Storage Life of Illinois Bundleflower and Western Indigo Seed

Abstract

Seed of Illinois bundleflower (Desmanthus illinoensis (Michs.) MacM.) and western indigo (Indigofera miniata var. leptosepala (relative humidity were imbibed in a controlled environment for 20 Turdays with a night/day temperature regime of 15/25 degrees C and a 12-hour en stored for 1 to 4 years at 16 degrees C and 40% photoperiod. Preimbibition treatments included acid scar-ification by immersion in concentrated sulfuric acid for 15 minutes, mechanical scarification by cutting the seed coat at the end opposite the micropyle, and an untreated control. Seed viability was determined by a triphenyl tetrazolium chloride test. Germination rate and cumulative germination decreased for untreated Illinois bundleflower seed and increased for untreated western indigo seed as the length of storage increased from 1 to 4 years. The decrease in germinability of Illinois bundleflower seed was related to the development of an impermeable seed coat, while the increase in germinability of western indigo seed was related to a decease in hard seededness and the fulfillment of after-ripening requirements. Scarification treatments increased cumulative germination and germination rates in each seed storage class for both species. Over the 4-year storage period, Illinois bundleflower seed viability decreased by approximately 10%, and western indigo viability remained relatively constant.