Abstract:
Increasing rice yield potential is essential to secure world food supply. The quantitative
trait locus qTSN4 was reported to achieve yield increases by enhancing both source and
sink capacity. Three greenhouse experiments and one field experiment in the Philippines
were conducted to study near-isogenic lines (NILs) in two genetic backgrounds,
subjected to treatments with restricted light resources through shading (greenhouse)
or population density (field and greenhouse). A consistent promotion of flag leaf width,
leaf area and panicle size in terms of spikelet number was observed in the presence of
qTSN4, regardless of environment. However, grain production per plant was enhanced
only in one greenhouse experiment. An in-depth study demonstrated that increased
flag leaf size in the presence of qTSN4 was associated with increased photosynthetic
rates, along with lower SLA and greater N content per leaf weight and per area.
This was emphasized under low light situation as the qTSN4-NILs did not express
shade acclimation traits in contrast with the recipient varieties. The authors conclude
that qTSN4 is a promising subject for further physiological studies, particularly under
limited radiation. However, the QTL alone may not be a reliable source of increased
yield potential because its effects at the plant and population scale are prone to
genotype environment interactions and the increased panicle size is compensated
by the adaptive plasticity of other morphological traits
