Leaf morphology and photosynthetic rate in birch seedlings and stump sprouts

1990 ◽  
Vol 20 (7) ◽  
pp. 952-960 ◽  
Author(s):  
A. Kauppi ◽  
M. Kiviniitty ◽  
A. Ferm
Keyword(s):  
Nitrogen Content ◽  
Shoot Growth ◽  
Photosynthetic Capacity ◽  
Leaf Size ◽  
Growing Season ◽  
Optimum Temperature ◽  
Factors Affecting ◽  
Mesophyll Structure ◽  
Rate Of Photosynthesis ◽  
Seed Origin

Comparisons were made of the leaves of sprout-origin and seed-origin shoots of Betulapubescens Ehrh. and B. pendula Roth grown under constant or varying temperatures. Particular attention was paid to leaf structure and other factors affecting the rate of photosynthesis. Differences in shoot growth, leaf size, mesophyll structure, and chlorophyll and nitrogen content were observed between the sprouts and seedlings of both species over the course of the growing season. Many of these differences were reflected in the photosynthesis measurements. The sprouts of both species appeared to show a better photosynthetic capacity in their first growing season than the seedlings, and they continued their height growth longer into the autumn. A distinct decline in the level of photosynthesis took place during the growing season. The results suggest that perhaps because of their higher chlorophyll and nitrogen content, young sprouts benefit more from the extremes of temperature at the beginning and end of the growing season than seedlings of the same age. The optimum temperature was the same for sprouts and seedlings of both species. Whether the superior photosynthetic capacity of sprouts compared with seedlings is maintained in later years remains to be resolved.

Altitudinal effects on leaf traits and shoot growth of Betulaplatyphylla var. japonica

1995 ◽  
Vol 25 (11) ◽  
pp. 1881-1885 ◽  
Author(s):  
Gaku Kudo
Keyword(s):  
Shoot Growth ◽  
Leaf Size ◽  
Leaf Traits ◽  
Growing Season ◽  
Leaf Nitrogen ◽  
Leaf Life Span ◽  
N Concentration ◽  
Leaf N Concentration ◽  
Lower Site ◽  
Leaf N

Leaf demography, shoot growth, and seasonal changes of leaf size, specific leaf area, and leaf nitrogen (N) concentration of Betulaplatyphylla var. japonica Hara were compared at two altitudes (140 and 700 m above sea level). At the higher site, where the length of growing season was restricted, leaf life-span was shorter and leaf N concentration was higher throughout the growing season than at the lower site. Leaf size did not differ between sites. Production of short-lived and high N concentration leaves was considered adaptive under the condition of short growing season. At the higher site, N was translocated from senescing early leaves to late leaves in mid-September, whereas a significant increase in late leaf N concentration was not observed at the lower site. There were no differences in shoot growth, bud size, late leaf number on long shoots between sites, probably because of effective N use at the higher site.

Leaf and canopy CO2 assimilation in a West African humid savanna during the early growing season

1995 ◽  
Vol 11 (4) ◽  
pp. 529-545 ◽  
Author(s):  
X. Le Roux ◽  
P. Mordelet
Keyword(s):  
Leaf Area Index ◽  
Nitrogen Content ◽  
Leaf Area ◽  
Photosynthetic Capacity ◽  
Growing Season ◽  
West African ◽  
Grass Species ◽  
Area Index ◽  
Humid Savanna ◽  
Low Nitrogen

ABSTRACTLeaf and grass canopy photosynthetic rates were measured in a West African humid savanna during several stages of the early growing season. The results obtained on the dominant grass species Hyparrhenia diplandra and data published previously show that C4 savanna grasses exhibit a remarkably high leaf photosynthetic capacity despite their low nitrogen content. A variation of leaf photosynthetic capacity in relation to leaf rank on stems is observed which is interpreted by ageing and shading effects within the canopy. Seasonal variations of the canopy CO2 assimilation rate is explained in relation to variations of leaf area index and canopy nitrogen content. Despite low nitrogen content or low leaf area index, maximum canopy net photosynthesis was high (24 μmol CO2 m-3 s-1 for LAI = 1.5). The high photosynthetic nitrogen use efficiency exhibited by leaves of humid savanna grass species is a major attribute explaining high photosynthetic rates of the grass canopy in this environment. This result sustains the emerging opinion that tropical savannas could be highly productive despite the generally low nutrient status they experience.

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.

Assessing the impact of seasonal precipitation and temperature on vegetation in a grass-dominated rangeland

2014 ◽  
Vol 36 (2) ◽  
pp. 185 ◽  
Author(s):  
Fang Chen ◽  
Keith T. Weber
Keyword(s):  
Vegetation Index ◽  
Climatic Factors ◽  
Growing Season ◽  
Vegetation Growth ◽  
Factors Affecting ◽  
Growing Seasons ◽  
Normalised Difference Vegetation Index ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
The Impact ◽  
Precipitation And Temperature

Changes in vegetation are affected by many climatic factors and have been successfully monitored through satellite remote sensing over the past 20 years. In this study, the Normalised Difference Vegetation Index (NDVI), derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra satellite, was selected as an indicator of change in vegetation. Monthly MODIS composite NDVI at a 1-km resolution was acquired throughout the 2004–09 growing seasons (i.e. April–September). Data describing daily precipitation and temperature, primary factors affecting vegetation growth in the semiarid rangelands of Idaho, were derived from the Surface Observation Gridding System and local weather station datasets. Inter-annual and seasonal fluctuations of precipitation and temperature were analysed and temporal relationships between monthly NDVI, precipitation and temperature were examined. Results indicated NDVI values observed in June and July were strongly correlated with accumulated precipitation (R2 >0.75), while NDVI values observed early in the growing season (May) as well as late in the growing season (August and September) were only moderately related with accumulated precipitation (R2 ≥0.45). The role of ambient temperature was also apparent, especially early in the growing season. Specifically, early growing-season temperatures appeared to significantly affect plant phenology and, consequently, correlations between NDVI and accumulated precipitation. It is concluded that precipitation during the growing season is a better predictor of NDVI than temperature but is interrelated with influences of temperature in parts of the growing season.

