EFFECT OF TIMING OF ROOT PRUNING AND ROOT IBA APPLICATION ON LEAF MINERAL CONCENTRATION AND CANOPY LIGHT INTERCEPTION OF 'COX'S' ORANGE PIPPIN' APPLE TREES

2004 ◽  
pp. 51-57 ◽  
Author(s):  
J.B. Retamales ◽  
N.A. Hipps ◽  
C.J. Atkinson
Keyword(s):  
Light Interception ◽  
Root Pruning ◽  
Mineral Concentration ◽  
Apple Trees ◽  
Canopy Light Interception

scholarly journals 589 Summer Pruning Effects on Leaf and Whole Canopy Gas Exchange in Apple Trees

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 548C-548
Author(s):  
Kuo-Tan Li ◽  
Alan N. Lakso
Keyword(s):  
Photosynthetic Activity ◽  
Fruit Size ◽  
Light Interception ◽  
Light Penetration ◽  
Apple Trees ◽  
Carbon Supply ◽  
Shade Leaves ◽  
Reduced Light ◽  
Canopy Light Interception

Summer pruning is primarily used in apples to increase the light penetration into inner canopy to improve fruit color. However, summer pruning may reduce fruit size. We hypothesize that removing healthy exterior shoots reduces the whole-tree carbon supply in relation to pruning severity. If the crop load (i.e., demand) is high, fruit size and quality will be reduced. The effects of summer pruning on photosynthetic activity and recovery of shaded leaves after re-exposure were monitored on a range of exposures in canopies of `Empire' apple trees. The photosynthetic ability of leaves was positively related to its prepruning exposure. There was little recovery of photosynthetic activity of shade leaves until late growing season, indicating the re-exposure of shade leaves after summer pruning cannot replace the role of exterior leaves removed by pruning. Whole canopy net CO2 exchange (NCER) was measured on `Empire'/M9 trees with a commercial range of pruning severity. Reductions in NCER were approximately proportional to pruning severity and % leaf area removed and were as great as 60% in the most severe pruning. Canopy light interception decreased slightly. The effects on canopy NCER thus appeared to be primarily related to reduced photosynthetic efficiency and secondarily to reduced light interception.

scholarly journals 115 Nitrogen fertilizer effects on above ground sward characteristics and beef heifer performance from native warm-season grass blends

2020 ◽  
Vol 98 (Supplement_2) ◽  
pp. 26-27
Author(s):  
Caroline Chappell ◽  
Landon Marks ◽  
Katie Mason ◽  
Mary K Mullenix ◽  
Sandra L Dillard ◽  
...  
Keyword(s):  
Nutritive Value ◽  
Warm Season ◽  
Ground Cover ◽  
Application Rate ◽  
Light Interception ◽  
Botanical Composition ◽  
Forage Production ◽  
Beef Heifers ◽  
Fertilizer Application Rate ◽  
Canopy Light Interception

Abstract A 2-yr study was conducted at Black Belt Research and Extension Center in Marion Junction, AL, to evaluate the effect of nitrogen (N) fertilizer application rate on forage production characteristics, nutritive value, and animal performance of beef heifers grazing a mixture of native warm-season grasses (NWSG) including big bluestem, little bluestem, and indiangrass. Six, two-hectare plots were randomly assigned to one of two treatments (0 or 67 kg N ha-1 applied in early April; n = 3 replications per treatment). Paddocks were continuously stocked with four weaned Angus × Simmental beef heifers (initial BW 288 ± 7 kg) from late May/early June through mid-to-late August during 2018 (73 grazing d) and 2019 (70 grazing d), respectively. Put-and-take cattle were used to manage forage to a target of 38 cm. Forage mass and canopy heights were collected every two weeks during the trial. Visual ground cover ratings, canopy light interception, and botanical composition were measured at the beginning and end of the trial in each year. Hand-plucked samples were collected every two weeks during the grazing trial to determine forage nutritional value. Data were analyzed using the PROC MIXED procedure in SAS 9.4, and differences were declared significant when P ≤ 0.05. Nitrogen fertilized NWSG had greater crude protein (P < 0.0001), sward heights (P = 0.0003), and canopy light interception at the beginning of the season (P = 0.0049) compared to non-fertilized paddocks. However, there were no differences (P ≥ 0.05) among N-fertility treatments for mean forage mass, heifer ADG, or BCS across the 2-yr study. Botanical composition data indicated that indiangrass decreased from 64% to 61% (P = 0.0022) and weed pressure increased from 11% to 15% (P = 0.0064) across the summer grazing season. Canopy light interception decreased by 51% from early June to August in fertilized NWSG and 26% in unfertilized paddocks, respectively. These data illustrate that NWSG systems may provide a viable grazing system in the summer months under reduced N inputs.

