Contribution of overwintering leaves to the growth of three broad-leaved, evergreen shrubs belonging to the Ericaceae family

1978 ◽  
Vol 56 (10) ◽  
pp. 1248-1261 ◽  
Author(s):  
R. J. Reader
Keyword(s):  
Growing Season ◽  
Leaf Nitrogen ◽  
Leaf Nitrogen Content ◽  
Nitrogen And Phosphorus ◽  
Southern Ontario ◽  
Plant Parts ◽  
Mature Leaves ◽  
Growing Seasons ◽  
Labrador Tea ◽  
Ledum Groenlandicum

Individual leaves of three bog ericads, leatherleaf (Chamaedaphne calyculata), bog laurel (Kalmia polifolia), and Labrador tea (Ledum groenlandicum), were retained for a maximum of two growing seasons in a peat bog in southern Ontario. The premature loss of mature leaves, resulting from artificial defoliation, significantly reduced the growth of new shoots of L. groenlandicum and K. polifolia but not of C. calyculata. Defoliation effects were directly proportional to the normal retention time for overwintering leaves. Mature leaves probably translocate photosynthate, nitrogen, and phosphorus to other plant parts. This would explain why leaf dry weights were greatest at the start, rather than at the end, of the leaves' second growing season. Net photosynthetic rates decreased with leafage, but in terms of leaf nitrogen content, new and old leaves fixed equal amounts of carbon.

Effects of nitrogen fertilizer, shade, and the removal of new growth on longevity of overwintering bog ericad leaves

1980 ◽  
Vol 58 (16) ◽  
pp. 1737-1743 ◽  
Author(s):  
R. J. Reader
Keyword(s):  
Nutrient Availability ◽  
Nitrogen Fertilizer ◽  
Treatment Effects ◽  
Environmental Gradients ◽  
Growing Season ◽  
Interspecific Variation ◽  
Southern Ontario ◽  
Growing Seasons ◽  
Labrador Tea ◽  
Ledum Groenlandicum

Bog ericads, such as Labrador tea (Ledum groenlandicum), bog laurel (Kalmia polifolia), and leatherleaf (Chamaedaphne calyculata), retain individual leaves for two growing seasons in southern Ontario, presumably to facilitate nutrient movement between overlapping leaf cohorts. The objective of this study was to evaluate the effects of nutrient availability, shade, and the removal of new growth on the longevity of leaves during their second growing season. Longevity was extended significantly (p < 0.05) by removing new growth, but not by shading leaves (p > 0.05). The addition of nitrogen fertilizer increased only C. calyculata longevity. Interspecific variation in treatment effects appeared to be related to the positions occupied by the three species on environmental gradients. None of the experimentally treated leaves survived past the end of their second growing season, with the magnitude of treatment effects ranging from a reduction in longevity of 10 days to an increase of 25 days.

scholarly journals Estimating the Leaf Nitrogen Content with a New Feature Extracted from the Ultra-High Spectral and Spatial Resolution Images in Wheat

2021 ◽  
Vol 13 (4) ◽  
pp. 739
Author(s):  
Jiale Jiang ◽  
Jie Zhu ◽  
Xue Wang ◽  
Tao Cheng ◽  
Yongchao Tian ◽  
...  
Keyword(s):  
Nitrogen Content ◽  
Precision Agriculture ◽  
Field Experiments ◽  
Mean Squared Error ◽  
Growing Season ◽  
Leaf Nitrogen ◽  
Textural Analysis ◽  
Hyperspectral Images ◽  
Leaf Nitrogen Content ◽  
New Feature

