Xuhua
Zhong^*,
Kaiming Liang, Bilin Peng, Ka Tian, Xiaojuan Li, Nongrong Huang, Yanzhuo
Liu, Junfeng Pan

THE CROP JOURNAL

Abstract

Short
basal internodes are important for lodging resistance of rice (Oryza sativa
L.). Several canopy indices affect the elongation of basal internodes, but
uncertainty as to the key factors determining elongation of basal internodes
persists. The objectives of this study were (1) to identify key factors
affecting the elongation of basal internodes and (2) to establish a
quantitative relationship between basal internode length and canopy indices. An
inbred rice cultivar, Yinjingruanzhan, was grown in two split-plot field
experiments with three N rates (0, 75, and 150 kg N ha−1 in early season and 0,
90, and 180 kg N ha−1 in late season) as main plots, three seedling densities
(16.7, 75.0, and 187.5 seedlings m−2 ) as subplots, and three replications in
the 2015 early and late seasons in Guangzhou, China. Light intensity at base of
canopy (Lb), light quality as determined from red/far-red light ratio (R/FR),
light transmission ratio (LTR), leaf area index (LAI), leaf N concentration
(NLV) and final length of second internode (counted from soil surface upward)
(FIL) were recorded. Higher N rate and seedling density resulted in
significantly longer FIL. FIL was negatively correlated with Lb, LTR, and R/FR
(P < 0.01) and positively correlated with LAI (P < 0.01), but not
correlated with NLV (P > 0.05). Stepwise linear regression analysis showed
that FIL was strongly associated with Lb and LAI (R2 = 0.82). Heavy N
application to pot-grown rice at the beginning of first internode elongation
did not change FIL. We conclude that FIL is determined mainly by Lb and LAI at
jointing stage. NLV has no direct effect on the elongation of basal internodes.
N application indirectly affects FIL by changing LAI and light conditions in
the rice canopy. Reducing LAI and improving canopy light transmission at jointing
stage can shorten the basal internodes and increase the lodging resistance of
rice.

Keywords: Internode
elongation  Leaf area index  Light intensity  Light quality 
R/FR, Light transmission ratio  Leaf
N concentration

附件：Basal internode elongation of rice as affected by light intensity and leaf area