对太阳辐射的拦截叶形状的影响 The effect of leaf shape on the interception of sol

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The effect of leaf shape on the interception of solar radiation
C.B.S. Teh*
Department of Land Management, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor,
- u; b! g# C# M5 R0 SMalaysia
5 Abstract
One of the properties of canopy architecture is leaf shape, and its effect on solar radiation
, p; K- @7 [, y4 Zinterception by a plant is little understood and studied. Consequently, this study was to evaluate
4 p) D. p0 V4 C# U" u7 ?+ n% Uthe effect of six leaf shapes on both direct and diffuse solar radiation interception using a
detailed 3-D solar radiation model. Six hypothetical plant prototypes were computer-generated
10 so that each prototype was equal to each other in all aspects; only the leaf shape for each
) B+ }* c1 J% k- \prototype was varied. The leaf shapes selected were round (RD), square (SQ), triangle (TR),
5 n. t/ Q$ V  W4 Linverted triangle (ITR), ellipse (EL) and lobe (LB). Computer simulations revealed that leaf
shape did have an effect on direct and diffuse solar radiation interception. However, its effect
$ ~3 R- @0 ]& z1 `# W" Owas to a rather small extent of not more than 11% increase in solar radiation interception. The
0 v: `5 e, _+ d, Z" s! u& u15 mean hourly interception of solar radiation by the prototypes decreased in the following
: a6 z; q# _* {$ a/ Q% Umanner: (ITR ≈ EL) > (RD ≈ SQ ≈ TR ≈ LB). Although leaf lobbing is often hypothesised to
produce deeper sunflecks within the canopy, this study however revealed that leaf lobbing per
( m% d3 x! \6 r; c! m) o% A9 Q3 @se had no effect on solar radiation interception. All properties being equal, solar radiation
, M9 x. s, H6 J' @interception could be increased by having leaf shapes that are: 1) long and narrow, 2) broader at
" w/ F6 I4 f0 }20 the apex than at the basal, and 3) supported by leaf petioles. These three conditions increase
& n  E5 B6 p' `5 N: Gsolar radiation interception by causing the canopy to be spread out more uniformly in the aerial
space; this, in turn, means less leaf clustering and self-shading. However, the effect of leaf
7 H; s9 j& d" D+ i+ Mshape on solar radiation interception decreases for near or full canopy cover because at this
/ a7 q9 k% A0 }' x$ Fstage, the canopy is already intercepting solar radiation at near maximum capacity. Leaf shape
( o: p" K* L6 a/ l25 also did not affect the diurnal variation of direct and diffuse solar radiation interception. This
$ @* h, l- z- f- I  t, ustudy may help to better select crop varieties having the “proper leaf form” for optimum plant
- A# D5 J1 k* Kproduction, as well as to better understand plant adaptation mechanisms in response to
environmental stresses.
2 A& K( [% a( |' n- Q" y0 Z/ g1 }Keywords: leaf shape; solar radiation; Beer’s law; canopy architecture
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