scholarly journals Pasture characteristics of Italian ryegrass and milk production under different management strategies

2012 ◽  
Vol 47 (6) ◽  
pp. 863-868 ◽  
Author(s):  
Marcolino Frederico Miguel ◽  
Henrique Mendonça Nunes Ribeiro Filho ◽  
Steben Crestani ◽  
Fabiana da Rocha Ramos ◽  
Tereza Cristina Moraes Genro
Keyword(s):  
Dry Matter ◽  
Nutritional Value ◽  
Lolium Multiflorum ◽  
Management Strategies ◽  
Growing Season ◽  
Light Interception ◽  
Italian Ryegrass ◽  
Neutral Detergent Fiber ◽  
Low Light ◽  
Canopy Light Interception

The objective of this work was to assess the effects of the sward structure of Italian ryegrass (Lolium multiflorum), during the first grazing cycle, on its morphological and bromatological characteristics throughout the growing season, and on the performance of dairy cows. The treatments consisted of two structures obtained as a function of canopy-light interception: high-light interception (HLI) and low-light interception (LLI), with different pre-grazing heights in the first grazing cycle. Pasture was managed under rotational grazing with a herbage allowance not below 30 kg dry matter (DM) per cow per day. Three grazing cycles, with a grazing interval of 30 days, were evaluated. Pre-grazing herbage mass was greater (2,240 vs. 1,656 kg ha-1 DM), but the proportion of leaf blades was smaller (0.35 vs. 0.43) for HLI swards. Neutral detergent fiber (NDF) content and organic matter digestibility (OMD) were similar between treatments in the first grazing cycle, but in the second and third ones NDF was greater, and OMD lower, for the HLI swards. Milk yields were greater for cows grazing LLI swards (19.4 vs. 21.1 kg per day). Initial grazing with 90% of light interception promotes greater nutritional value in the subsequent cycles.

scholarly journals Tree light capture and spatial variability of understory light increase with species mixing and tree size heterogeneity

2016 ◽  
Vol 46 (7) ◽  
pp. 968-977 ◽  
Author(s):  
Gauthier Ligot ◽  
Aitor Ameztegui ◽  
Benoît Courbaud ◽  
Lluís Coll ◽  
Dan Kneeshaw
Keyword(s):  
Three Dimensional ◽  
Weighted Average ◽  
Structural Heterogeneity ◽  
Light Interception ◽  
Tree Size ◽  
Dimensional Structure ◽  
Transmitted Radiation ◽  
Long Run ◽  
Forest Heterogeneity ◽  
Canopy Light Interception

Mixed and multi-layered forest ecosystems are sometimes more productive than monospecific and single-layered ones. It has been suggested that trees of different species and sizes occupy complementary positions in space, which would act as a mechanism to increase canopy light interception and wood production. However, greater canopy light interception reduces the average amount and variability of transmitted radiation, offering fewer opportunities for all species to regenerate and to maintain forest heterogeneity in the long run. We investigated whether increasing overstory heterogeneity indeed results in greater canopy light interception and lower variability in transmittance. We modeled the three-dimensional structure of forest stands with three typical forest structures, 10 mixtures of four tree species, and three different basal areas. We used the forest light interception model SamsaraLight and performed three-way analyses of covariance to analyze the effects of the three varied components of forest heterogeneity. We found no evidence that increasing structural heterogeneity increases canopy light interception. However, the light interception by mixed canopies was greater than the weighted average of light interception by the corresponding pure canopies. Variability in transmittance increased in some cases with compositional heterogeneity and, to a lesser extent, with tree size inequalities. The advantage of heterogeneous forests is in opportunities for natural regeneration, as well as in opportunities to enhance canopy light interception.

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