. Water stress did not activated PG-POD independently of leaf age. However, after rehydration the enzyme activity was increased in mature leaves and remained to the same as the control in young leaves. Malondialdehyde (MDA) content was increased by water stress in both mature and young leaves. The results suggest that young leaves are more susceptible to water stress in terms of gas exchange characteristics than mature leaves although both went through oxidative estresse.

scholarly journals XIX. Abstract of a register of the barometer, thermometer, and rain, at Lyndon, in Rutland, 1794

1795 ◽  
Vol 85 ◽  
pp. 410-413
Keyword(s):  
Good Deal ◽  
The South ◽  
Great Abundance ◽  
Warm Weather ◽  
Young Leaves ◽  
Strong Winds ◽  
Calm Weather ◽  
Almost All

The year began with frost, but a broken one, neither severe nor settled, with much sun, calm weather and pleasant, yet the ice was scarce gone at the end of January ; in the latter part of the month there were some strong winds, which were more frequent afterward; showery, mild, almost without frost, plea­sant and forward. Several autumnal flowers continued in blow all winter; the winter ones were early, and the spring ones forward; many anemonies, which are properly a spring flower, were blowing all winter, but had not then their full colours which they have in their season. This open winter was not a wet one, which was verv convenient, as fodder was scarce, and turnips late and small, but were much mended by the mild autumn. The ground was green almost all winter; and there were very few NE winds in March and April, and there was pretty good grass in that last month, which was a great advantage when a colder season came on in May. Oaks be­gan to be cut soon after the 20th of April, and the hawthorns to blow before the end of the month. With May began a colder season, with frequent frosty mornings, blasting the fruit after it appeared set, and also the young leaves very much, and more northerly winds, espe­cially toward the end of the month, and the former part of June; for they seldom fail of coming sooner or later in the spring ; yet the weather was often fair, fine, and pleasant, but the ground getting too dry. The latter part of June and most of July was remarkably hot, and for the most part burning; but some single large rains in July, particularly toward the end of it, prevented its burning so much here as it did in the south of England, where the drought was greater, and lasted much longer : there they suffered very much by it; but from the forwardness of the beginning of spring we were never without grass, though it was burnt. There were good crops of hay on some of the low moist meadows, but the uplands and late laid were light. The heat of June and July, and middle of August, brought things very forward. Harvest began about July 20, and was nearly finished in August: the crops did not look much amiss upon the ground, but disappointed people, for they yielded badly, especially beans and pease, of which there were very few ; barley and oats were the best; but the scarcity of other things made them also dear. Myrtles flowered very fine this summer, because they began in July, which is sooner than usual; they are apt not to begin till the warm weather is almost over. The harvest was in general well got, but not so well at the end as at the beginning, for there were 18 inches of rain in five months, from July to November; great single rains in July, fits of wet in August and September, and almost daily in October and November, with floods and storms; this made great plenty of grass; but the ground became wet and soft, and much trodden, and the turnips were not so good as might have been expected. The crop of fruit was very uncertain ; in some places it was very scarce, in other places there was a good deal; but in most the apples rotted extremely. The hedge fruits were in great abundance, excepting ash-keys, of which most people said there were none at all.

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