Cauliflower (Brassica oleracea L.) seed vigour: imbibition effects
1990
McCormac, A.C. | Keefe, P.D.
By means of a machine vision facility, the process of water-imbibition in a small seeded brassica species was recorded as the visible increase in seed volume. Dry cauliflower seed (Brassica oleracea) showed an immediate rapid phase of imbibition upon the addition of water. This initial phase was associated with the reduction in seedling root growth resulting from the imbibition of cold water, and the rate of uptake of water at 20 degrees C was negatively correlated with subsequent seedling growth. Damage to the testa of dry seed resulted in an increased rate of imbibition and a corresponding decrease in seedling root growth measured on slant boards. This showed that the intact testa of cauliflower seed is capable of acting as a barrier to water influx and that a high rate of water uptake is damaging to the embryo. Testa damage reduced percentage soil emergence of seeds, as did raising the soil moisture content during the imbibition period by watering immediately after sowing. Both these treatments were believed to increase imbibition rate. Conditions which encouraged a low rate of water uptake also improved the rate and uniformity of emergence. Correlation of mean imbibition rates (measured in a laboratory test) with soil-emergence indicated that the sensitivity to imbibition damage varied between seed lots and interacted with the absolute rate of water influx to determine the final percentage emergence. This factor prevented reliable prediction of seedling performance from the ranked-order of measured imbibition rates. The significance of these findings to the seed production and modular transplant raising industries is discussed.
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