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Bean seed quality in Burdekin crops: effect of time and method of harvest

G. Somerset, MD. Abdus Siddique and P.B. Goodwin

Department of Agronomy and Horticultural Science. University of Sydney, N.S.W. 2006.

The Australian bean seed growing industry occasionally produces poor quality seeds. There is a lack of knowledge of the development of seed vigour and of the factors responsible for causing specific seed faults. The present paper evaluates a number of procedures for handling the crop prior to threshing under Burdekin growing conditions.

Five methods of handling the crop (treatments; Table 1) were evaluated using the variety Canyon in the upper Burdekin Valley during the 1978 growing season. The treatments were each tested at seven stages of crop development (Table 1) where stage 1 corresponded to 96% green: 4% yellow pods, and stage 7 was 100% dry pods. For treatments 2 to 5, seed was hand threshed once the plants were dry enough to machine harvest. The ungraded seed was germinated in sand/peat mix in shallow trays. The percentage normal seedlings is shown in Table 1.

TABLE 1. Percentage normal seedlings out of the total of all seed harvested.

The treatments in which the seeds dried inside the pods (treatments 2, 3, 4 and 5) produced well filled seeds of good quality, even when the treatments were given at the green pod stage. However. there was a reduction in seed size and an increase in the number of discarded seeds when the treatments were applied at an early stage of seed development. Stage 5 was the optimum time for all of the treatments except the immediate threshing treatment. At this stage about one-third of the pods were dry, one-third yellow-fleshy to brown and one-third green to yellowish green; and the fresh and dry weights of the seeds were at their peaks. Windrowing (treatment 4) at this stage of crop development seems to be the most suitable practical way of handling the crop to produce high quality seed.

In a parallel study on the effect of windrow size, using Gallatin 50, windrows of 5 or 10 rows to 1 were found to be superior to larger or smaller windrows for the production of high quality seed.

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