ACCLIMATION OF PHOTOSYNTHESIS AND GROWTH OF BANANA (MUSA SP.) TO NATURAL SHADE IN THE HUMID TROPICS

2008 ◽  
Vol 44 (3) ◽  
pp. 301-312 ◽  
Author(s):  
A. M. W. K. SENEVIRATHNA ◽  
C. M. STIRLING ◽  
V. H. L. RODRIGO

SUMMARYGrowth and photosynthetic performance of banana (Musa sp.) grown in three levels of natural shade (33, 55 and 77% reduction in incoming radiation) were compared to an unshaded control treatment. Net CO2 assimilation rates generally decreased with increasing shade. Chlorophyll fluorescence revealed short-term dynamic photoinhibition under high light conditions but no evidence of sustained photoinhibitory damage to photosystem II. Dynamic photoinhibition decreased with increasing shade, with the greatest depression in the variable to maximal fluorescence ratio (Fv/Fm) occurring in unshaded plants during the middle of the day. Specific leaf area and leaf area ratio increased proportionately with increasing shade, whilst the chlorophyll a/b ratio decreased, reflecting a greater efficiency of light utilization under shady conditions. The optimum shade level for photosynthetic productivity would be one at which the level of photosynthetic photon flux density (PPFD) is high enough to saturate CO2 assimilation but low enough to induce shade acclimation and to reduce photoinhibition. Under the conditions studied here, the saturation level of PPFD was around 1000 μmol m−2 s−1, a light level typical of the tree-based intercropping systems in which banana is commonly grown in the tropics.

Weed Science ◽  
1988 ◽  
Vol 36 (6) ◽  
pp. 779-783 ◽  
Author(s):  
Armando A. Dall'Armellina ◽  
Robert L. Zimdahl

Field bindweed and Russian knapweed were grown from seed or rhizome segments under 520, 325, or 236 μmol·m–2· s–1photosynthetic photon flux density (PPFD) to determine vegetative and reproductive response. Flower production in both species declined with decreasing light level. Leaf area of field bindweed decreased as light level decreased, but Russian knapweed leaf area increased as light intensity decreased from 520 to 325 μmol·m–2·s–1PPFD or from 520 to 236 μmol·m–2·s–1. Dry matter of shoots, roots, and rhizomes of field bindweed grown from seed declined as light level decreased, but the only response of plants grown from rhizome segments was complete inhibition of rhizome production. Dry matter of Russian knapweed shoots and roots in plants grown from seed or rhizome segments decreased as light decreased. In both species the total PPFD was more important than whether low or high light level occurred first.


1988 ◽  
Vol 39 (5) ◽  
pp. 863 ◽  
Author(s):  
M Zeroni ◽  
J Gale

Rose plants (Rosa hybrida cv. Sonia, Syn. Sweet Promise) were placed in growth chambers under conditions resembling winter in a controlled environment greenhouse in the desert: mild temperatures, high incident photosynthetic photon flux density (PPFD), high air humidity and 10.5 h daylenght. Concentrations of CO2 in the air were maintained throughout the day at 320, 600 or 1200 8l l-1 with approximately 350 8l l-1 at night. Plant growth (length, fresh and gry weight), development (breaks, blindness), flower yield and flower quality (flower bud diameter, fresh weight and cane length) indices were monitored throughout three consecutive flowering cycles. CO2 supplementation caused an increase in leaf resistance to water vapour diffusion, accompanied by a reduction in the rate of transpiration per unit leaf area, Total leaf area increased at higher CO2 concentrations. Water use per plant did not change. Plant water potentials increased with rising CO2 concentrations. Growth, development, flower yield and flower quality were greatly enahnced in the CO2-enriched atmosphere. The response of growth and development to CO2 supplementation tended to decrease slightly with time when calculated per branch, but increased when calculated per plant. Flower yield and qualtiy did not change with time. The highest CO2 treatment resulted in a sustained, approximately 50% increase in yield, and doubling of the above quality indices throughout the three growth cycles.


Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1002 ◽  
Author(s):  
Ivan Paucek ◽  
Giuseppina Pennisi ◽  
Alessandro Pistillo ◽  
Elisa Appolloni ◽  
Andrea Crepaldi ◽  
...  

In Northern Europe, the use of light–emitting diodes (LEDs) is widely adopted in protected horticulture, enabling to enhance plant growth by ensuring needed radiative fluxes throughout seasons. Contrarily, the use of artificial lighting in Mediterranean greenhouse still finds limited applications. In this study, the effects of supplemental LED interlighting on vegetative development, fruit growth, yield, and fruit quality of high-wire tomato plants (Solanum lycopersicum L. cv. ‘Siranzo’) during spring and summer season were addressed in a hydroponic greenhouse in Italy. Plants were either grown under natural solar radiation (control), or by adding supplemental LED interlighting. LED treatment featured red (R) and blue (B) light (RB ratio of 3) and a photosynthetic photon flux density of 170 µmol m−2 s−1 for 16 h d−1. Supplemental LED interlighting enhanced yield as a result of increased fruit weight and dimension. While no effects on soluble solids content and fruit color at harvesting were observed, supplemental LED interlighting accelerated ripening by one week in spring and two weeks in summer and this also resulted in increased cumulated productivity (+16%) as compared to control treatment. Overall, supplemental LED interlighting can represent a feasible technology for tomato greenhouse production also in the Mediterranean region.


Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 397 ◽  
Author(s):  
Virupax C. Baligar ◽  
Marshall K. Elson ◽  
Alex-Alan F. Almeida ◽  
Quintino R. de Araujo ◽  
Dario Ahnert ◽  
...  

Cacao (Theobroma cacao L.) was grown as an understory tree in agroforestry systems where it received inadequate to adequate levels of photosynthetic photon flux density (PPFD). As atmospheric carbon dioxide steadily increased, it was unclear what impact this would have on cacao growth and development at low PPFD. This research evaluated the effects of ambient and elevated levels carbon dioxide under inadequate to adequate levels of PPFD on growth, physiological and nutrient use efficiency traits of seven genetically contrasting juvenile cacao genotypes. Growth parameters (total and root dry weight, root length, stem height, leaf area, relative growth rate and net assimilation rates increased, and specific leaf area decreased significantly in response to increasing carbon dioxide and PPFD. Increasing carbon dioxide and PPFD levels significantly increased net photosynthesis and water-use efficiency traits but significantly reduced stomatal conductance and transpiration. With few exceptions, increasing carbon dioxide and PPFD reduced macro–micro nutrient concentrations but increased uptake, influx, transport and nutrient use efficiency in all cacao genotypes. Irrespective of levels of carbon dioxide and PPFD, intraspecific differences were observed for growth, physiology and nutrient use efficiency of cacao genotypes.


2018 ◽  
Vol 35 (0) ◽  
Author(s):  
D.R.O. SILVA ◽  
L. VARGAS ◽  
D. AGOSTINETTO ◽  
F.M. SANTOS

ABSTRACT: Herbicide resistance can confer lower competitive abilities; however scarse information is available about the photosynthetic performance between glyphosate-resistant and -susceptible hairy fleabane biotypes coming from areas with similar weed management history. Thus, the goal was to evaluate the photosynthetic performance under different light intensities between glyphosate-resistant and -susceptible hairy fleabane biotypes, from RR soybean fields with a similar weed management history. The tested factors were glyphosate resistant and susceptible biotypes and 12 levels of photosynthetic photon flux density. Plants were cultivated in plastic cups, and at the stage of 10-12 leaves they were subjected to treatments with artificial lighting systems. The net photosynthetic rate, stomatal conductance, substomatal CO2 concentration, transpiration rate, instantaneous water use efficiency, light compensation point and quantum yield were evaluated. In all the evaluated photosynthetic parameters, biotype R showed superior characteristics compared to susceptible biotypes, with the exception of the transpiration rate, where there were no differences. The differences between biotypes may not be associated to glyphosate resistance or susceptibility, but to the evolutionary characteristics of the biotypes.


Author(s):  
Aistė Bagdonavičienė ◽  
Aušra Brazaitytė ◽  
Julė Jankauskienė ◽  
Pavelas Duchovskis

The objective of our studies was to evaluate the assimilative indices of cucumber (‘Pasalimo F1’) and tomato (‘Marissa F1’) transplants, cultivated under various photosynthetic photon flux densities (PPFD) were provided by light-emitting diodes (LEDs). Experiment was performed in phytotron complex of Institute of Horticulture, LRCAF. A system of high-power, solid-state lighting modules with 92 % 638 nm (red) + 665 nm (red) + 731 nm (far red) and 8 % 447 nm (blue) was used in the experiments. The generated PPFD of each type of five solid-state modules was ~200 and ~400 μmol m-2 s-1. Our experiment revealed that increased net assimilation rate (NAR) depended on increased PPFD of cucumber and tomato hybrid. 400 μmol m-2 s-1 LED illumination had positive effect on relative growth rate (RGR). Cucumbers which were grown under 200 μmol m-2 s-1 had bigger leaf area ratio (LAR) and specific leaf area (SLA), their development has been bigger as compared to higher 400 μmol m-2 s-1 PPFD. High PPFD LED illumination had positive effect on leaf weight ratio (LWR), shoot root ratio (SRR) and tomato transplants development. These studies with various photosynthetic photon flux densities (PPFD) and LEDs light should be continued throughout plant vegetation.


Weed Science ◽  
1991 ◽  
Vol 39 (4) ◽  
pp. 590-594 ◽  
Author(s):  
Robert L. Zimdahl ◽  
Jingzhu Lin ◽  
Armando A. Dall'Armellina

Greenhouse and field experiments were conducted to determine effects of light, water, and chlorsulfuron on growth of Canada thistle. In the greenhouse, shoot and root dry weight, leaf area, and number of inflorescences decreased as light and water levels decreased. In the field, shoot and root dry weight, leaf area, and number of Canada thistle inflorescences were positively correlated with light intensity from 1832 to 30 μmol m−2s−1photosynthetic photon flux density (PPFD). The greatest effect of light was on inflorescence production which was eliminated at 30 μmol m−2s−1(PPFD). The combined effect of water stress and chlorsulfuron decreased root and shoot growth but did not eliminate it.


Weed Science ◽  
1990 ◽  
Vol 38 (4-5) ◽  
pp. 351-357 ◽  
Author(s):  
David T. Patterson

Spurred anoda and velvetleaf were grown for 40 days in controlled-environment chambers in monocultures at densities of 2, 4, 8, and 12 plants per 20-cm-diam pot and in mixed culture with all combinations of 2, 4, 8, and 12 plants of each species per pot. The day/night temperature was 29/23 C, and the photosynthetic photon flux density (PPFD) was 1000 μE m–2s–1. Shoot dry weights and leaf areas of the two species were similar when they were grown in monoculture. However, in mixed culture spurred anoda exceeded velvetleaf in leaf area/plant and shoot weight/plant in 15 out of 16 treatments. Multiple linear regression equations relating shoot biomass/plant to the density of both species in mixed culture were calculated. Comparison of competition coefficients from these equations indicated that the competitive impact of a single spurred anoda plant was equivalent to the impact of 2.5 velvetleaf plants. In mixed culture, spurred anoda always contributed a greater proportion of the total shoot weight and total leaf area per pot than would be predicted from its proportion of the total plant population. These results indicate spurred anoda is competitively superior to velvetleaf.


1988 ◽  
Vol 68 (4) ◽  
pp. 1209-1218 ◽  
Author(s):  
ATHANASIOS P. PAPADOPOULOS ◽  
DOUGLAS P. ORMROD

The effect of four equidistant spacings (23, 30, 38, 45 cm) applied to four-row plantings of greenhouse tomato (Lycopersicon esculentum Mill. ’CR-6’) on plant net photosynthesis (P) and transpiration (E) was studied. Closer spacing decreased the leaf-area-based net photosynthesis (Pa) of the lower leaves but had little effect on the Pa of the upper leaves. The exposed parts of a tomato plant could adjust their Pa rates upwards to compensate for the low Pa of their shaded parts. The leaf-weight-based net photosynthesis (Pw) increased with the decrease of plant spacing and it was higher in inside compared to outside plants. The differences between the Pa and Pw results were mostly attributable to the effect of light in increasing the specific leaf weight (SLW). The E rate of plants increased at the closest spacing and there was a higher leaf weight based transpiration (Ew) in inside than outside plants. The leaf area based transpiration (Ea) and stomatal resistance (Rw) were not affected appreciably by light (photosynthetic photon flux density) other than at very low levels (i.e. less than 100 μmol m−2 s−1) where there was a sharp increase in Rw and a corresponding decrease in Ea. The P of plants growing in an environment of gradually declining duration and intensity of solar irradiance declined with the aging of plants. There was no similar effect on E.Key words: Lycopersicon esculentum Mill, plant spacing, photosynthesis, transpiration, tomato


HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1037B-1037
Author(s):  
Harry G. Simmons ◽  
Alisara Menakanit ◽  
Surawit Wannakrairoj ◽  
Poonpipope Kasemsap

Bamboo has increasingly become a popular exterior ornamental plant because of its durability, versatility, and evergreen qualities in conditions of extreme temperature and moisture variations. Use as an interior foliage plant has been limited due to the difficulty of finding species adaptable to lower light levels. Nineteen species from seven genera (Bambusa, Cephalostachyum, Dendrocalamus, Gigantochloa, Schizostachyum, Thyrsostachys, and Vietnamosasa) were evaluated. Fifteen plants from each species were potted in like conditions (50% leaf mold; 50% topsoil; 5 g of 14–14–14 controlled-release fertilizer) and grown under a maximum daily photosynthetic photon flux density (PPFD) range between 1200 to 2000 μmol·m-2·s-1 for 6 weeks. Chlorophyll content of leaves was measured. The commercial quality of leaves, culms, and general appearance was also recorded. Light was then limited to a maximum PPFD of 150 to 300 μmol m-2s-1 for 6 weeks and all measurements were again recorded. Five species had significant increases in chlorophyll content after the 6-week period of reduced light levels. Species with a larger maturity size had a greater mortality percentage as well as lower quality leaf and overall appearance when grown under reduced light levels. Culm quality remained constant in 18 of the 19 species after the 6-week period. Vietnamosasa ciliata showed the greatest increase in chlorophyll levels as well as highest commercial quality of leaf and overall appearance.


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