Effects of direct contact of Pinus resinosa seeds and young seedlings with 2,4-D or picloram on seedling development

1971 ◽  
Vol 49 (10) ◽  
pp. 1737-1741 ◽  
Author(s):  
Ching Chen Wu ◽  
T. T. Kozlowski ◽  
R. F. Evert ◽  
S. Sasaki
Keyword(s):  
Direct Contact ◽  
Root Elongation ◽  
Callus Formation ◽  
Pinus Resinosa ◽  
Seedling Development ◽  
Abnormal Development ◽  
Intercellular Spaces ◽  
Mesophyll Cells ◽  
Pine Seedlings ◽  
Parenchyma Cells

Effects of 2,4-D and picloram at 50 and 100 ppm on early development of Pinus resinosa seedlings were studied. Both herbicides caused abnormal development of pine seedlings. After seeds germinated, the first conspicuous effect of 2,4-D treatment was cessation of root elongation. Proliferation and expansion of parenchyma cells in the stem and cotyledons were also stimulated by 2,4-D, causing abnormal thickening of seedlings. Disorganization and collapse of parenchyma cells in the upper stem were followed by callus formation. Cotyledons of 2,4-D-treated plants developed abnormally. Formation of vascular strands was retarded. Division and expansion of mesophyll cells were stimulated by 2,4-D causing decrease in intercellular spaces. Numbers of stomata and chloroplasts were lower in cotyledons of treated plants than in controls. Cotyledons of treated plants were fused to primary needles. Expansion of early formed primary needles and initiation and expansion of additional primary needles were inhibited by 2,4-D. Effects of picloram on pine seedlings were somewhat similar to effects of 2,4-D but picloram appeared to be more toxic at comparable dosages.

Effect of pretreatment of pine seeds with herbicides on seed germination and growth of young seedlings

1968 ◽  
Vol 46 (3) ◽  
pp. 255-262 ◽  
Author(s):  
S. Sasaki ◽  
T. T. Kozlowski ◽  
J. H. Torrie
Keyword(s):  
Seed Germination ◽  
Pinus Resinosa ◽  
Seedling Development ◽  
Pine Seedlings ◽  
Germination And Growth

The effect of 24-hour pretreatment of Pinus resinosa Ait. seeds with herbicides, before the seeds are planted in soil, was studied on seed germination and seedling development over a 34-day period. Atrazine, simazine, or propazine at 200, 500, or 1000 p.p.m. did not affect seed germination significantly. At 500 and 1000 p.p.m. CDEC and EPTC had little or no effect on seed germination whereas CDAA and 2,4-D markedly inhibited both early and final germination. Atrazine and simazine were very toxic to young pine seedlings, with toxicity proportional to herbicide dosage. In contrast to atrazine and simazine, propazine did not kill seedlings during the 34 days of the experiment. At 500 p.p.m. CDEC and EPTC began to kill young seedlings at 24 days; 2,4-D at 27 days. CDAA, which had suppressed seed germination greatly, did not kill young seedlings. Marked morphogenic changes in seedlings were caused by pretreatment of the seed with EPTC, CDEC, or 2,4-D. CDEC and EPTC caused fused cotyledons; 2,4-D caused swollen stems and shrivelled cotyledons. At about 20 days after planting, the primary leaves of plants whose seeds had been treated with EPTC or CDEC (500 p.p.m.) emerged through a split at the base of the fused cotyledons. Higher dosages of these herbicides suppressed emergence of primary needles.

Effects of root zone temperature on root initiation and elongation in red pine seedlings

1986 ◽  
Vol 16 (4) ◽  
pp. 696-700 ◽  
Author(s):  
Chris P. Andersen ◽  
Edward I. Sucoff ◽  
Robert K. Dixon
Keyword(s):  
Root Elongation ◽  
Root Zone ◽  
Soluble Sugar ◽  
Soluble Sugars ◽  
Red Pine ◽  
Root Tip ◽  
Root Initiation ◽  
Root Zone Temperature ◽  
Pine Seedlings ◽  
Zone Temperature

The influence of root zone temperature on root initiation, root elongation, and soluble sugars in roots and shoots was investigated in a glasshouse using 2-0 red pine (Pinusresinosa Ait.) seedlings lifted from a northern Minnesota nursery. Seedlings were potted in a sandy loam soil and grown in chambers where root systems were maintained at 8, 12, 16, or 20 °C for 27 days; seedling shoots were exposed to ambient glasshouse conditions. Total new root length was positively correlated with soil temperature 14, 20, and 27 days after planting, with significantly more new root growth at 20 °C than at other temperatures. The greatest number of new roots occurred at 16 °C; the least, at 8 °C. Total soluble sugar concentrations in stem tissue decreased slightly as root temperature increased. Sugar concentrations in roots were similar at all temperatures. The results suggest that root elongation is suppressed more than root tip formation when red pine seedlings are exposed to the cool soil temperatures typically found during spring and fall outplanting.

