Rice is not cultivated in Eritrea because of its high water requirements and arid to semiarid conditions. However, most agricultural watersheds in Eritrea are associated with >80% non-agricultural lands, which produce significant runoff that can be diverted for use by rice crop. Experiments were conducted at Hamelmalo Agricultural College, Eritrea, using four NERICA rice varieties viz. N1, N4, N10 and N11 under rainfed (Io) and limited supplementary irrigations (I) in 3 replications. Results showed that plants were taller under limited irrigations than rainfed. Among the 4 varieties, N11 was most affected by water stress in which plant height was 0.72 m under rainfed and 0.89 m under limited irrigations. Effective tillers were highest (6) in N11 under limited irrigations and lowest (2) in N10 under rainfed. Panicles were shorter (0.20 m) in N10 and longer (0.23-0.24 m) in N1 and N11. Irrigations delayed maturity by 6-15 days. Water use by N11 was higher both under limited irrigations (987 mm) and rainfed (477 mm) and lower by N10 under rainfed (457 mm). Root growth in all the varieties was better under irrigations (I) than rainfed (Io). Roots were limited to 0.7 m depth under rainfed (Io) but grew down to 0.8 m in N1, N4 and N11 under limited irrigations (I). Roots in N10 were limited to 0.5 m depth under Io and 0.7 m under I. More than 63% roots in N10 were in 0-0.1 m layer under rainfed as against less than 55% under limited irrigations. In lower layers, roots under Io were more in N4 than others, which is a beneficial trait for better performance under semiarid environments. Roots in N11 were better and uniformly distributed in lower layers under irrigated conditions. Rooting patterns and grain yields showed that N11 was most responsive to irrigations but susceptible to water stress and N4 was best under rainfed followed by N10. N4 was next to N11 under irrigated conditions.