Real-time and accurate monitoring of nitrogen content in crops is crucial for precision agriculture. Proximal sensing is the most common technique for monitoring crop traits, but it is often influenced by soil background and shadow effects. However, few studies have investigated the classification of different components of crop canopy, and the performance of spectral and textural indices from different components on estimating leaf nitrogen content (LNC) of wheat remains unexplored. This study aims to investigate a new feature extracted from near-ground hyperspectral imaging data to estimate precisely the LNC of wheat. In field experiments conducted over two years, we collected hyperspectral images at different rates of nitrogen and planting densities for several varieties of wheat throughout the growing season. We used traditional methods of classification (one unsupervised and one supervised method), spectral analysis (SA), textural analysis (TA), and integrated spectral and textural analysis (S-TA) to classify the images obtained as those of soil, panicles, sunlit leaves (SL), and shadowed leaves (SHL). The results show that the S-TA can provide a reasonable compromise between accuracy and efficiency (overall accuracy = 97.8%, Kappa coefficient = 0.971, and run time = 14 min), so the comparative results from S-TA were used to generate four target objects: the whole image (WI), all leaves (AL), SL, and SHL. Then, those objects were used to determine the relationships between the LNC and three types of indices: spectral indices (SIs), textural indices (TIs), and spectral and textural indices (STIs). All AL-derived indices achieved more stable relationships with the LNC than the WI-, SL-, and SHL-derived indices, and the AL-derived STI was the best index for estimating the LNC in terms of both calibration (Rc2 = 0.78, relative root mean-squared error (RRMSEc) = 13.5%) and validation (Rv2 = 0.83, RRMSEv = 10.9%). It suggests that extracting the spectral and textural features of all leaves from near-ground hyperspectral images can precisely estimate the LNC of wheat throughout the growing season. The workflow is promising for the LNC estimation of other crops and could be helpful for precision agriculture.

scholarly journals Modeling Canopy Carbon and Water Fluxes Using a Multilayered Model over a Temperate Meadow in Inner Mongolia

2019 ◽  
Vol 14 (1) ◽  
pp. 141-154
Author(s):  
Nina Chen ◽  
Anzhi Wang ◽  
Juan An ◽  
Yushu Zhang ◽  
Ruipeng Ji ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Environmental Factors ◽  
Vapor Pressure ◽  
Inner Mongolia ◽  
Saturated Vapor ◽  
Water Flux ◽  
Growing Season ◽  
Leaf Nitrogen ◽  
Leaf Nitrogen Content ◽  
Vegetation Characteristic

Abstract To incorporate canopy vertical structure in a process-based model over a temperate meadow, a multilayered model estimated canopy carbon flux (Fc) and water flux (LE) was applied by comparing with eddy covariance measurements in Inner Mongolia, China. Simulations of diurnal, seasonal CO2 and H2O fluxes and model sensitivity to parameters and variables were analyzed. The results showed that the model underestimated Fc and LE by about 0.6% and 5.0%, respectively. It was able to simulate the diurnal and seasonal variation of Fc and LE and performed well during the day and in the growing season, but poorly at night and early in the growing season. Fc was more sensitive to the leaf nitrogen content distribution coefficient and maximum catalytic activity of Rubisco, whereas LE showed greater sensitivity to the stomatal conductance parameter a1, empirical coefficient of stomatal response to saturated vapor pressure difference Vpds0, and minimum stomatal conductance of CO2gsc0. The response of Fc to environmental factors was ranked as air CO2 concentration (Ca) > air temperature (Ta) > photosynthetically active radiation (PAR) > soil water content (θsm) > vapor pressure deficit (VPD) > wind speed (u0). The response of LE to environmental factors was ranked as Ta > VPD > θsm> PAR> Ca> u0. The response of LE to vegetation characteristic parameters was greater than that of Fc.

Influence of agro-ecological service crop termination and synthetic biodegradable film covering on Aphis gossypii Glover (Rhynchota: Aphididae) infestation and natural enemy dynamics

2017 ◽  
Vol 33 (4) ◽  
pp. 386-392 ◽  
Author(s):  
Serena Magagnoli ◽  
Laura Depalo ◽  
Antonio Masetti ◽  
Gabriele Campanelli ◽  
Stefano Canali ◽  
...  
Keyword(s):  
Natural Enemies ◽  
Positive Impact ◽  
Nitrogen Concentration ◽  
Aphis Gossypii ◽  
Growing Season ◽  
Leaf Nitrogen ◽  
Biodegradable Film ◽  
Aphid Infestation ◽  
Growing Seasons ◽  
Ecological Service

