Lodging resistance locus prl5 improves physical strength of the lower plant part under different conditions of fertilization in rice ( Oryza sativa L.)

Abstract

High fertilizer application rates increase grain yield and biomass in rice, but reduces lodging resistance. Lodging resistance locus prl5 enhances pushing resistance through delaying leaf senescence and increasing carbohydrate reaccumulation in stems. This study demonstrates the effects of prl5 under different levels of Nitrogen·Phosphorus·Potassium basal fertilizer application using a chromosome segment substitution line based on the genetic background of Koshihikari, which contains prl5. High fertilizer application rates enhanced pushing resistance of the lower part, but did not consistently affect the pushing resistance of the whole plant. Independent of fertilizer application rates, prl5 enhanced pushing resistances of both the lower part and the whole plants. Plant height, biomass and grain yield were increased by high fertilizer application rates, but stem diameter and the dry weight of basal culms did not show consistent increases as determined over a period of 2 years. In leaves just after heading, chlorophyll (Chl) contents, rather than Rubisco contents, were correlated with fertilizer application rates. At the fully ripe stage, fertilizer application did not affect Chl and Rubisco contents in leaves, while prl5 increased the contents in the second leaf. High fertilizer application rates did not affect the concentration of non-structural carbohydrates (NSCs) in basal culms, but prl5 increased them at the fully ripe stage. These results suggest that fertilizer application reduces lodging resistance by highly elevating the center of gravity, but that prl5 can counteract this effect by enhancing the physical strength of the lower part through delaying leaf senescence and increasing NSC reaccumulation in culms without any effects of different fertilizer application rates.