Timing and rate of bud formation in Pinus resinosa

1971 ◽  
Vol 49 (10) ◽  
pp. 1821-1832 ◽  
Author(s):  
Edward Sucoff
Keyword(s):  
Quantitative Data ◽  
Shoot Growth ◽  
Pinus Resinosa ◽  
Growing Season ◽  
Axillary Buds ◽  
Growing Degree Days ◽  
Degree Days ◽  
Bud Formation ◽  
Late Season ◽  
Apical Dome

During the 1969 and 1970 growing season buds were collected almost weekly from matched trees in northeastern Minnesota. Cataphyll primordia for the year n + 1 shoot began forming at the time that internodes in the year n shoot started elongating (late April) and continued forming until early September. Primordia for axillary buds started forming about 2 months later and stopped forming at the same time as cataphylls. The size and deposition activity of the apical dome simultaneously increased during the early growing season and decreased during the late season. The maximum rates in July were over nine cataphylls per day.Rate of cataphyll deposition paralleled elongation of the needles on subtending shoots. Forty to fifty percent of the cataphylls had been formed when shoot growth was 95% complete. Although the bulk of the depositions occurred earlier in 1970, when growing degree days were used as the clock, the 2 years were similar.The results provide quantitative data to complement the histologic emphasis of previous studies.

CRITERIA AND INDICATORS OF VULNERABILITY OF AGRARIAN LAND USE SOILS TO DROUGHT TO DEVELOP MEASURES TO MITIGATE THEIR CONSEQUENCES (ON THE EXAMPLE OF THE BELARUSIAN POLESSYE REGION)

2020 ◽  
Author(s):  
Valentin Yatsukhno ◽  
◽  
Svetlana Bachila ◽  
Keyword(s):  
Land Use ◽  
Growing Season ◽  
Climatic Changes ◽  
Anthropogenic Factors ◽  
Agricultural Lands ◽  
Factors Affecting ◽  
Criteria And Indicators ◽  
Moisture Supply ◽  
Natural And Anthropogenic Factors

A system of criteria and indicators is proposed to determine the degree of vulnerability of soils of agricultural lands in Belarusian Polessye based on the analysis of climatic changes, natural and anthropogenic factors affecting their moisture supply during the growing season.

Some observations on the shoot growth of pine seedlings

1976 ◽  
Vol 6 (3) ◽  
pp. 341-347 ◽  
Author(s):  
S. Thompson
Keyword(s):  
Scots Pine ◽  
Shoot Apex ◽  
Shoot Growth ◽  
Lodgepole Pine ◽  
Growing Season ◽  
Pine Seedlings ◽  
Terminal Bud

Sequential observations in lodgepole pine (Pinuscontorta Dougl.) and Scots pine (P. sylvestris L.) showed that the second season's shoot was not produced solely from stem units in the terminal resting bud as previously assumed. The stem units held in the rosette of primary needles surrounding the terminal bud elongated to form most of the second season's shoot. The terminal bud only contributed 29 to 54% of the stem units. There was a marked difference between an inland and a coastal provenance of lodgepole pine in the appearance of the shoot apex at the end of the first growing season.

Factors Affecting Seed Germination and Seedling Emergence of Asia Minor Bluegrass (Polypogon fugax)

Weed Science ◽  
2015 ◽  
Vol 63 (2) ◽  
pp. 440-447 ◽  
Author(s):  
Xian Wu ◽  
Jun Li ◽  
Hongle Xu ◽  
Liyao Dong
Keyword(s):  
Seed Germination ◽  
Seedling Emergence ◽  
Late Summer ◽  
Asia Minor ◽  
Burial Depth ◽  
Optimum Temperature ◽  
Large Area ◽  
Factors Affecting ◽  
Temperature Regimes ◽  
Grass Weed

Little published information is available related to seed germination and seedling establishment of Asia Minor bluegrass, a problematic grass weed in some regions of China. The objective of this study was to examine the effects of different environmental factors on Asia Minor bluegrass seed germination. The optimum temperature for germination was around 10 to 20 C, and more than 90% of seeds germinated under 20/10 and 25/15 C temperature regimes. Also, light and pH did not appear to have any effect on seed germination. Asia Minor bluegrass was sensitive to osmotic stress, but tolerant of NaCl. No seedlings emerged when seeds were buried 4 cm deep. The result suggested that Asia Minor bluegrass has the potential to spread into a large area in China. To prevent its spreading, measures such as soil cultivation can be used to limit seed germination from increased burial depth and/or nonselective herbicides can be applied to kill early-germinating weed seedlings in late summer.

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