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.

Simulated optimal structure of a photosynthetic system: implication for the breeding of forest crop ideotype

1993 ◽  
Vol 23 (8) ◽  
pp. 1631-1638 ◽  
Author(s):  
Rong-Ling Wu
Keyword(s):  
Leaf Area Index ◽  
Nitrogen Content ◽  
Leaf Area ◽  
Photosynthetic Capacity ◽  
Optimal Structure ◽  
Relative Advantage ◽  
Uniform Structure ◽  
Leaf Nitrogen Content ◽  
Area Index ◽  
Photosynthetic System

A single leaf and canopy are two different levels of a photosynthetic system which have the function of carbon fixation and energy balance for plant and crop processes. A mechanistic model was derived to understand the photosynthetically based optimal structure for the maximization of whole-system nitrogen-use efficiency. The model is based upon the use of a nonrectangular hyperbola for leaf photosynthetic response to irradiance, the linear relationship of photosynthetic capacity with nitrogen content, and the Monsi–Saeki theory for the light-intercepting characteristics of the system. The whole-system carbon gain is maximized by partitioning of leaf nitrogen content (therefore photosynthetic capacity and other related physiological parameters) in terms of negatively exponential decrease with cumulative leaf area index, which has the same extinction rate with irradiance within the system. The biomass production of the photosynthetically based optimal structure (ideotype) and its relative advantage over uniform structure increase with increasing irradiance, nitrogen availability, and leaf area index. Such properties of ideotypes associated with leaf biology and geometry are discussed, as well as their application to short-rotation intensive culture in forest crops.

scholarly journals Analogy-Based Crop Yield Forecasts Based on Temporal Similarity of Leaf Area Index

2021 ◽  
Vol 13 (16) ◽  
pp. 3069
Author(s):  
Yadong Liu ◽  
Junhwan Kim ◽  
David H. Fleisher ◽  
Kwang Soo Kim
Keyword(s):  
Time Series ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Crop Yield ◽  
Satellite Data ◽  
Growing Season ◽  
Environmental Data ◽  
Area Index ◽  
Current Season ◽  
Wide Range

Seasonal forecasts of crop yield are important components for agricultural policy decisions and farmer planning. A wide range of input data are often needed to forecast crop yield in a region where sophisticated approaches such as machine learning and process-based models are used. This requires considerable effort for data preparation in addition to identifying data sources. Here, we propose a simpler approach called the Analogy Based Crop-yield (ABC) forecast scheme to make timely and accurate prediction of regional crop yield using a minimum set of inputs. In the ABC method, a growing season from a prior long-term period, e.g., 10 years, is first identified as analogous to the current season by the use of a similarity index based on the time series leaf area index (LAI) patterns. Crop yield in the given growing season is then forecasted using the weighted yield average reported in the analogous seasons for the area of interest. The ABC approach was used to predict corn and soybean yields in the Midwestern U.S. at the county level for the period of 2017–2019. The MOD15A2H, which is a satellite data product for LAI, was used to compile inputs. The mean absolute percentage error (MAPE) of crop yield forecasts was <10% for corn and soybean in each growing season when the time series of LAI from the day of year 89 to 209 was used as inputs to the ABC approach. The prediction error for the ABC approach was comparable to results from a deep neural network model that relied on soil and weather data as well as satellite data in a previous study. These results indicate that the ABC approach allowed for crop yield forecast with a lead-time of at least two months before harvest. In particular, the ABC scheme would be useful for regions where crop yield forecasts are limited by availability of reliable environmental data.

scholarly journals Effects of chlorine and potassium mineral nutrition on the leaf morphology of the PB 121 hybrid coconut palm (Malayan Yellow Dwarf x West African Tall)

CORD ◽  
2004 ◽  
Vol 20 (02) ◽  
pp. 34
Author(s):  
I. Mialet-Serra ◽  
X. Bonneau
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Mineral Nutrition ◽  
Leaf Morphology ◽  
West African ◽  
Petiole Length ◽  
Maximum Width ◽  
Area Index ◽  
Crown Area ◽  
Frond Length

