In situ sprouting and regulation of fresh-seed dormancy in Spanish type groundnut ( Arachis hypogaea L.)

Abstract

Two hundred groundnut ( Arachis hypogaea L.) germplasm accessions and 21 cultivars belonging to the Spanish group (ssp. fastigiata var. vulgaris) were screened for pod loss due to sprouting of seed in the field. Some cultivars were also tested for germination of the fresh-seed with or without testa and treated or untreated with ethrel or abscisic acid (ABA). Large variation in pod loss due to in situ sprouting of seed, and fresh-seed dormancy (FSD) was found among the accessions and cultivars. Fresh-seed dormancy index (FSDI) varied from 2% in Chico to 88% in ICGS 44 (the check with high FSD). Cultivars with an FSDI value of less than 10% showed more pod loss in situ than the cultivars with high FSDI. Thus pod loss due to in situ sprouting increased with a decrease in FSDI. Cultivar SB XI did not show any in situ sprouting or pod loss. A direct relationship ( r, 0.86 ∗∗) existed between fresh-seed germination of accession/cultivar in the laboratory and the percentage of its plants with sprouted seed in the field. Seed of two Spanish cultivars ICGS 11 (dormant) and GG 2 (non-dormant) when tested for germination after treatment with ethrel or ABA at various seed development stages showed different germination response to these chemicals. Seed of GG 2 showed up to 40% germination even at an early stage (S 1) of seed development, whereas the seed of ICGS 11 responded to the ethrel only at maturity (S 4). Regulation of FSD appeared to be more under the control of the testa than the cotyledons. The variation in the degree of in situ sprouting can be used for breeding Spanish cultivars with various desirable levels of FSD.