scholarly journals Interspecific prediction of photosynthetic light response curves using specific leaf mass and leaf nitrogen content: effects of differences in soil fertility and growth irradiance

2012 ◽  
Vol 109 (6) ◽  
pp. 1149-1157 ◽  
Author(s):  
Pierre-Philippe Lachapelle ◽  
Bill Shipley
Keyword(s):  
Soil Fertility ◽  
Nitrogen Content ◽  
Light Response ◽  
Leaf Nitrogen ◽  
Leaf Nitrogen Content ◽  
Response Curves ◽  
Specific Leaf Mass ◽  
Leaf Mass ◽  
Light Response Curves ◽  
Growth Irradiance

Ecophysiological Studies on Six Species of the Mangrove Red Algal Genus Caloglossa

1993 ◽  
Vol 20 (6) ◽  
pp. 729 ◽  
Author(s):  
U Karsten ◽  
JA West
Keyword(s):  
Growth Pattern ◽  
Growth Response ◽  
Light Response ◽  
Response Curves ◽  
Light Response Curves ◽  
Growth Irradiance ◽  
Red Algal ◽  
Algal Genus ◽  
Osmotic Acclimation

Several aspects of the ecophysiology were compared in six eulittoral species of the mangrove red algal genus Caloglossa. The growth pattern in relation to different salt and light treatments, photosynthesis-irradiance curves, as well as the influence of salinity on the intracellular D-mannitol concentrations were studied. All Caloglossa isolates can be characterised as halotolerant due to a broad growth response under a range of salinities (5.3-70‰). The D-mannitol content of all isolates increased significantly with hypersaline treatments and decreased significantly with hyposaline treatments. These data indicate the strong involvement of this hexitol in the osmotic acclimation of Caloglossa. The growth-irradiance pattern and the photosynthesis-light response curves demonstrate an adaptation to shaded habitats for all species. All these physiological capabilities allow the successful colonisation of Caloglossa on various intertidal substrates.

Partitioning of Nitrogen Between and Within Leaves Grown Under Different Irradiances

1989 ◽  
Vol 16 (6) ◽  
pp. 533 ◽  
Author(s):  
JR Evans
Keyword(s):  
Nitrogen Content ◽  
Photosynthetic Rate ◽  
Protein Complexes ◽  
Leaf Nitrogen ◽  
High Irradiance ◽  
Leaf Nitrogen Content ◽  
Unit Leaf ◽  
Growth Irradiance ◽  
Pigment Protein Complexes ◽  
Nitrogen Contents

The distribution of nitrogen between leaves on individual plants of Phaseolus vulgaris and Cucumis sativus which were grown under different irradiances was examined. For Phaseolus, shading treatments were imposed on individual leaflets when they had reached one-third of full expansion. Adjacent leaflets were either grown under the same irradiance or had different irradiances imposed on them. The nitrogen content of leaves depended on their growth irradiance and not on the growth irradiance of adjacent leaflets, with more nitrogen being found in leaves grown under higher irradiance compared to those grown in shade. For Cucumis, the nitrogen contents of the leaves changed following the imposition of shading treatments. The experiment was repeated four times with different nitrate nutrient treatments, twice in combination with a pretreatment growth irradiance of 40% sunlight. The relative changes in leaf nitrogen content for each irradiance treatment were independent of changes to the leaf nitrogen content of the plant and of the growth irradiance prior to the shading treatments. Again, nitrogen contents were highest in leaves grown at high irradiance. Acclimation of individual leaves to their irradiance treatment was seen for both Phaseolus and Cucumis. Growth under shade resulted in lower rates of oxygen evolution per unit of chlorophyll, when measured at high irradiance, and increased partitioning of nitrogen into pigment-protein complexes. These two changes working in opposition to each other meant that for Cucumis, the relationship between photosynthetic capacity and nitrogen content was similar between irradiance treatments. For Phaseolus, the increased partitioning of nitrogen into pigment-protein complexes at low irradiance was not as great as the reduction in photosynthetic rate per unit of chlorophyll, so that the photosynthetic rate per unit leaf nitrogen was less for leaves grown under low irradiance compared to those grown under high irradiance. It is shown that acclimation to lower irradiance can increase the potential daily photosynthesis for a given leaf nitrogen content.

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.

Photosynthetic light-response curves

Planta ◽  
1993 ◽  
Vol 189 (2) ◽  
Author(s):  
E. �gren ◽  
J.R. Evans
Keyword(s):  
Light Response ◽  
Response Curves ◽  
Light Response Curves
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