scholarly journals Comparative Study on Gas Exchange, Water Relations and Leaf Anatomy of Two Olive Cultivars Grown under Well-Irrigated and Drought Conditions

1999 ◽  
Vol 54 (9-10) ◽  
pp. 688-692 ◽  
Author(s):  
Konstantinos Chartzoulakis ◽  
Angelos Patakas ◽  
Artemis Bosabalidis
Keyword(s):  
Gas Exchange ◽  
Water Relations ◽  
Volume Fraction ◽  
Spongy Parenchyma ◽  
Intercellular Spaces ◽  
Palisade Parenchyma ◽  
Mesophyll Cells ◽  
Olive Cultivars ◽  
Olea Europea ◽  
Leaf Anatomical Characteristics

The effect of water stress on gas exchange, water relations and leaf anatomical characteristics have been studied in two olive cultivars (Olea europea, L. cv. ‘Koroneiki’ and cv. ‚Mastoidis’). Photosynthetic rate as well as stomatal conductance were decreased in stressed plants. Osmotic potential (π) declined rapidly in stressed plants indicating their ability for osmoregulation. Bulk modulus of elasticity (ε) was significantly higher in stressed compared to well irrigated plants. The volume fraction of intercellular spaces of the upper palisade parenchyma, the spongy parenchyma as well as the lower palisade parenchyma were significantly lower in stressed compared to well irrigated plants. On the other hand, the density of mesophyll cells in the upper palisade parenchyma, spongy parenchyma and lower palisade parenchyma increased significantly in stressed plants

EFFECTS OF HERBICIDES ON CARBON DIOXIDE UPTAKE BY PINE SEEDLINGS

1967 ◽  
Vol 45 (7) ◽  
pp. 961-971 ◽  
Author(s):  
S. Sasaki ◽  
T. T. Kozlowski
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Soil Surface ◽  
Pinus Resinosa ◽  
Spray Application ◽  
Leaf Color ◽  
Carbon Dioxide Uptake ◽  
Chlorophyll Breakdown ◽  
Pine Seedlings ◽  
Steady Rate

Experiments were conducted on effects of herbicides applied to soil or sprayed on shoots on CO2 uptake of 3-year-old Pinus resinosa Ait. seedlings. When applied to the soil, atrazine, monuron, EPTC, and 2,4-D at 20 lb/ac (soil surface basis) or at 4000 p.p.m. variously decreased absorption of CO2. Monuron checked gas exchange most rapidly, with no CO2 uptake measurable after 10 days. Atrazine and 2,4-D inhibited absorption of CO2 at a steady rate. EPTC caused a delayed inhibition of CO2 uptake. DCPA, CDAA, CDEC, and NPA did not affect gas exchange significantly. Monuron applied as a spray depressed CO2 uptake somewhat faster than the soil-applied herbicide. Very rapid inhibition of CO2 uptake was observed after spray application of 2,4-D or EPTC. Atrazine affected gas exchange similarly when applied as a spray or incorporated in the soil. DCPA, applied as a spray, did not affect absorption of CO2 significantly. Possible reasons for differences in CO2 uptake after spray and soil-application of certain herbicides are discussed. Inert ingredients of EPTC applied as sprays at a concentration of 4000 p.p.m. greatly reduced CO2 absorption 3 days after treatment. However, the rapid early depression of gas exchange was followed by recovery, with no obvious deleterious effects on growth up to 3 months after treatment. Some herbicides checked CO2 absorption without chlorophyll breakdown whereas others did not. Monuron completely inhibited CO2 uptake long before any changes in leaf color were evident. In contrast, depression of CO2 absorption by atrazine and 2,4-D rather closely paralleled development of toxicity symptoms, especially chlorosis. These observations suggested that some herbicides such as monuron affected the photosynthetic mechanism more directly than others such as atrazine, 2,4-D, and EPTC.

