Relationship between Vertical Root Distribution and Yield Traits in IRRI's New Plant Type Rice

This experiment was conducted to elucidate the relationship between vertical distribution of rice roots and yield traits under yield conditions. Eight IRRl`s new plant type rices(NPTRs) were tested in a volcanic ash soil paddy field under dense (10 × 10 ㎝) and common (20×20 ㎝) planting densities. These lines were evaluated to have more spikelet numbers per panicle (SNP), lower filled grain rate (FGR), and lower rough grain weight per hill (RGWH). In dense planting, rough grain weight per stem (RGWS) was increased due to heavier culm and leaf dry weight (CLDW), and both RGWS and CLDW were related with the percentge of root distribution (%RWI) in the 10 ∼ 30 ㎝ soil laver, while in common planting. RGWS was not coosely related with CLDW. SNP was highly related with cool dry weight (RDW) in the 0∼10 ㎝ soil layer. FGK was mainly affected by RDW in the 10∼30 ㎝ soil layer under both planting densities. RGWS was positively correlated with top dry weight (TDW) and harvest index (HI), and TDW wes positively correlated with RWI under common planting or %RWI under dense planting, and III was positively correlated with RWI io the 10- 30 ㎝ soil layer only under dense planting. RGWS was closely related with root weight index by dry weight (RWI) in the 10∼30 ㎝ coil layer and %RWI in the 0∼30 ㎝ or 10∼30 ㎝ soil layer under dense planting, and with only KWI in the 10∼30 ㎝ mil layer under common planting. But RGWH showed the close positive relationship with RDW and KWI in the 10∼30 ㎝ soil layer under dense planting, while under common planting, il showed the close positive relationship with RWI and %RWI in the 10∼30 ㎝ soil layer %RWI in the 0∼30 ㎝ soil layer. The deeper root system in rice, especially under dense planting, is important for high yield of NPTRs focusing on the increment of top mass production and harvest index.