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Time of harvest and seed quality in lupins

P.B. Goodwin1, E. Corbin2, I. Barua3, A.A. Adegbite1 and J. Lynbury4

1Department of Agronomy and Horticultural Science, University of Sydney, N.S.W. 2006.
Agricultural Research Station, Condoblin.
Present address: B.A.D.C., Krishi Bhavan. Dacca-2, Bangladesh.
Agricultural Research Institute. Wagga Wagga.

Farmers in NSW have had some difficulty in producing consistently high quality lupin seed lots. We have been attempting to define the optimum time to harvest. Trials were conducted with Lupinus angustifolius at the University Farm, Camden in 1976, and at Wagga Wagga in 1977 and 1978. Optimum seed quality in hand harvested seed occurs at a fairly sharply defined stage, close to the time of maximum dry weight, when the seed moisture content varies between 10% and 50%. depending on the order (Table 1). It coincides with the time that 100% of the embryos become yellow. After this stage there is a slow (dry conditions - less than 3% per week) or more rapid (wet conditions - up to 15% per week) loss in seed viability.

TABLE 1. Development of seed quality in Unicrop lupins at Wagga in 1977 (adapted from Barua, 1978).

In machine harvested seed the picture is rather different. Seed is badly bruised at moisture contents above about 15%, and optimum seed quality is obtained by harvesting as soon as the moisture content of the highest seed order making a major contribution to yield falls below 14%. If machine harvest is delayed until the moisture content of this order seed falls below 12%, then there is likely to be loss in yield due to pod drop, and seed quality is reduced, probably due to increased mechanical damage.

Barua. I.N. (1978). M.Agr. Thesis. University of Sydney.

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