AbstractAgro-ecological service crops (ASC) can increase the vegetation complexity of agroecosystems leading to a positive impact on natural enemies of arthropod pests and on weed control. In this study, two ASC terminations (green manure and roller crimper) and a Mater-Bi-mulched control (MB) were compared in order to describe the effects on pests and beneficial dynamics in an organic vegetable system. The trials were conducted over two consecutive growing seasons in 2014 and 2015. Zucchini were grown as cash crop and barley as ASC. Pests and natural enemies were monitored fortnightly by visual samplings along the whole zucchini-growing season. Zucchini plants showed a faster vegetative growth in MB treatment than in ASC terminations. In both years, MB plots were characterized by higher soil temperature and higher leaf nitrogen concentration resulting in plants more susceptible to Aphis gossypii infestations. In all the experimental plots, natural enemies controlled aphid infestations and no insecticide and sprays were necessary. In conclusion, the tested ASC techniques have been suggested as a tool to mitigate aphid infestation.

scholarly journals Isoprene emission from wetland sedges

2009 ◽  
Vol 6 (4) ◽  
pp. 601-613 ◽  
Author(s):  
A. Ekberg ◽  
A. Arneth ◽  
H. Hakola ◽  
S. Hayward ◽  
T. Holst
Keyword(s):  
Growing Season ◽  
Leaf Nitrogen ◽  
Temperature History ◽  
Emission Rates ◽  
Photosynthetic Gas Exchange ◽  
Allocation Pattern ◽  
Isoprene Emission ◽  
Growing Seasons ◽  
Environmental Controls ◽  
Carbon Dioxide Co2

Abstract. High latitude wetlands play an important role for the surface-atmosphere exchange of carbon dioxide (CO2) and methane (CH4), but fluxes of biogenic volatile organic compounds (BVOC) in these ecosystems have to date not been extensively studied. This is despite BVOC representing a measurable proportion of the total gaseous C fluxes at northern locations and in the face of the high temperature sensitivity of these systems that requires a much improved process understanding to interpret and project possible changes in response to climate warming. We measured emission of isoprene and photosynthetic gas exchange over two growing seasons (2005–2006) in a subarctic wetland in northern Sweden with the objective to identify the physiological and environmental controls of these fluxes on the leaf scale. The sedge species Eriophorum angustifolium and Carex rostrata were both emitters of isoprene. Springtime emissions were first detected after an accumulated diurnal mean temperature above 0°C of about 100 degree days. Maximum measured growing season standardized (basal) emission rates (20°C, 1000 μmol m−2 s−1) were 1075 (2005) and 1118 (2006) μg C m−2 (leaf area) h−1 in E. angustifolium, and 489 (2005) and 396 (2006) μg C m−2 h−1 in C. rostrata. Over the growing season, basal isoprene emission varied in response to the temperature history of the last 48 h. Seasonal basal isoprene emission rates decreased with leaf nitrogen (N), which may be explained by the typical growth and resource allocation pattern of clonal sedges as the leaves age. The observations were used to model emissions over the growing season, accounting for effects of temperature history, links to leaf assimilation rate and the light and temperature dependencies of the cold-adapted sedges.

scholarly journals Leaf isoprene emission in a subarctic wetland sedge community

2008 ◽  
Vol 5 (6) ◽  
pp. 5061-5091 ◽  
Author(s):  
A. Ekberg ◽  
A. Arneth ◽  
H. Hakola ◽  
S. Hayward ◽  
T. Holst
Keyword(s):  
Growing Season ◽  
Leaf Nitrogen ◽  
Temperature History ◽  
Emission Rates ◽  
Photosynthetic Gas Exchange ◽  
Allocation Pattern ◽  
Isoprene Emission ◽  
Growing Seasons ◽  
Environmental Controls ◽  
Carbon Dioxide Co2