The effects of chlorine and potassium on the leaf morphology of 6-year-old PB 121 hybrid coconut palms were studied in 1995 and 1996 in southern Lampung (South Sumatra, Indonesia). The parameters considered were frond and leaflet size (length, maximum width, area) and their number. Chlorine and potassium had an exclusive effect on leaflet size, increasing their area. Potassium primarily affected petiole length, hence total frond length. Synergy between these two ions only occurred for the number of leaflets. Chlorine and potassium acted independently on stem diameter and synergistically on height. Coconut palms receiving potassium or chlorine had significantly more voluminous leaf crowns. As time went by, this phenomenon increased despite constant monthly leaf emission. In a situation of equilibrium, the much larger mean crown area and leaf area index of coconuts receiving chlorine and potassium augured well for an earlier start to bearing and higher nut yields.

scholarly journals The effect of leaf area index on potatoes yield in soils contaminated by some heavy metals

2011 ◽  
Vol 48 (No. 7) ◽  
pp. 298-306
Author(s):  
M. Jůzl ◽  
M. Štefl
Keyword(s):  
Heavy Metals ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Significant Influence ◽  
Growth Analysis ◽  
Growing Season ◽  
Negative Influence ◽  
Field Conditions ◽  
Early Variety ◽  
Area Index

A&nbsp;method of growth analysis was used to evaluate the yield results in experiments conducted during years 1999&ndash;2001 on School co-operative farm in Žabčice. In sequential terms of sampling from two potato varieties with different duration of growing season, the effect of leaf area index (L, LAI), on yield of tubers in soils contaminated by cadmium, arsine and beryllium, was evaluated. From a&nbsp;growers view the phytotoxic influence on development of assimilatory apparatus and yields during the growth of a&nbsp;very-early variety Rosara and a&nbsp;medium-early Korela were evaluated. These varieties were grown under field conditions in soils contaminated by graded levels of cadmium, arsenic and beryllium. The yields of tubers were positively influenced by duration of growing season and increased of leaf area index during three experimental years. On the contrary, graded levels of heavy metals had negative influence on both chosen varieties. The highest phytotoxic influence was recorded of arsine and the lowest of cadmium. Significant influence of arsenic and beryllium on size of leaf area index in the highest applied variants was found. The influence of experimental years on tuber yields was also statistically significant.

Impact Assessment of Satellite-Derived Leaf Area Index Datasets Using a General Circulation Model

2007 ◽  
Vol 20 (6) ◽  
pp. 993-1015 ◽  
Author(s):  
Hyun-Suk Kang ◽  
Yongkang Xue ◽  
G. James Collatz
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
General Circulation ◽  
Circulation Model ◽  
West African ◽  
Radiative Energy ◽  
Area Index ◽  
Near Surface ◽  
Surface Climate ◽  
The Impact

Abstract This study assesses the impact of two different remote sensing–derived leaf area index (RSLAI) datasets retrieved from the same source (i.e., Advanced Very High Resolution Radiometer measurements) on a general circulation model’s (GCM) seasonal climate simulations as well as the mechanisms that lead to the improvement in simulations over several regions. Based on the analysis of these two RSLAI datasets for 17 yr from 1982 to 1998, their spatial distribution patterns and characteristics are discussed. Despite some disagreements in the RSLAI magnitudes and the temporal variability between these two datasets over some areas, their effects on the simulation of near-surface climate and the regions with significant impact are generally similar to each other. Major disagreements in the simulated climate appear in a few limited regions. The GCM experiment using the RSLAI and other satellite-derived land surface products showed substantial improvements in the near-surface climate in the East Asian and West African summer monsoon areas and boreal forests of North America compared to the control experiment that used LAI extrapolated from limited ground surveys. For the East Asia and northwest U.S. regions, the major role of RSLAI changes is in partitioning the net radiative energy into latent and sensible heat fluxes, which results in discernable warming and decrease of precipitation due to the smaller RSLAI values compared to the control. Meanwhile, for the West African semiarid regions, where the LAI difference between RSLAI and control experiments is negligible, the decrease in surface albedo caused by the high vegetation cover fraction in the satellite-derived dataset plays an important role in altering local circulation that produces a positive feedback in land/atmosphere interaction.

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