Limitation of Unloading in the Developing Grains Is a Possible Cause Responsible for Low Stem Non-structural Carbohydrate Translocation and Poor Grain Yield Formation in Rice through Verification of Recombinant Inbred Lines
Guohui
Li1, Junfeng Pan1†, Kehui Cui1,2*, Musong Yuan1,
Qiuqian Hu1, Wencheng Wang1, Pravat K. Mohapatra3,
Lixiao Nie1,2, Jianliang Huang1,2 and Shaobing Peng1
Frontiers in Plant
Science
Abstract
Remobilisation
of non-structural carbohydrates (NSC) from leaves and stems and unloading into
developing grains are essential for yield formation of rice. In present study,
three recombinant inbred lines of rice, R91, R156 and R201 have been tested for
source-flow-sink related attributes determining the nature of NSC accumulation
and translocation at two nitrogen levels in the field. Compared to R91 and
R156, R201 had lower grain filling percentage, harvest index, and grain yield.
Meanwhile, R201 had significantly lower stem NSC translocation during grain
filling stage. Grain filling percentage, harvest index, and grain yield showed
the consistent trend with stem NSC translocation among the three lines. In
comparison with R91 and R156, R201 had similarity in leaf area index, specific
leaf weight, stem NSC concentration at heading, biomass, panicles m-2,
spikelets per panicle, remobilization capability of assimilation in stems, sink
capacity, sink activity, number and cross sectional area of small vascular bundles,
greater number and cross sectional area of large vascular bundles, and higher SPAD,
suggesting that source, flow, and sink were not the limiting factors for low
stem NSC translocation and grain filling percentage of R201. However, R201 had
significant higher stem and rachis NSC concentrations at maturity, which
implied that unloading in the developing grains might result in low NSC
translocation in R201. The results indicate that stem NSC translocation could
be beneficial for enhancement of grain yield potential, and poor unloading into
caryopsis may be the possible cause of low stem NSC translocation, poor grain
filling and yield formation in R201.