Abstract. High latitude wetlands play an important role for the surface-atmosphere exchange of carbon dioxide (CO2) and methane (CH4), but fluxes of biogenic volatile organic compounds (BVOC) in these ecosystems have to date not been extensively studied. This is despite BVOC representing a measurable proportion of the total gaseous C fluxes at northern locations and in the face of the high temperature sensitivity of these systems that requires a much improved process understanding to interpret and project possible changes in response to climate warming. We measured emission of isoprene and photosynthetic gas exchange over two growing seasons (2005–2006) in a subarctic wetland in northern Sweden with the objective to identify the physiological and environmental controls of these fluxes on the leaf scale. The sedge species Eriophorum angustifolium and Carex rostrata were both emitters of isoprene, and springtime emissions were first detected after an accumulated diurnal mean temperature above 0°C of about 100 degree days. Maximum measured growing season standardized (basal) emission rates (20°C, 1000 μmol m−2 s−1) were 1075 (2005) and 1118 (2006) μg C m−2 (leaf area) h−1 in E. angustifolium, and 489 (2005) and 396 (2006) μg C m−2 h−1 in C. rostrata. Over the growing season, basal isoprene emission varied in response to the temperature history of the last 48 h. Seasonal basal isoprene emission rates decreased also with leaf nitrogen (N), which may be explained by the typical growth and resource allocation pattern of clonal sedges as the leaves age. The observations were used to model emissions over the growing season, accounting for effects of temperature history, links to leaf assimilation rate and the light and temperature dependencies of the cold-adapted sedges.

scholarly journals Leaf Nitrogen Content, Photosynthesis and Radiation Use Efficiency in Peanut1

1993 ◽  
Vol 20 (1) ◽  
pp. 40-43 ◽  
Author(s):  
T. R. Sinclair ◽  
J. M. Bennett ◽  
K. J. Boote
Keyword(s):  
Nitrogen Content ◽  
Field Tests ◽  
Positive Association ◽  
Growing Season ◽  
Leaf Nitrogen ◽  
Radiation Use Efficiency ◽  
Leaf Nitrogen Content ◽  
Wide Range ◽  
Use Efficiency ◽  
Radiation Use

Abstract It has been hypothesized that a close correlation exists between specific leaf nitrogen content (SLN, g N m-2 leaf area) and leaf carbon exchange rate (CER), and crop radiation use efficiency (RUE). This association has not been investigated previously in peanut (Arachis hypogaea L.) so the objective of this research was to obtain such data under greenhouse and field conditions. In the greenhouse study differing nitrogen fertilizer treatments for a non-nodulated cultivar resulted in leaves with a wide range of SLN and CER. A strong, positive association between SLN and CER was found. In the field little variation in either SLN or CER was observed through much of the growing season in four commercial cultivars. Consistent with the observation of stability in SLN and CER, RUE based on total, intercepted solar radiation was found to be constant at 1.00 g MJ-1 through the growing season. However, the observed RUE was 29% greater than a theoretical RUE calculated assuming a uniform distribution of SLN in the canopy. One possibility is that RUE of peanuts may be enhanced by a nonuniform SLN distribution within its leaf canopy. In any event, the results of both the greenhouse and field tests showed that peanut CO2 assimilation is closely linked to leaf SLN.

scholarly journals The Relationship between Leaf Nitrogen Content and Photosynthesis in Apple Leaves

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 578c-578
Author(s):  
Lailiang Cheng ◽  
Sunghee Guak ◽  
Leslie H. Fuchigami
Keyword(s):  
Nitrogen Content ◽  
Net Photosynthesis ◽  
Leaf Nitrogen ◽  
Leaf Nitrogen Content ◽  
Nitrogen And Phosphorus ◽  
N Content ◽  
Wide Range ◽  
Leaf N Content ◽  
The Relationship ◽  
Leaf N

Fertigation of young Fuji/M26 apple trees (Malus domestica Borkh.) with different nitrogen concentrations by using a modified Hoagland solution for 6 weeks resulted in a wide range of leaf nitrogen content in recently expanded leaves (from 0.9 to 4.4 g·m–2). Net photosynthesis at ambient CO2, carboxylation efficiency, and CO2-saturated photosynthesis of recently expanded leaves were closely related to leaf N content expressed on both leaf area and dry weight basis. They all increased almost linearly with increase in leaf N content when leaf N < 2.4 g·m–2, leveled off when leaf N increased further. The relationship between stomatal conductance and leaf N content was similar to that of net photosynthesis with leaf N content, but leaf intercellular CO2 concentration tended to decrease with increase in leaf N content, indicating non-stomatal limitation in leaves with low N content. Photosynthetic nitrogen use efficiency was high when leaf N < 2.4 g·m–2, but decreased with further increase in leaf N content. Due to the correlation between leaf nitrogen and phosphorus content, photosynthesis was also associated with leaf P content, but to a lesser extent.

