Respiration of maleic hydrazide treated and untreated onion bulbs during storage

Respiration rates were determined at a range of temperatures on onion bulbs cv. Rijnsburger sampled from a cool-stored bulk over a period of 8 months. In the first 5 months of storage, respiration rates were low and showed a small increase with temperature. During this period there was little or no difference between untreated bulbs and those treated with maleic hydrazide (MH) prior to harvest. Subsequently there was a rise in respiration rates, which preceded sprouting, but this was not evident in MH-treated bulbs. A relationship between respiration and dormancy was suggested by the correlation between respiration rate in January and sprouting in June for four cultivars.