A mechanical planter was developed to sow seed of baby lima beans (Phaseolus lunatus) in small plots. The mechanical seeder allowed small plots to be quickly and consistently seeded at a fixed spacing. Seeds were manually spread along a 10-ft (3.0 m) base plate containing 50 holes of slightly larger diameter than the seed length and at the desired seed spacing [2.4 inches (6 cm)]. Once all the holes were filled, a slider plate below the base plate containing holes of the same diameter and spacing, but which were slightly offset, was slid horizontally so that the holes of the base and slider plates aligned and the seeds dropped to the bottom of the furrow. Compared to manual planting, the mechanical planter increased the precision of seed placement and reduced the time needed to plant 50 seeds. The planter was easy to use and transport, and was inexpensive.
Prior studies have demonstrated that a Gaspardo vacuum seeder provides less uniform seed spacing than a Stanhay belt seeder. It was hypothesized that the difference was primarily because of the greater seed drop height on the Gaspardo seeder. A Gaspardo metering unit was modified by adding a slide or an enclosed tube to guide the seeds from the release point (seed plate) to 1.0 inch (25 mm) above the bottom of the seed furrow. Seed uniformity tests were conducted with cabbage (Brassica oleracea), onion (Allium cepa), and mustard (Brassica juncea) seeds. The modified planter unit was compared with an unmodified unit. No improvement in seeding uniformity was noted with either the slide or the tube. In fact, seed placement uniformity was degraded with the addition of the slide and tube. Although it is probable that the seed spacing nonuniformity was caused by drop height, attempts to control the seed trajectory were unsuccessful.
Seedlings are established in small growing containers to reduce cost of greenhouse space, while improving crop uniformity. These seedlings often are referred to as plugs. Vacuum seeders are used by larger growers to seed many flats per season (Bakos, 1983); however, individual growers, producing plants for their own use, may not be able to justify expensive seeding equipment. Several moderately priced vacuum seeders are available (Bartok, 1988). They consist of a metal tray with small drilled holes to hold the seed in place when a vacuum is applied to the tray from an external source. However, several problems with them exist. Seeds must be free of extraneous materials that might clog the small holes. A slight jarring of the plate, especially when the plate is turned upside down over the seed flat, may cause seeds to dislodge, resulting in unplanted cells in each flat. Also, different sizes of seeds and flats require completely different seeding plates and plate holders. A small grower may choose to seed flats by hand by placing seeds individually in each cell. This is feasible only for large-sized seeds or with pelleted seed. A simple, inexpensive, non-vacuum alternative design is presented and evaluated.
Seed deterioration is expressed as the loss of quality, viability, and vigor during aging. Several comprehensive reviews have identified free radical-mediated lipid peroxidation, enzyme inactivation or protein degradation, disruption of cellular
Kansas Agricultural Experiment Station contribution no. 93-197-J. We thank Sharp Bros. Seed Co., Healy, Kan., for providing seed. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations