The influence of the hemiparasitic angiosperm Cassytha pubescens on photosynthesis of its host Cytisus scoparius

Infection with Cassytha pubescens R.Br, an Australian native hemiparasitic plant, can lead to death of the invasive shrub, Cytisus scoparius L. Link (Scotch broom). We examined the influence of C. pubescens on photosynthetic physiology of C. scoparius to determine whether this might contribute to death of infected plants. Infected C. scoparius had significantly lower photosynthetic rates, stomatal conductance and transpiration, and higher Ci (internal [CO2]), than uninfected plants. Rapid light response curves, determined using chlorophyll fluorescence, indicated significantly lower light-saturated electron transport rates and lower quantum yields for infected plants relative to uninfected plants. However, Rubisco content did not differ between infected and uninfected plants, suggesting the lower photosynthetic rates were most likely due to stomatal closure, rather than lower photosynthetic capacity. As a consequence of lower assimilation rates, PSII efficiency was lower in infected plants than uninfected plants across the diurnal cycle. Infected plants also had significantly lower pre-dawn Fv/Fm values and slower recovery from exposure to high light than uninfected plants. Our results suggest that infected C. scoparius are more susceptible to photodamage than uninfected plants. Combined with lower carbon fixation rates, this could contribute to the poor performance and even death of infected plants.

Download Full-text

Drought Enhances Stomatal Closure in Response to Shading in Sorghum (Sorghum bicolor) and in Millet (Pennisetum americanum)

Functional Plant Biology ◽

10.1071/pp9950001 ◽

1995 ◽

Vol 22 (1) ◽

pp. 1 ◽

Cited By ~ 5

Author(s):

HG Jones ◽

DO Hall ◽

JE Corlett ◽

A Massacci

Keyword(s):

Sorghum Bicolor ◽

Water Status ◽

Stomatal Closure ◽

Light Response ◽

Pennisetum Americanum ◽

Crop Water ◽

Response Curves ◽

Early Stages ◽

Light Response Curves ◽

Sorghum Bicolor L

When field-grown sorghum (Sorghum bicolor (L.) Moench) and millet (Pennisetum americanum (L.) Leeke) plants are subjected to drought, the speed of stomatal closure in response to darkness is enhanced in comparison with the speed observed in well-irrigated control plants. This shade-induced closure is most apparent at early stages of desiccation and is not rapidly reversible. These results need to be considered when developing protocols for the measurement of photosynthetic light response curves in the field. The sensitivity to crop water status of this stomatal closure response potentially provides a very valuable means for detection of the early stages of soil drying, and may also provide opportunities for screening different varieties for their adaptation to drought conditions.

Download Full-text

Comparative Net Photosynthesis of Four Hevea brasiliensis Clonal Seedlings

Experimental Agriculture ◽

10.1017/s0014479700008978 ◽

1978 ◽

Vol 14 (4) ◽

pp. 337-340 ◽

Cited By ~ 9

Author(s):

Zahar Samsuddin ◽

Ivan Impens

Keyword(s):

Hevea Brasiliensis ◽

Light Response ◽

Net Photosynthesis ◽

Response Curves ◽

Photosynthetic Rates ◽

Light Response Curves ◽

Single Leaf

SUMMARYSingle-leaf net photosynthesis versus light response curves of four Hevea brasiliensis clonal seedlings showed that it was possible to divide photosynthetic rates into high and low classes.

Download Full-text

Photosynthetic Rate, Flowering, and Yield Component Alteration in Hazelnut in Response to Different Light Environments

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.121.6.1103 ◽

1996 ◽

Vol 121 (6) ◽

pp. 1103-1111 ◽

Cited By ~ 22

Author(s):

Cheryl R. Hampson ◽

Anita N. Azarenko ◽

John R. Potter

Keyword(s):

