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.

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.

Distribution of Trialeurodes vaporariorum and Bemisia tabaci (Homoptera: Aleyrodidae) on Some Greenhouse-grown Ornamental Plants

1993 ◽  
Vol 28 (1) ◽  
pp. 102-112 ◽  
Author(s):  
Tong-Xian Liu ◽  
Ronald D. Oetting ◽  
G. David Buntin
Keyword(s):  
Bemisia Tabaci ◽  
Developmental Stages ◽  
Ornamental Plants ◽  
Leaf Age ◽  
Trialeurodes Vaporariorum ◽  
Middle Aged ◽  
Greenhouse Whitefly ◽  
Whole Plant ◽  
Young Leaves ◽  
The Vertical Distribution

The within-plant and between-plant distributions of all stages of both greenhouse whitefly (GHWF), Trialeurodes vaporariorum (Westwood) on poinsettia, chrysanthemum and gerbera daisy, and sweetpotato whitefly (SPWF), Bemisia tabaci (Gennadius) on poinsettia, were examined using Taylor's power law (s2 = amb) and Iwao's patchiness () methods. We found that all developmental stages of the two whitefly species on all plants examined were aggregated within and between plants. The vertical distribution of whitefly stages is stratified among leaves within the plant with respect to leaf age rather than relative height of the leaves on the plants. Most of the adults, eggs and the first-instar nymphs occurred on young leaves. The second- and third-instar nymphs occurred on middle-aged leaves, and most of the pupae and empty pupal cases occurred on middle-aged and older leaves. Comparison of whitefly counts from the different combinations of top, middle, and bottom leaves with the whole-plant counts on poinsettia was correlated and these leaves can be sampled as an indication of population levels within a greenhouse population.

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 On the Capability of the Epigeous Organs of Phragmites australis to Act as Metal Accumulators in Biomonitoring Studies

2021 ◽  
Vol 13 (14) ◽  
pp. 7745
Author(s):  
Daniela Baldantoni ◽  
Alessandro Bellino
Keyword(s):  
Phragmites Australis ◽  
Littoral Zone ◽  
Metal Accumulation ◽  
Leaf Age ◽  
Common Reed ◽  
Volcanic Lake ◽  
Whole Plant ◽  
Age Dependent ◽  
Young Leaves ◽  
Plant Exposure

With a view of shedding light on the accumulation capability of the epigeous organs of common reed (Phragmites australis), employed worldwide in metal biomonitoring, an accumulation study of Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn was performed, focusing on leaves belonging to different whorls and culms. To this end, in five sampling sites on the littoral zone of the volcanic Lake Averno (Italy), and in one occasion (autumn) before plant senescence, leaves of different ages and culms were collected and analyzed for metal concentrations. In terms of the suitability for biomonitoring, culms demonstrated poor performances in relation to the low metal accumulation and the difficulties in sampling and processing, whereas leaves proved their effectiveness in highlighting whole plant exposure. Since the accumulation degree of Cr, Cu, Fe and Zn is unaffected by leaf age, the pooling of leaves from different whorls is advisable to improve the representativeness of samplings. This strategy becomes mandatory in the case of Ni, the non-monotonic age-dependent variations of which would affect the derivation of contamination gradients otherwise. For Mn, Cd and Pb, the accumulation patterns strictly dependent on age can instead be exploited in selecting the sensitivity of biomonitoring by focusing on the organs where they are preferentially accumulated: old leaves for Mn and young leaves for Cd and Pb.

Diagnosis of potassium deficiency in faba bean and chickpea by plant analysis

1998 ◽  
Vol 38 (5) ◽  
pp. 503 ◽  
Author(s):  
N. Aini ◽  
C. Tang
Keyword(s):  
Faba Bean ◽  
Shoot Growth ◽  
Leaf Age ◽  
Critical Values ◽  
Plant Age ◽  
Plant Parts ◽  
Young Leaves ◽  
K Deficiency ◽  
K Concentration ◽  
Shoot Weight

Summary. Critical potassium (K) concentrations for the diagnosis of K deficiency were determined in various shoot parts of faba bean (Vicia faba L. cv. Fiord) and chickpea (Cicer arietinum L. T1587) plants grown at K rates of 0–240 mg K/kg in a K-deficient soil in the glasshouse. Shoot growth of both species increased with rates of K applied and with plant age but faba bean was more responsive to K application than chickpea. Potassium concentrations in plant parts greatly increased with increasing K supply. In faba bean, K concentrations in all shoot parts decreased with plant age irrespective of K supply while in chickpea K concentrations in leaves of K-deficient plants increased with plant age but those in stems decreased. For both species, young leaves had higher K concentrations than old tissues, especially in K-deficient plants. A greater proportion of leaf K was stored in the petioles when K supply was adequate than when K was deficient. Critical K concentrations were determined using the hand-fitted curve and Mitscherlich model at 90% maximum shoot weight and the 2-phase linear model. The critical concentrations varied between plant parts and among the methods used. Critical values decreased with leaf age and were higher in leaf petioles than in leaf blades. Critical K concentrations, developed from hand-fitted curves, in the 1st plus 2nd and 3rd plus 4th leaf blades of faba bean, and leaf petioles below the youngest fully expanded leaf (YFEL) of chickpea were similar between days 48 and 73 for faba bean and between days 55 and 80 for chickpea. It is recommended that the critical values for the diagnosis of K deficiency at 7–8-leaf stages are 1.3–1.5% in YFEL, 1.1–1.2% in the 1st plus 2nd leaf blades below the YFEL and 1.8–2.0% in whole shoot of faba bean, and 1.4–1.5% in YFEL, 2.7–2.8% in the 1st plus 2nd leaf petioles and 2.1–2.2% in whole shoot of chickpea. The gradient of K concentration between young and old leaves occurred before a decrease in shoot growth and may be used for the prognosis of K deficiency.

