Abstract:To study stem non-structural carbohydrate (NSC) accumulation and translocation from stems to grains in rice genotypes with various sink capacity,127 recombinant inbred lines derived from the cross of Zhenshan 97 × Minghui 63 were planted under field conditions in two years.NSC concentrations and accumulations in stems at three stages (30 days after transplanting,heading date,and maturity),leaf area,diameter and number of vascular bundles in peduncle,and grain yield were investigated.There were large genotypic variations of sink capacity among lines ranging from 289.4 g/m2 to 945.4 g/m2.Based on sink capacity,all lines were clustered into 6 types including mean sink capacity of 388.0(A type),575.3(B type),667.3(C type),728.4(D type),793.4(E type),and 887.2 (F type) g/m2.NSC concentrations and accumulations of the six types at heading stage were significantly higher than those at 30 days of transplanting and maturity.NSC concentrations and accumulations of the types with small sink capacity (A and B types) were generally higher than those of the ones with large sink capacity at 30 days of transplanting.However,they were lower at maturity.At heading stage,the types with large sink capacity had higher NSC accumulations than those with small sink capacity,in spite of insignificant difference in the NSC concentrations.Types with large sink capacity had generally more vascular bundles in peduncle and low source:sink ratio (leaf area per unit sink capacity).Changes in NSC concentrations during the duration from 30 days after transplanting to heading were not significant between the six types.Changes in NSC accumulations increased with the increase of sink capacity.As sink capacity increased,the apparent transferred mass of NSC (ATMNSC) increased.However,the apparent contribution of transferred NSC to grain yield (ACNSC) declined first and increased later.ACNSC was higher for types with large sink capacity,which may be due to the large NSC accumulation before heading.The large ATMNSC during grain filling,the more stem vascular bundles,and the low source:sink ratio.Considering relatively small leaf area per unit sink capacity for types with large sink capacity,increasing leaf area and stem NSC accumulation as source for yield formation might be an approach to obtain high grain yield for genotypes with large sink capacity.