Photosynthetic Rate ◽

Dark Respiration ◽

Stomatal Density ◽

Chlorophyll Concentration ◽

Light Response ◽

Dry Weight ◽

Yield Component ◽

Response Curves ◽

Photosynthetic Rates ◽

Light Response Curves

In hazelnut (Corylus avellana L.), vigorous vegetative growth and traditional orchard practices that include little or no pruning combine to produce a dense, shady canopy. A study designed to quantify the effect of shade on reproduction and photosynthetic rate in this shade-tolerant species was undertaken to assess whether some degree of pruning might improve productivity. Shade cloth was used to exclude 30%, 47%, 63%, 73%, or 92% of ambient sunlight from whole `Ennis' and `Barcelona' trees from mid-May until harvest. Photosynthetic light response curves were obtained for leaves that had developed in full sunlight, deep inside the canopy of unshaded trees, or in 92% shade. Light-saturated net photosynthetic rates were 12.0, 6.1, and 9.3 μmol·m-2·s-1 of CO2 and dark respiration rates were 2.0, 1.1, and 0.7 μmol·m-2·s-1 of CO2, respectively, for the three light regimes. Light-saturated photosynthetic rates of leaves from 30% or 63% shade differed little from the control (0% shade). Area per leaf increased by 49% and chlorophyll concentration (dry weight basis) by 157% as shading increased from 0% to 92%. Shading to 92% reduced specific leaf weight (68%), stomatal density (30%), light compensation point (69%), and dark respiration rate (63%) compared to controls. Female inflorescence density declined by about one-third and male inflorescence density by 64% to 74% in the most heavily shaded trees of both cultivars compared to controls. Shade was more detrimental to yield than flowering: yield per tree dropped by >80%, from 2.9 to 3.4 kg in full sun to 0.6 to 0.9 kg in 92% shade. Shade reduced yield primarily by decreasing nut number and secondarily by decreasing nut size. The incidence of several kernel defects increased as shade increased. Therefore, hazelnut leaves showed considerable capacity to adapt structurally and functionally to shade, but improving light penetration into the canopy would probably increase orchard productivity.

Download Full-text

Growth, Carbon Acquisition, and Source-Sink Relationships in `Titan' Red Raspberry

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.119.6.1163 ◽

1994 ◽

Vol 119 (6) ◽

pp. 1163-1168 ◽

Cited By ~ 14

Author(s):

Gina E. Fernandez ◽

Marvin P. Pritts

Keyword(s):

Accumulation Rate ◽

Light Response ◽

Dry Weight ◽

Rubus Idaeus ◽

Field Conditions ◽

Partial Recovery ◽

Red Raspberry ◽

Response Curves ◽

Photosynthetic Rates ◽

Light Response Curves

Seasonal changes in growth, mean maximal photosynthetic rates, and the temperature and light response curves of `Titan' red raspberry (Rubus idaeus L.) were obtained from potted plants grown under field conditions. Primocane dry weight accumulation increased steadily at the beginning and the end of the season, but growth slowed midseason during fruiting. The slower midseason dry-weight accumulation rate coincided with an increase in root dry weight. Primocane net assimilation rate (NAR) was highest early in the season. Floricane photosynthetic rates (A) were highest during the fruiting period, while primocane A remained steady throughout the season. Primocane and floricane leaflets displayed a midday depression in A under field conditions, with a partial recovery in the late afternoon. Photosynthetic rates of primocane and floricane leaves were very sensitive to temperature, exhibiting a decline from 15 to 40C. Light-response curves differed depending on cane type and time of year. A temporal convergence of sink demand from fruit, primocanes, and roots occurs when plants experience high temperatures. These factors may account for low red raspberry yield.

Download Full-text

Physiological ecology of lodgepole pine (Pinuscontorta) in an enriched CO2 environment

Canadian Journal of Forest Research ◽

10.1139/x85-067 ◽

1985 ◽

Vol 15 (2) ◽

pp. 417-421 ◽

Cited By ~ 28

Author(s):

K. O. Higginbotham ◽

J. M. Mayo ◽

S. L'Hirondelle ◽

D. K. Krystofiak

Keyword(s):

Surface Area ◽

Leaf Surface ◽

Lodgepole Pine ◽

Stomatal Closure ◽

Light Response ◽

Net Photosynthesis ◽

Response Curves ◽

Light Response Curves ◽

Leaf Surface Area ◽

Photosynthetic Responses

Relatively little work has been done to evaluate the effects of chronically high levels of carbon dioxide on growth and physiology of woody plants. In this study, seedlings of lodgepole pine (Pinuscontorta Dougl. var. latifoliaEngelm.) were grown for 5-month periods at 330, 1000, or 2000 μL CO2•L−1. Height growth; leaf area production; biomass of leaves, stems, and roots; and photosynthetic responses to changing light, moisture, and CO2 concentration were measured. Significant differences between treatments were found in mean seedling height on all measurement dates. Seedlings grown at 1000 μL CO2•L−1 were tallest, with seedlings grown in 2000 μL•L−1 intermediate between the control (330 μL•L−1) and 1000 μL•L−1 treatments. The same relationship was found in production of total leaf surface area. Increased leaf surface area yields a productive advantage to seedlings grown at concentrations of CO2 up to 2000 μL•L−1 even if no increase in net photosynthesis is assumed. Biomass of stems, roots, and secondary leaves was increased in both elevated CO2 conditions, with root biomass approximately 15 times greater in seedlings grown at 1000 μL•L−1 than in those grown at 330 μL•CO2•L−1. Stomatal resistances were essentially the same for all treatments, indicating no CO2-induced stomatal closure to at least 2000 μL•L−1. Photosynthetic Vmax (milligrams per square decimetre per hour) for light response curves varied with CO2 concentration. If results are extrapolated beyond a 5-month period and into field conditions, it appears that size of trees, interactions with competitors, and ecological role of the species might be altered.