scholarly journals Effect of Leaf and Plant Age, and Day/Night Temperature on Net CO2 Uptake in Phalaenopsis amabilis var. formosa

2006 ◽  
Vol 131 (3) ◽  
pp. 320-326 ◽  
Author(s):  
Woei-Jiun Guo ◽  
Nean Lee
Keyword(s):  
Photosynthetic Efficiency ◽  
Leaf Age ◽  
High Light Intensity ◽  
Plant Age ◽  
Photon Flux ◽  
Co2 Uptake ◽  
Night Temperature ◽  
Mature Leaves ◽  
Temperature Regimes ◽  
Young Leaves

In this study, effects of leaf age (20 to 240 days), plant age (4, 8, and 14 months after deflasking), and various day/night temperature regimes (16 to 33 °C) on photosynthesis of Phalaenopsis amabilis L. Blume var. formosa Shimadzu (Phal. TS97) leaves were investigated. The diurnal net CO2 uptake in Phal. TS97 leaves was measured and integrated to obtain total net CO2 uptake, which represents photosynthetic efficiency in plants performing crassulacean acid metabolism (CAM). Under all conditions, Phal. TS97 leaves performed typical CAM photosynthesis and reached their highest net CO2 uptake rate, ≈6 μmol·m-2·s-1, after 3 to 4 hours in the dark under a 12-hour photoperiod. When grown under 30 °C day/25 °C night temperature, the total net CO2 uptake of leaf increased with maturation and was highest at 80 days old, 20 days after full expansion. The CAM photosynthetic capacity of mature leaves remained high after maturation and began to decline at a leaf age of 240 days. The trend was consistent with malate fixation but the highest nocturnal malate concentration was observed in 100-day-old leaves. Young leaves or leaves from small juvenile plants had higher daytime CO2 fixation compared to mature leaves or large plants, suggesting that Phal. TS97 leaves progressed from C3-CAM to CAM during the course of maturation. The second newly matured leaf from the top had the highest net CO2 fixation when the newest leaf was 8 cm in length. Although plant age did not influence total CO2 uptake in the leaf, photosynthetic efficiency of leaves in small younger plants was more sensitive to high light intensity, 340 μmol·m-2·s-1 photosynthetic photon flux. The day/night temperature of 32/28 and 29/25 °C resulted in the highest total net CAM CO2 fixation in vegetative Phal. TS97 plants than higher (33/29 °C) and lower temperatures (21/16 °C).

EPTC Plus R-25788 Injury to Corn (Zea Mays) as Affected by Plant Age at Treatment

Weed Science ◽  
1979 ◽  
Vol 27 (4) ◽  
pp. 460-462 ◽  
Author(s):  
G. W. Burt ◽  
C. A. Buzio
Keyword(s):  
Zea Mays ◽  
Plant Height ◽  
Plant Age ◽  
Entire Period ◽  
Respective Control ◽  
Height Reduction ◽  
Stages Of Growth ◽  
Greenhouse Study ◽  
Herbicide Treatment

The susceptibility of corn (Zea maysL. ‘Pioneer 3334A’) at different stages of growth to EPTC (S-ethyl dipropylthiocarbamate) plus a herbicide-protectant, R-25788 (N,N-diallyl-2,2-dichloroacetamide), was studied in the greenhouse. Corn was treated with either 25 ppm or 12.5 ppm EPTC containing R-25788 at planting and at 2, 4, 6, and 8 weeks thereafter. The herbicide was soil-applied and immediately incorporated by watering. Phytotoxicity and plant height were observed periodically for 56 days after herbicide treatment. Within 21 days after treatment with 25 ppm EPTC containing R-25788, injury and plant height reduction occurred in corn treated at planting, or at 2 and 4 weeks but not at 6 or 8 weeks after planting. At 56 days, however, corn treated at planting or 2 weeks after planting had outgrown all injury symptoms and was as tall as the controls (>84%). Corn treated at 4 weeks after planting, however, still remained injured and was 45% as tall as its respective control. Corn treated at 6 to 8 weeks showed no injury during the entire period of observations. The data indicates that corn is most susceptible to EPTC plus R-25788 at 4 weeks after planting. The results of this greenhouse study are discussed in relation to corn injury as observed in the field.

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.

Sign in / Sign up

Export Citation Format

Share Document