Effect of Atrazine and Mesotrione on Centipedegrass Growth, Photochemical Efficiency, and Establishment

2009 ◽  
Vol 23 (1) ◽  
pp. 67-72 ◽  
Author(s):  
J. Scott McElroy ◽  
Robert H. Walker
Keyword(s):  
Photosystem Ii ◽  
Maximum Rate ◽  
Photochemical Efficiency ◽  
Ground Cover ◽  
Rate Range ◽  
Photosystem Ii Efficiency ◽  
Greenhouse Trial ◽  
Time Period

Centipedegrass is tolerant of both atrazine and mesotrione when applied separately to established turf. However, no information is available regarding the use of mesotrione or the synergistic mixture of atrazine plus mesotrione applied to centipedegrass during seeded establishment. Research was conducted to evaluate centipedegrass tolerance to various rates and combinations of atrazine plus mesotrione when applied 14 d after emergence (DAE). Experiment 1 evaluated centipedegrass tolerance to atrazine and mesotrione in a broad rate-range screen in a greenhouse environment. Variations were observed between greenhouse trial runs with respect to injury and biomass with less injury and decrease in biomass observed in run 2. Overall, atrazine alone and atrazine plus mesotrione were more injurious for a greater time period and decreased biomass more than mesotrione alone. In fact, although mesotrione alone initially reduced centipedegrass photosystem II efficiency, an overall increase in efficiency was observed 28 d after treatment (DAT). Based on experiment 1, atrazine at 0.28 kg ai/ha was the maximum rate that could be applied to seedling centipedegrass when tank mixed with mesotrione. Experiment 2 evaluated atrazine at 0.28 kg/ha plus mesotrione at 0.03 to 0.28 kg/ha on centipedegrass field establishment. Although all atrazine plus mesotrione treatments reduced centipedegrass ground cover 28 DAT; no treatment reduced centipedegrass ground cover 49 DAT.

scholarly journals Shading Reduces Water Deficit in Strawberry (Fragaria × ananassa Duch.) Plants during Vegetative Growth

2021 ◽  
Author(s):  
Henry A. Cordoba-Novoa ◽  
María Mercedez Pérez Trujillo ◽  
Brahyam Emmanuel Cruz Rincon ◽  
Nixon Florez Velazco ◽  
Stanislav Magnitskiy ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Light Intensity ◽  
Water Potential ◽  
Net Photosynthetic Rate ◽  
Water Deficit ◽  
Photosynthetic Rate ◽  
Vegetative Growth ◽  
Incident Light ◽  
Photochemical Efficiency ◽  
Photosystem Ii Efficiency

Strawberry (Fragaria × ananassa Duch.) is a commercially important crop with high water requirements, for which it is necessary to find strategies that mitigate the influence of water deficit on plant growth. This study was aimed to evaluate the effects of shading on the vegetative growth of strawberry cv. Sweet Ann under water deficit. The treatments consisted of the combination of two levels of shading (light intensity reduced on 47% vs. non-shaded plants) and two levels of water availability (water deficit vs. well-watered plants). The water deficit reduced the leaf water potential from -1.52 to -2.21 MPa, and diminished stomatal conductance, net photosynthetic rate (from 9.13 to 2.5 μmol m-2 s-1), photosystem II photochemical efficiency (from 0.79 to 0.67), and biomass accumulation, while increased the electrolyte leakage. The shading allowed the water-deficient plants to maintain water potential (-1.58 MPa) and photosystem II efficiency (0.79) and to increase water use efficiency (from 14.80 to 86.90 μmol CO2/mmol H2O), net photosynthetic rate (from 2.40 to 9.40 μmol m-2 s-1) and biomass of leaves, crowns, and roots compared to non-shaded plants without water limitation. These results suggest that a reduction in incident light intensity attenuates the effects of stomatic and non-stomatic limitations caused by water deficit during vegetative growth of strawberry.

scholarly journals Biomass accumulation, photochemical efficiency of photosystem II, nutrient contents and nitrate reductase activity in young rosewood plants (Aniba rosaeodora Ducke) submitted to different NO3-:NH4+ ratios

2007 ◽  
Vol 37 (4) ◽  
pp. 533-541 ◽  
Author(s):  
Denize Caranhas de Sousa Barreto ◽  
José Francisco de Carvalho Gonçalves ◽  
Ulysses Moreira dos Santos Júnior ◽  
Andreia Varmes Fernandes ◽  
Adriana Bariani ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Nitrate Reductase ◽  
Growth Performance ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Photochemical Efficiency ◽  
Biomass Accumulation ◽  
Nitrate Content ◽  
Chl A ◽  
Culture Substrate

