Correlation of Leaf Area Index to Root Biomass in Populus tremuloides Michx supports the Pipe Model Theory

2017 ◽  
Vol 06 (04) ◽  
Author(s):  
Caldwell BT ◽  
O Hara KL
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Populus Tremuloides ◽  
Model Theory ◽  
Root Biomass ◽  
Area Index ◽  
Pipe Model ◽  
Pipe Model Theory

scholarly journals Response of Rice Genotypes to Weed Competition in Dry Direct-Seeded Rice in India

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Gulshan Mahajan ◽  
Mugalodi S. Ramesha ◽  
Bhagirath S. Chauhan
Keyword(s):  
Grain Yield ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Root Biomass ◽  
Early Stage ◽  
Weed Competition ◽  
Genotypic Differences ◽  
Area Index ◽  
Direct Seeded ◽  
Rice Genotypes

The differential weed-competitive abilities of eight rice genotypes and the traits that may confer such attributes were investigated under partial weedy and weed-free conditions in naturally occurring weed flora in dry direct-seeded rice during the rainy seasons of 2011 and 2012 at Ludhiana, Punjab, India. The results showed genotypic differences in competitiveness against weeds. In weed-free plots, grain yield varied from 6.6 to 8.9 t ha−1across different genotypes; it was lowest for PR-115 and highest for the hybrid H-97158. In partial weedy plots, grain yield and weed biomass at flowering varied from 3.6 to 6.7 t ha−1and from 174 to 419 g m−2, respectively. In partial weedy plots, grain yield was lowest for PR-115 and highest for PR-120. Average yield loss due to weed competition ranged from 21 to 46% in different rice genotypes. The study showed that early canopy closure, high leaf area index at early stage, and high root biomass and volume correlated positively with competitiveness. This study suggests that some traits (root biomass, leaf area index, and shoot biomass at the early stage) could play an important role in conferring weed competitiveness and these traits can be explored for dry-seeded rice.

scholarly journals Crown allometry and application of the pipe model theory to white spruce (Picea glauca (Moench) Voss) and aspen (Populus tremuloides Michx.) in the western boreal forest of Canada

2016 ◽  
Vol 46 (2) ◽  
pp. 262-273 ◽  
Author(s):  
Derek F. Sattler ◽  
Philip G. Comeau
Keyword(s):  
Boreal Forest ◽  
Populus Tremuloides ◽  
Model Theory ◽  
Picea Glauca ◽  
White Spruce ◽  
Allometric Relationship ◽  
Sapwood Area ◽  
Crown Length ◽  
Pipe Model ◽  
Pipe Model Theory

White spruce (Picea glauca (Moench) Voss) and aspen (Populus tremuloides Michx.) from unmanaged stands in the boreal forest of Alberta, Canada, were examined for two of the main structural assumptions in the process-based model CROBAS: (i) a constant allometric relationship between foliage mass and crown length and (ii) a constant relationship between foliage mass and sapwood area. We evaluated these relationships at both at the whole-crown and within-crown levels. Results indicated that for both species, a constant allometric relationship between foliage mass and crown length was maintained at the whole-crown level over a period exceeding the peak mean annual increment of each species. Within the crowns of spruce, foliage mass accumulated faster near the tree apex as total crown length increased. For aspen, the increase in foliage mass per unit crown length for any section within the crown showed greater similarity to the relationship observed at the whole-crown level. The assumption of a constant relationship between foliage mass and sapwood area at the crown base generally held for spruce but showed considerable variation for any given diameter class. For aspen, this assumption did not appear to be appropriate. For both species, there was more foliage mass per unit sapwood area with increasing height from the ground for nearly all tree size classes. This latter finding was in conflict with the pipe model theory but could not be explained by the hydraulic theory of crown architecture, which predicts a decrease in the ratio of foliage mass to sapwood area with increasing path length.

Application of the pipe model theory to predict canopy leaf area

1982 ◽  
Vol 12 (3) ◽  
pp. 556-560 ◽  
Author(s):  
R. H. Waring ◽  
P. E. Schroeder ◽  
R. Oren
Keyword(s):  
Leaf Area ◽  
Model Theory ◽  
Large Fraction ◽  
Cross Sectional Area ◽  
Unit Weight ◽  
Sectional Area ◽  
Cross Sectional ◽  
Sapwood Area ◽  
Pipe Model ◽  
Pipe Model Theory

The pipe model theory presents the idea that a unit weight of tree foliage is serviced by a specific cross-sectional area of conducting sapwood in the crown. Below the crown, a large fraction of the tree bole may be nonconducting tissue, so the sapwood area would have to be known to estimate foliage. We applied the pipe model theory to the analysis of several western coniferous species to learn whether the distribution of canopy leaf area could be accurately estimated from knowledge of the sapwood cross-sectional area at various heights, including breast height (1.37 m). Results are excellent, but taper in the conducting area must be considered when sapwood area is measured below the crown.

RESPONSE OF CASSAVA TO PROLONGED WATER STRESS IMPOSED AT DIFFERENT STAGES OF GROWTH

2002 ◽  
Vol 38 (3) ◽  
pp. 333-350 ◽  
Author(s):  
M. A. El-Sharkawy ◽  
L. F. Cadavid
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Root Biomass ◽  
Nitrogen Concentration ◽  
Nutrient Use Efficiency ◽  
Root Production ◽  
Shoot Biomass ◽  
Area Index ◽  
Nutrient Use ◽  
Use Efficiency

A two-year field trial was conducted to study the effects of prolonged water stress on cassava (Manihot esculenta) productivity, and on nutrient uptake and use efficiency. Four contrasting cultivars were supplied with adequate fertilization and watering, except when water was excluded by covering the soil with plastic sheets for different periods, depending on treatment: from two to six months, four to eight months, or from six to twelve months after planting (early, mid-season and terminal stress respectively). Sequential harvests were made at 2, 4, 6, 8 and 12 months after planting to determine leaf area index and shoot and root biomass. At final harvest, nitrogen, phosphorus, potassium, calcium and magnesium concentrations in shoots and storage roots were determined.During both early and mid-season stress, leaf area index and shoot and root biomass were significantly smaller than those in the controls across all cultivars. After recovery from stress, leaf area index was greatly enhanced with less dry matter allocated to stems, and root yields approached those in the controls. One cultivar, CMC 40, had greater final root yield under stress treatments. Nutrient concentration in roots and shoots was less in all cultivars with early stress and resulted in higher nutrient use efficiency in all elements for root production. The same trend was observed under mid-season stress, except for nitrogen concentration, which remained unchanged.Terminal stress did not affect leaf area index, but reduced the shoot biomass in all cultivars. Final root yields were smaller than those in the controls except for CMC 40 whose final root yield was greater under stress. Nitrogen concentration was greater in root biomass but less in shoot biomass of all cultivars, resulting in lower nitrogen–use efficiency for root production. Across cultivars, only potassium- and magnesium-use efficiencies were greater than in the controls. CMC 40 was the only cultivar with consistently greater use efficiency of nitrogen, phosphorus, potassium, calcium and magnesium for root production under terminal stress. This higher nutrient use efficiency was due, mainly, to a greater root production rather than to smaller nutrient concentration. This cultivar is suitable as a gene source for improving cassava in order to maximize root production per unit nutrient extracted under stressful environmental conditions.

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