The effect of leaf shape on the interception of solar radiation. A7 I0 Y0 `4 c$ T
C.B.S. Teh* % @& Q" t; t0 ~1 c0 s" M g0 hDepartment of Land Management, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor,/ d1 k- D' I" B9 @) b
Malaysia ; D2 t! b. f# d9 z% s$ W5 Abstract; D' v4 s; x$ W& R- K
One of the properties of canopy architecture is leaf shape, and its effect on solar radiation: F: V& w1 Z f) b9 O- e" X
interception by a plant is little understood and studied. Consequently, this study was to evaluate ! N7 |8 w1 R* C9 q# h. \, P, q' zthe effect of six leaf shapes on both direct and diffuse solar radiation interception using a1 y7 X& }& J( h! m
detailed 3-D solar radiation model. Six hypothetical plant prototypes were computer-generated6 Q3 s: z M6 y. V0 b: v
10 so that each prototype was equal to each other in all aspects; only the leaf shape for each4 y. s/ J& t/ A
prototype was varied. The leaf shapes selected were round (RD), square (SQ), triangle (TR),8 z* k2 D5 [* H* S" i8 k& j: k; Y
inverted triangle (ITR), ellipse (EL) and lobe (LB). Computer simulations revealed that leaf2 w) x3 ?3 D$ y/ N8 p, P; o# t
shape did have an effect on direct and diffuse solar radiation interception. However, its effect ! a5 \) A; {& l9 F. r4 Mwas to a rather small extent of not more than 11% increase in solar radiation interception. The. j; F6 }: X$ J7 e: d t2 V
15 mean hourly interception of solar radiation by the prototypes decreased in the following 0 ^; P3 B0 G& j* b, n1 k ^% Rmanner: (ITR ≈ EL) > (RD ≈ SQ ≈ TR ≈ LB). Although leaf lobbing is often hypothesised to 7 s# u, U' C# m. S- oproduce deeper sunflecks within the canopy, this study however revealed that leaf lobbing per8 s8 L9 w) L+ X- ]8 P, V3 d
se had no effect on solar radiation interception. All properties being equal, solar radiation 4 [3 j: O3 ^" f- ^- Xinterception could be increased by having leaf shapes that are: 1) long and narrow, 2) broader at* P$ n( R& V" {" h7 B4 i4 n
20 the apex than at the basal, and 3) supported by leaf petioles. These three conditions increase / L2 D" L B9 B! U1 `$ S! Osolar radiation interception by causing the canopy to be spread out more uniformly in the aerial. f g6 F( J9 H0 h2 O/ G @( w
space; this, in turn, means less leaf clustering and self-shading. However, the effect of leaf: z5 N; `" M6 ]3 E3 w8 k
shape on solar radiation interception decreases for near or full canopy cover because at this ( h0 H( V0 r [stage, the canopy is already intercepting solar radiation at near maximum capacity. Leaf shape 5 `8 F; E+ J: t( F- ~25 also did not affect the diurnal variation of direct and diffuse solar radiation interception. This d g, ~! S1 u' [ R9 `study may help to better select crop varieties having the “proper leaf form” for optimum plant$ d' h/ z: h7 r. F% m9 H- U; Z
production, as well as to better understand plant adaptation mechanisms in response to - |. [5 [# b1 Q/ X `* S' Qenvironmental stresses.. P" d" f" n- x; B. r4 G
Keywords: leaf shape; solar radiation; Beer’s law; canopy architecture. C$ T- D$ a' k
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发表于 2014-12-8 17:09
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