Association of malva vein-clearing virus and rhabdoviruslike particles with mottle and vein clearing of malva plants

1986 ◽  
Vol 64 (1) ◽  
pp. 85-89 ◽  
Author(s):  
Maria-Ivone C. Henriques ◽  
Fernando S. Henriques
Keyword(s):  
Inclusion Bodies ◽  
Inner Core ◽  
Dense Body ◽  
Mesophyll Cells ◽  
Cytoplasmic Inclusions ◽  
Thin Sections ◽  
Phloem Parenchyma ◽  
Vein Clearing ◽  
Perinuclear Space ◽  
Parenchyma Cells

Thin sections of malva (Malva sp.) leaves collected in the field and showing mottle and vein-clearing symptoms were examined by electron microscopy. Cytoplasmic inclusions typical of potyvirus and consisting of pinwheels, laminated aggregates, and scrolls were readily observed. In addition, rhabdoviruslike particles were also seen in the perinuclear space of phloem parenchyma cells and within membranous sacs scattered throughout the cytoplasm of other vascular bundle cells. Occasionally rhabdoparticles could be found embedded in an amorphous electron-dense body located within the cell vacuole. The rhabdovirus particles, approximately 75 × 300 nm, were bound by a membrane with outer projections and had an inner core displaying cross striations. The cytoplasm of infected mesophyll cells had chloroplasts containing large amorphous inclusion bodies and had extensive membranous tubules that were frequently associated with the potyvirus inclusions. These ultrastructural aspects, the size of the particles, and the data on host range indicate that malva plants under study were doubly infected by viruses which were tentatively identified as malva vein-clearing virus and a previously undescribed rhabdovirus.

Effect of Picloram on Organogenesis in Detached Leaves ofEcheveria elegansBgr.

Weed Science ◽  
1976 ◽  
Vol 24 (2) ◽  
pp. 175-182 ◽  
Author(s):  
M. V. S. Raju ◽  
R. Grover
Keyword(s):  
Root Elongation ◽  
Shoot Organogenesis ◽  
Tracheary Elements ◽  
Vascular Differentiation ◽  
Root Primordia ◽  
Low Concentrations ◽  
Parenchyma Cells ◽  
Callus Production ◽  
Detached Leaves ◽  
Apical Organization

The effect of picloram (4-amino-3,5,6-trichloropicolinic acid) on regeneration of detached leaves ofEcheveria elegansBgr. was studied. Picloram stimulated callus production at all concentrations. Low concentrations of 1 to 15 ppmw picloram did not affect shoot organogenesis and the same, however, stimulated rhizogenesis. Inhibition of both root- and shoot-organogenesis was noticeable at concentrations below 20 ppmw and above. Roots increased in number at all picloram concentrations below 40 ppmw, the maximum number being at concentration of 15 to 20 ppmw of the herbicide. Observations indicated that root elongation was considerably suppressed. Picloram-induced callus contained mature parenchyma cells devoid of contents and considerable amount of tissue disruption was noticed. Irregular vascular differentiation and obliteration of tissues particularly in the region of tracheary elements, were obvious. Although normal apical organization was lacking in root primordia and in arrested short roots, these elongated normally into mature roots when they were transferred to water, thus indicating that apical meristems were not severely affected by picloram.

Development of infection structures by Hemileia vastatrix in resistant and susceptible selections of Coffea and in Phaseolus vulgaris

1993 ◽  
Vol 71 (8) ◽  
pp. 1001-1008 ◽  
Author(s):  
T. A. Coutinho ◽  
F. H. J. Rijkenberg ◽  
M. A. J. van Asch
Keyword(s):  
Phaseolus Vulgaris ◽  
Primary Infection ◽  
Intercellular Spaces ◽  
Hemileia Vastatrix ◽  
Mesophyll Cells ◽  
Sequence Of Events ◽  
Successful Infection ◽  
Coffee Leaf Rust ◽  
Subsidiary Cells ◽  
Mother Cells

The sequence of events leading to successful infection of Coffea by Hemileia vastatrix, following the formation of an appressorium over a stoma, was investigated using scanning electron microscopy. In the host, Coffea arabica, a torpedoshaped substomatal vesicle initial develops bilaterally from the apex of the infection wedge, while in the nonhost, Phaseolus vulgaris, the infection wedge protrudes into the substomatal chamber. The substomatal vesicle in both host and nonhost, at 48 h postinoculation, is anchor shaped. Haustorial mother cells are formed on stubby primary infection hyphae that curve back onto subsidiary cells. No differences in appearance of these structures were noted between resistant and susceptible coffee selections. A much-branched mycelium ramifies through the intercellular spaces of the mesophyll cells 96 h postinoculation in the host. In bean, the SSV began to collapse 48 h postinoculation. Key words: coffee leaf rust, infection, penetration, Coffea, appressorium, substomatal vesicle.

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