Head rice yield, mixed variety for width and chalkiness of perennial rice as affected by variety and multiple harvest in irrigated conditions.

To ensure the effective adoption of some newly introduce perennial rice varieties in Cote d'Ivoire, the effect of multiple harvests [(Initial harvest-S0), (first ratoon harvest-S1), (second ratoon harvest-S2), and third ratoon harvest-S3)] and perennial rice varieties [(PR101, PR107, PR23, PR24, PR25 and WITA-9 as check)] on head rice yield (HRY), mixed variety for width (MVW) and chalkiness (CH) were investigated in irrigated conditions.S0 recorded the lowest HRY (39%) among all the harvests, whereas S1 and S3 recorded the highest and similar HRY (54% and 52% respectively) followed by S2 (47%). S0 recorded high MVW (34%), while S1 and S2 recorded similar and moderate MVW (27% and 26% respectively) and S3 recorded the lowest MVW (21%). This implies that grain shape becomes uniform with increasing number of harvests. S0 recorded the lowest CH (20%) followed by S1 (23%), S2 (27%) while S3 recorded the highest CH (30%). This implies that grain chalkiness increases with increasing number of harvests. On average over all the harvests, WITA 9 recorded the highest HRY (53%) and lowest MVW (3.8%). PR23 and PR25 recorded the lowest CH (9 and 10% respectively). PR101 recorded the lowest HRY and highest CH while PR24, PR23 and PR25 recorded the highest MVW (43%, 43% and 41% respectively). There was significant interaction between variety and multiple harvest on all three traits. PR23 and PR25 in S1 had higher and similar HRY (63% and 64% respectively) than WITA 9. WITA 9 consistently had the lowest MVW in all the harvests (4%). PR107, PR23, PR25 and PR24 had lower CH in S0 (0.4%, 6%, 8% and 12% respectively) than WITA 9 (18%). In conclusion, multiple harvests (S0 to S3) increased HRY and chalkiness while decreasing variation in grain width. The reasons for changes in HRY, CH and MVW are not known in this study, and further research is needed to identify factors affecting variation in these traits in multiple harvests. Significant interaction between variety and multiple harvest for the traits studied suggests that it is necessary for breeders to evaluate grain quality traits of rice varieties in each harvest time in perennial rice cropping system variety screening.