The influence of temperature and humidity in storage on seed viability and hard-seededness in the west Australian, Blue Lupin, Lupinus digitatus Forsk

Abstract

Freshly harvested seeds of L. digitatus were stored for up to 11 months at all combinations of six constant temperatures and five constant relative humidities. Testing for hard-seededness was by soaking in water at 15°C, and for viability by emergence tests in seed boxes. Permeability was found to be governed by seed moisture content. All seeds with more than 14 per cent. moisture (wet weight basis) remained fully permeable. Below 14 per cent., permeability decreased with decreasing moisture content until at 11 per cent. all seeds were virtually impermeable. Impermeability was readily reversible under humid conditions down to 12 per cent. moisture content, but practically irreversible below 9 per cent. Softening of semi-hard seeds took place no more rapidly at 94 per cent. R.H. than at 76 per cent. Seed which was air-drying in the laboratory remained fully soft for about 1 week after harvest, and thereafter hardened only slowly. Seed which had been kept permeable for 12 months hardened at the same rate. Viability was impaired by both high moisture content and high temperature.