Download Full-text

GROWTH, CARBON ACQUISITION, AND SOURCE-SINK RELATIONSHIPS IN `TITAN' RED RASPBERRY

HortScience ◽

10.21273/hortsci.29.4.248b ◽

1994 ◽

Vol 29 (4) ◽

pp. 248b-248 ◽

Cited By ~ 2

Author(s):

G. Fernandez ◽

M. Pritts

Keyword(s):

High Temperatures ◽

Light Response ◽

Dry Weight ◽

Yield Component ◽

Rubus Idaeus ◽

Partial Recovery ◽

Red Raspberry ◽

Response Curves ◽

Photosynthetic Rates ◽

Light Response Curves

Seasonal changes in growth, photosynthetic rates, temperature, and light response curves of `Titan' red raspberry (Rubus idaeus L.) were obtained from potted plants grown under field conditions. Primocane dry weight accumulation underwent two phases of linear growth at the beginning and the end of the season, but growth slowed during fruiting. This slower rate of dry weight accumulation also coincided with an increase in root dry weight. Primocane NAR and SLA were highest early in the season. Light response curves differed depending on cane type and time of year. Floricane photosynthetic rates (A) were high during the fruiting period, while primocane A rates remained steady throughout the season. Both primocane and floricane leaflets displayed a midday drop in A rate, with a partial recovery in late afternoon. Photosynthetic rates of both primocane and floricane leaves were very sensitive to high temperatures. Temporal convergence of sink demand from fruit, primocanes, and roots occurs when plants experience high temperatures. This may account for low realized yields in raspberry and the high level of yield component compensation typical of source-limited plants.

Download Full-text

Photosynthetic features of non-Kranz type C4 versus Kranz type C4 and C3 species in subfamily Suaedoideae (Chenopodiaceae)

Functional Plant Biology ◽

10.1071/fp09120 ◽

2009 ◽

Vol 36 (9) ◽

pp. 770 ◽

Cited By ~ 16

Author(s):

Monica E. Smith ◽

Nouria K. Koteyeva ◽

Elena V. Voznesenskaya ◽

Thomas W. Okita ◽

Gerald E. Edwards

Keyword(s):

Type Species ◽

C4 Photosynthesis ◽

Light Response ◽

Quantum Yields ◽

Response Curves ◽

Light Response Curves ◽

Unit Leaf ◽

Bienertia Sinuspersici ◽

C4 Species ◽

C3 Species

The objective of this study was to characterise photosynthesis in terrestrial non-Kranz (NK) C4 species, Bienertia sinuspersici Akhani and Suaeda aralocaspica (Bunge) Freitag & Schütze (formerly Borszczowia aralocaspica), compared with closely related Kranz type C4 Suaeda eltonica Iljin and Suaeda taxifolia Standley, and C3 species Suaeda heterophylla Bunge and Suaeda maritima Dumort in subfamily Suaedoideae (Chenopodiaceae). Traditional Kranz type C4 photosynthesis has several advantages over C3 photosynthesis under certain environmental conditions by suppressing photorespiration. The different photosynthetic types were evaluated under varying levels of CO2 and light at 25°C. Both NK and Kranz type species had C4 type CO2 compensation points (corrected for dark-type respiration) and half maximum saturation of photosynthesis at similar levels of atmospheric CO2 (average of 145 µbar for the C4 species v. 330 µbar CO2 for C3 species) characteristic of C4 photosynthesis. CO2 saturated rates of photosynthesis per unit chlorophyll was higher in the C3 (at ~2.5 current ambient CO2 levels) than the C4 species, which is likely related to their higher Rubisco content. The amount of Rubisco as a percentage of total protein was similar in NK and Kranz type species (mean 10.2%), but much lower than in the C3 species (35%). Light saturated rates of CO2 fixation per unit leaf area at 25°C and 340 µbar CO2 were higher in the Kranz species and the NK C4 S. aralocaspica than in the C3 species. In response to light at 340 µbar CO2, there was a difference in rates of photosynthesis per unit Rubisco with NK > Kranz > C3 species. There were no significant differences between the three photosynthetic types in maximum quantum yields, convexity of light response curves, and light compensation points at 25°C. The water use efficiency (CO2 fixed per water transpired) at 340 µbar CO2, 25°C and 1000 µmol quanta m–2 s–1 was on average 3-fold higher in the C4 (NK and Kranz) compared with the C3 species. The results show that the NK species have several C4 traits like the Kranz type species in subfamily Suaedoideae.

Download Full-text