Dual Grading in Rice Bean (Vigna umbellata [Thunb.] Ohwi and H Ohashi).

Grading is an important post-harvest operation where the seeds are homogenized based on size, weight and color to upgrade the quality of the seeds. Rice bean is one of the underutilized crops with hidden multipurpose utility. Hence, studies were carried out to upgrade the quality of seeds through sequential dual grading using size and color of the seeds. The seeds were size-graded using BSS 5 × 5, 6 × 6 and 7 × 7 wire mesh sieves and each of the size grades was further graded based on color as yellowish green, light brown and brown and were evaluated for the seed and seedling quality characters. The results revealed that the seeds size-graded using BSS 5 × 5 recorded the maximum seed quality characters in terms of germination and vigor, but it was on a par with BSS 6 × 6 which recorded the maximum recovery. Further, grading based on the color revealed that yellowish green seeds of both BSS 5 × 5 and 6 × 6 sieve recorded the highest germination of 90%, though the recovery was only 10 and 8%. Hence in rice bean, this type of dual grading could be adopted for nuclear and breeder seed production where seeds are to be with higher initial quality. But for commercial seed production both yellowish green and light brown seeds retained in grade BSS 6 × 6 (includes BSS 5 × 5 retained sieve) could be selected as the recovery of seed would be more than 80% combined with seed quality characters which were higher with these dual grading. [ABSTRACT FROM AUTHOR]