The rosewood (Aniba rosaeodora Ducke) is a native tree species of Amazon rainforest growing naturally in acidic forest soils with reduced redox potential. However, this species can also been found growing in forest gaps containing oxide soils. Variations in the forms of mineral nitrogen (NO3- or NH4+) may be predicted in these different edaphic conditions. Considering that possibility, an experiment was carried out to analyze the effects of different NO3-:NH4+ ratios on the growth performance, mineral composition, chloroplastid pigment contents, photochemical efficiency photosystem II (PSII), and nitrate redutase activity (RN, E.C.1.6.6.1) on A. rosaeodora seedlings. Nine-month-old seedlings were grown in pots with a washed sand capacity of 7.5 kg and submitted to different NO3-:NH4+ ratios (T1 = 0:100%, T2 = 25:75%, T3 = 50:50%, T4 = 75:25%, and T5 = 100:0%). The lowest relative growth rate was observed when the NO3-:NH4+ ratio was equal to 0:100%. In general, high concentrations of NO3- rather than NH4+ favored a greater nutrient accumulation in different parts of the plant. For the chloroplastid pigment, the highest Chl a, Chl b, Chl tot, Chl a/b and Chl tot/Cx+c contents were found in the treatment with 75:25% of NO3-:NH4+, and for Chl b and Cx+c it was observed no difference. In addition, there was a higher photochemical efficiency of PSII (Fv/Fm) when high NO3- concentrations were used. A linear and positive response for the nitrate reductase activity was recorded when the nitrate content increased on the culture substrate. Our results suggest that A. rosaeodora seedlings have a better growth performance when the NO3- concentrations in the culture substrate were higher than the NH4+ concentrations.

scholarly journals Response of common buckwheat and Tartary buckwheat from different elevations to selenium treatment

Fagopyrum ◽  
2021 ◽  
Vol 38 (1) ◽  
pp. 15-23
Author(s):  
Aleksandra Golob ◽  
Neja Luzar ◽  
Mateja Germ
Keyword(s):  
Photosystem Ii ◽  
Photochemical Efficiency ◽  
Morphological Characteristics ◽  
Tartary Buckwheat ◽  
Control Group ◽  
Common Buckwheat ◽  
Biochemical Characteristics ◽  
Selenium Treatment ◽  
Uv Absorbing Compounds ◽  
Effective Photochemical Efficiency

Common buckwheat and Tartary buckwheat were grown in Slovenia outdoors at different elevations – 300 m, 600 m and 1180 m a.s.l. Both species were foliarly treated with selenium twice (in the vegetative phase and in the flowering phase). The effects of Se treatment and different growing locations on selected biochemical, physiological and anatomical traits were monitored. In Se treated common buckwheat, amount of chlorophylls was higher in plants from Ljubljana (the lowest elevation – 300 m a.s.l.) than in plants grown in Podbeže (600 m a.s.l.), whereas in control group, plants grown in Ljubljana contained more chlorophylls than plants from Javorje (the highest elevation – 1180 m a.s.l.). In both buckwheat species, Se alone did not affect amount of chlorophylls in any of location. In Se treated common buckwheat plants, the amount of UV absorbing compounds was the highest in plants, grown at the highest elevation. In common buckwheat, Se lowered the number of CaOx in plants, grown in Javorje. Conditions at different elevations, as well as treatments with Se, did not affect potential and effective photochemical efficiency of Photosystem II. Keywords: common buckwheat, Tartary buckwheat, elevation, selenium, morphological characteristics, biochemical characteristics

Light response of D1 turnover and photosystem II efficiency in the seagrassZostera capricorni

Planta ◽  
1996 ◽  
Vol 198 (3) ◽  
pp. 319-323 ◽  
Author(s):  
Yvette S. Flanigan ◽  
Christa Critchley
Keyword(s):  
Photosystem Ii ◽  
Light Response ◽  
Photosystem Ii Efficiency ◽  
D1 Turnover

Reduction in photosystem II efficiency during a virus-controlled Emiliania huxleyi bloom

2014 ◽  
Vol 495 ◽  
pp. 65-76 ◽  
Author(s):  
SA Kimmance ◽  
MJ Allen ◽  
A Pagarete ◽  
J Martínez Martínez ◽  
WH Wilson
Keyword(s):  
Photosystem Ii ◽  
Emiliania Huxleyi ◽  
Photosystem Ii Efficiency

Photosynthesis, quenching of chlorophyll fluorescence and thermal energy dissipation in iron-deficient sugar beet leaves

1998 ◽  
Vol 25 (4) ◽  
pp. 403 ◽  
Author(s):  
Fermín Morales ◽  
Anunciación Abadía ◽  
Javier Abadía
Keyword(s):  
Energy Dissipation ◽  
Iron Deficiency ◽  
Photosystem Ii ◽  
Sugar Beet ◽  
Electron Flow ◽  
Reaction Centers ◽  
O2 Evolution ◽  
Photosystem Ii Efficiency ◽  
Iron Deficient ◽  
Additional Support

In sugar beet (Beta vulgaris L.) iron deficiency decreased not only the photosynthetic rate but also the actual photosystem II efficiency at steady-state photosynthesis. In moderate iron deficiency, the decrease in actual photosystem II efficiency under illumination was related to closure of photosystem II reaction centers, whereas in severe iron deficiency it was associated to decreases of intrinsic photosystem II efficiency. The O2 evolution, on an absorbed light basis, decreased more than the actual photosystem II efficiency, suggesting the presence of a significant fraction of electron transport to molecular oxygen or the existence of some form of cyclic electron flow. Iron-deficient leaves reduced the excess of light absorbed that cannot be used in photosynthesis not only by decreasing absorptance, but also by dissipating a large part of the light absorbed by the photosystem II antenna. This mechanism, that protects the photosystem II reaction centers through the enhancement of energy dissipation, was related to the de-epoxidation of violaxanthin (V) to antheraxanthin (A) and zeaxanthin (Z) in iron-deficient leaves. These data provide additional support for a role of Z+A in photoprotection under conditions of excess photosynthetic light absorption.

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