Differential Longevity of Castor (Ricinus communis L.) Germplasm Conserved Under Uncontrolled Storage Conditions Across Extended Periods

Abstract

Castor researchers and seed producers mostly store seed under uncontrolled conditions. The ability of castor (Ricinus communis L.) seed to remain viable across extended periods of storage under such conditions has not been widely investigated, although this is an important issue for maintaining seed lots. Seed longevity of 2,961 castor accessions stored for <1–19 years under ambient conditions was investigated to know how castor seed loses vigor in long-term storage and to determine the genetic variability for seed longevity. The results showed that castor seed retained 40% germination even after 19 years of storage, and no accession lost germination completely up to four years of storage under ambient conditions. All the accessions maintained 100% germination for one year, but from second year onwards differential germination percentage (10%–100%) was observed among accessions stored for the same duration; some accessions stored for 11–14 years maintained 80%–100% germination, whereas some stored for three years had <50% germination. Therefore, we concluded that it would be safe to store seed of any castor genotype for one year after harvest under ambient conditions, but beyond that the genotypic response needs to be considered for maintaining high germination percentage (80%–100%). The information generated would be useful to researchers and seed producers in properly maintaining seed lots.

KEYWORDS:

• castor seed
• genetic variation
• germination
• oil content
• seed weight