scholarly journals Growth Responses of Boreal Scots Pine, Norway Spruce and Silver Birch Seedlings to Simulated Climate Warming over Three Growing Seasons in a Controlled Field Experiment

Forests ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 943
Author(s):  
Katri Nissinen ◽  
Virpi Virjamo ◽  
Antti Kilpeläinen ◽  
Veli-Pekka Ikonen ◽  
Laura Pikkarainen ◽  
...  
Keyword(s):  
Norway Spruce ◽  
Scots Pine ◽  
Root Biomass ◽  
Growing Season ◽  
Silver Birch ◽  
Shoot Biomass ◽  
Growth Responses ◽  
Growing Seasons ◽  
Simulated Climate ◽  
Shoot And Root Biomass

We studied the growth responses of boreal Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies L. Karst.) and silver birch (Betula pendula Roth) seedlings to simulated climate warming of an average of 1.3 °C over the growing season in a controlled field experiment in central Finland. We had six replicate plots for elevated and ambient temperature for each tree species. The warming treatment lasted for the conifers for three growing seasons and for the birch two growing seasons. We measured the height and diameter growth of all the seedlings weekly during the growing season. The shoot and root biomass and their ratios were measured annually in one-third of seedlings harvested from each plot in autumn. After two growing seasons, the height, diameter and shoot biomass were 45%, 19% and 41% larger in silver birch seedlings under the warming treatment, but the root biomass was clearly less affected. After three growing seasons, the height, diameter, shoot and root biomass were under a warming treatment 39, 47, 189 and 113% greater in Scots pine, but the root:shoot ratio 29% lower, respectively. The corresponding responses of Norway spruce to warming were clearly smaller (e.g., shoot biomass 46% higher under a warming treatment). As a comparison, the relative response of height growth in silver birch was after two growing seasons equal to that measured in Scots pine after three growing seasons. Based on our findings, especially silver birch seedlings, but also Scots pine seedlings benefitted from warming, which should be taken into account in forest regeneration in the future.

Smallseed Falseflax (Camelina microcarpa) Management in Oklahoma Winter Wheat

2021 ◽  
pp. 1-14
Author(s):  
Jodie A. Crose ◽  
Misha R. Manuchehri ◽  
Todd A. Baughman
Keyword(s):  
Winter Wheat ◽  
Weed Control ◽  
Herbicide Resistance ◽  
Wheat Yield ◽  
Acetolactate Synthase ◽  
Growing Season ◽  
Time Of Application ◽  
Adequate Control ◽  
Growing Seasons

Abstract Three herbicide premixes have recently been introduced for weed control in wheat. These include: halauxifen + florasulam, thifensulfuron + fluroxypyr, and bromoxynil + bicyclopyrone. The objective of this study was to evaluate these herbicides along with older products for their control of smallseed falseflax in winter wheat in Oklahoma. Studies took place during the 2017, 2018, and 2020 winter wheat growing seasons. Weed control was visually estimated every two weeks throughout the growing season and wheat yield was collected in all three years. Smallseed falseflax size was approximately six cm in diameter at time of application in all years. Control ranged from 96 to 99% following all treatments with the exception of bicyclopyrone + bromoxynil and dicamba alone, which controlled falseflax 90%. All treatments containing an acetolactate synthase (ALS)-inhibiting herbicide achieved adequate control; therefore, resistance is not suspected in this population. Halauxifen + florasulam and thifensulfuron + fluroxypyr effectively controlled smallseed falseflax similarly to other standards recommended for broadleaf weed control in wheat in Oklahoma. Rotational use of these products allows producers flexibility in controlling smallseed falseflax and reduces the potential for development of herbicide resistance in this species.

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