Effects of leaf development and phosphorus supply on the photosynthetic characteristics of perennial legume species with pasture potential: modelling photosynthesis with leaf development

2010 ◽  
Vol 37 (8) ◽  
pp. 713 ◽  
Author(s):  
Lalith D. B. Suriyagoda ◽  
Hans Lambers ◽  
Megan H. Ryan ◽  
Michael Renton

Age-dependent changes in leaf photosynthetic characteristics (i.e. parameters of the light response curve (maximum photosynthetic rate (Pmax), quantum yield (Φ) and the convexity parameter (θ)), stomatal conductance (gs) and dark respiration rate (Rd)) of an exotic perennial legume, Medicago sativa L. (lucerne), and two potential pasture legumes native to Australia, Cullen australasicum (Schltdl.) J.W. Grime and Cullen pallidum A. Lee, grown in a glasshouse for 5 months at two phosphorus (P) levels (3 (P3) and 30 (P30) mg P kg–1 dry soil) were tested. Leaf appearance rate and leaf area were lower at P3 than at P30 in all species, with M. sativa being the most sensitive to P3. At any leaf age, photosynthetic characteristics did not differ between P treatments. However, Pmax and gs for all the species and Φ for Cullen species increased until full leaf expansion and then decreased. The convexity parameter, θ, did not change with leaf age, whereas Rd decreased. The estimates of leaf net photosynthetic rate (Pleaf) obtained through simulations at variable Pmax and Φ were lower during early and late leaf developmental stages and at lower light intensities than those obtained when Φ was assumed to be constant (e.g. for a horizontally placed leaf, during the 1500°C days developmental period, 3 and 19% reduction of Pleaf at light intensities of 1500 and 500 µmol m–2 s–1, respectively). Therefore, developmental changes in leaf photosynthetic characteristics should be considered when estimating and simulating Pleaf of these pasture species.

1982 ◽  
Vol 60 (12) ◽  
pp. 2734-2740 ◽  
Author(s):  
J. T. A. Proctor ◽  
J. M. Bodnar ◽  
W. J. Blackburn ◽  
R. L. Watson

Infestation of apple leaves with the spotted tentiform leafminer (STLM) reduced their net photosynthetic rate (Pn) over a range of light intensities. At a saturating irradiance level of 1240 μE∙m−2∙s−1 and 20 mines per leaf, 32.9% of the leaf area was injured but Pn was decreased by only 23.2%. Examination of parameters in a model for leaf photosynthesis showed a reduction in maximum photosynthetic rate (asymptotic value of the light-response curve) and mesophyll conductance but not in photochemical efficiency or dark respiration. The STLM injury had no effect on transpiration, stomatal conductance, and a slight effect on internal CO2 concentration and water-use efficiency. Mining reduced chlorophyll content of the leaves and this reduced the chlorophyll fluorescence of the mined areas. Tissue around the mines had a relatively high fluorescence reading confirming the Pn measurements and suggesting that this technique was suitable for these and similar studies. Mining by the STLM disrupts the photosynthetic apparatus of the leaf and affects a number of mechanisms in the photosynthetic process. Correlating these effects with field observations will help in determining economic thresholds for this insect.


1996 ◽  
Vol 121 (6) ◽  
pp. 1103-1111 ◽  
Author(s):  
Cheryl R. Hampson ◽  
Anita N. Azarenko ◽  
John R. Potter

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.


1972 ◽  
Vol 18 (12) ◽  
pp. 1825-1828 ◽  
Author(s):  
M. Takahashi ◽  
K. Shiokawa ◽  
S. Ichimura

Photosynthetic characteristics of a purple sulfur bacterium, Chromatium, strain D, cultured under various light intensities were examined. With a decrease in the light intensity used for culture, the bacteriochlorophyll a content per unit cell nitrogen increased. Also, at low light intensities, the rate of photosynthesis (per unit bacteriochlorophyll a) was higher in samples grown under low light than in those grown under high light. These two responses to low light intensity are adaptations that ensure a high photosynthetic rate for the purple sulfur bacterium that usually occurs in a dimly lit environment. Possible chemical and structural mechanisms involved are discussed.


2020 ◽  
Vol 41 (1) ◽  
pp. 61
Author(s):  
Ling Liao ◽  
Yi Ronga ◽  
Xia Qiua ◽  
Tiantian Donga ◽  
Zhihui Wang

Grafting is an effective measure to improve the photosynthetic rate of citrus. The light responses of photosynthesis in leaves of two-year old grafted Huangguogan (citrus cultivar Huangguogan), Huanggougan / Trifoliate (HG/PT), Huanggougan / Tangerine (HG/CR), and Huanggougan / Ziyang Xiangcheng (HG/CJ) were studied using the LI-COR 6400 portable photosynthesis system. Light-response curves and photosynthetic parameters were analyzed and fitted using the rectangular hyperbola model (RHM), the exponential model (EM), the non rectangular hyperbola model (NRHM), and the modified rectangular hyperbola model (MRHM). The results showed that: (1) Grafting can change the photosynthetic characteristics of Huangguogan, and the value of photosynthesis rate of HG/CJ is the greatest; (2) The light-response curves of net photosynthetic rate (PN), the light compensation point (LCP), and the dark respiration rate (RD) were well fitted using the above four models. The modified rectangular hyperbola was the best model in fitting the data; the nonrectangular hyperbola model was the second, and the rectangular hyperbola model was the poorest one.


HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1118D-1118
Author(s):  
Mark G. Lefsrud ◽  
Dean A. Kopsell

Chlorophyll and carotenoid pigments were measured with high-performance liquid chromatography (HPLC) during leaf development in kale (Brassicaoleracea L. var. acephala D.C). Lutein and β-carotene are two plant-derived carotenoids that possess important human health properties. Diets high in these carotenoids are associated with a reduced risk of cancer, cataracts, and age-related macular degeneration. Kale plants were growth-chamber grown in nutrient solution culture at 20 °C under 500 μmol·m-2·s-1 of irradiance. Pigments were measured in young (<1 week), immature (1-2 weeks), mature (2-3 weeks), fully developed (3-4 weeks) and senescing (>4 weeks) leaves. Significant differences were measured for all four pigments during leaf development. Accumulation of the pigments followed a quadratic trend, with maximum accumulation occurring between the first and third week of leaf age. The highest concentrations of lutein were recorded in 1- to 2-week-old leaves at 15.1 mg per 100 g fresh weight. The remaining pigments reached maximum levels at 2-3 weeks, with β-carotene at 11.6 mg per 100 g, chlorophyll a at 251.4 mg per 100 g, and chlorophyll b at 56.9 mg per 100 g fresh weight. Identifying changes in carotenoid and chlorophyll accumulation over developmental stages in leaf tissues is applicable to “baby” leafy greens and traditional production practices for fresh markets.


2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Jianshuang Gao ◽  
Shunyao Zhuang ◽  
Zhuangzhuang Qian

Plantation under the forest is a good way of agroforestry, but the canopy closure has a great influence on understory herbs’ growth. In the study, different canopy closures of Phyllostachys pubescens forests were set up to explore its influence on the growth of Ilex latifolia Thunb. The photosynthetic characteristics of Ilex latifolia leaves under different canopy closures were determined by Li-6400 portable photosynthetic system. The results showed that the net photosynthetic rate curve of Ilex latifolia leaves of T1 (canopy closure of 0.56) was bimodal with an obvious "midday depression" phenomenon, while the net photosynthetic rate curves of T2 (canopy closure of 0.72) and T3 (canopy closure of 0.86) were unimodal. The results of light response curve showed that the photosynthetically active radiation and transpiration rate reduced with the increasing of canopy closures. The photosynthetically active radiation, transpiration rate, stomatal conductance, and net photosynthetic rate of Ilex latifolia leaves of T2 were higher than those of T3. Although the net photosynthetic rate of T2 was lower than that of T1, it had no obvious photo-inhibition which affected plant growth. Overall, the canopy closure of 0.72 was more suitable for the growth of Ilex latifolia. The herb plantation in the bamboo forest should be considered with the canopy closure for a better growth.


Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 315
Author(s):  
Hailin Liu ◽  
Xin Han ◽  
Jue Ruan ◽  
Lian Xu ◽  
Bing He

The final size of plant leaves is strictly controlled by environmental and genetic factors, which coordinate cell expansion and cell cycle activity in space and time; however, the regulatory mechanisms of leaf growth are still poorly understood. Ginkgo biloba is a dioecious species native to China with medicinally and phylogenetically important characteristics, and its fan-shaped leaves are unique in gymnosperms, while the mechanism of G. biloba leaf development remains unclear. In this study we studied the transcriptome of G. biloba leaves at three developmental stages using high-throughput RNA-seq technology. Approximately 4167 differentially expressed genes (DEGs) were obtained, and a total of 12,137 genes were structure optimized together with 732 new genes identified. More than 50 growth-related factors and gene modules were identified based on DEG and Weighted Gene Co-expression Network Analysis. These results could remarkably expand the existing transcriptome resources of G. biloba, and provide references for subsequent analysis of ginkgo leaf development.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yinli Bi ◽  
Huili Zhou

AbstractA well-developed canopy structure can increase the biomass accumulation and yield of crops. Peanut seeds were sown in a soil inoculated with an arbuscular mycorrhizal fungus (AMF) and uninoculated controls were also sown. Canopy structure was monitored using a 3-D laser scanner and photosynthetic characteristics with an LI-6400 XT photosynthesis system after 30, 45 and 70 days of growth to explore the effects of the AMF on growth, canopy structure and photosynthetic characteristics and yield. The AMF colonized the roots and AMF inoculation significantly increased the height, canopy width and total leaf area of the host plants and improved canopy structure. AMF reduced the tiller angle of the upper and middle canopy layers, increased that of the lower layer, reduced the leaf inclination of the upper, middle and lower layers, and increased the average leaf area and leaf area index after 45 days of growth, producing a well-developed and hierarchical canopy. Moreover, AMF inoculation increased the net photosynthetic rate in the upper, middle and lower layers. Plant height, canopy width, and total leaf area were positively correlated with net photosynthetic rate, and the inclination angle and tiller angle of the upper leaves were negatively correlated with net photosynthetic rate. Overall, the results demonstrate the effects of AMF inoculation on plant canopy structure and net photosynthetic rate.


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