By Dr. John E. Baylor Director of Market Development Beachley-Hardy Seed Company Dr. John E. Baylor Director of Market Development Beachley-Hardy Seed Co. Recent questions on hard seeds in legumes has prompted me to do a column on the subject. Frankly, the whole matter of hard seeds is complex. Hopefully, however, the following may help all of us to better understand what hard seeds are, and their role in agriculture. Seeds that do not absorb water when placed in wet or moist sur roundings, because of an imper meable seed coat, are referred to as hard seeds. In Held crop seeds, the largest number of hard seeds are found in small seeded legumes such as alfalfa, red clover, birds foot trefoil, and crownvetch. Hard seeds in general are viable or live seeds, and normally over time, do ITABO - DELTA - MILWAUKEE - PORTER CABLE - RYOBI - EMGLO - DIEHL - POITRAS -OEWALT - FREUD - MAKIT, Delta Quality-Built Save s236°° I o _J o UJ Ui * 3 Distributors of Supplies and Machines for For Your Convenionce Metal & Woodworking Industries We Sell Pulleys, V-Belts, Sprockets & Chain - And We Are Open Thurs. Evening Til 8:00 P.M. Store Hours: Mon., Tues., Wed., Frl. 7:30-5:00; Thurs. - 7:30-8:00; Sat. - 8:00-12:00 MMVH - onaud - nVM3O - SVailOd ■ IH3IQ • 01DH3 - I9OAH - 318VO U3J.ua germinate. However, because they do not take up water immediately when exposed to moisture, they are considered dormant or hard. What Causes Hard Seeds? Technically, “hardseededness” is credited to an impermeable lay er either on or just under the sur face of the seed, and while hard seededness is a generally charac teristic of most small seeded legumes, there are differences among species and among variet ies within species. Among the clovers, for example, ranked from high to low, species differ in their degree of resistance to becoming permeable as follows; white, ladi no, alsike, red, crimson. Thus, hard seeds of red clover would become permeable and germinate sooner than hard seeds of white, The Delta Saw Now $529 00 BLUE BAIL MACHINE CO., QIC. Call: Terry, Sylvan. Marty Ken, Larry or Aaron (717) 354-4478 Blue Ball, PA 17506 ladino, or alsike. And, while spe cific data are not available, I would expect hard seeds of red clover to also germinate sooner than those of alfalfa. Speaking of alfalfa, we know that some varieties regularly deve lop more hard seeds than other varieties. On the other hand, the same variety grown in different fields may show wide differences in hard-seed content. Environmental conditions under which the seed is grown are a major factor determining the percentage of hard seeds and the degree of hardseededness, with temperature during and immedi ately following maturity playing a major role. For example, hard seed percentages of 40 to 50 per cent are common in alfalfa seed lots grown in Washington and other northwestern stales, while alfalfa seed lots of the same varie ty grown in California seldom have more than a 20 to 30 percent hard-seed content. The imperme able layer is formed late in the seed development process. Thus, if growth is stopped abruptly, the impermeable layer may have lim ited time to develop fully. Like wise, drying of the seed, both in the field and in storage, seems to play an important part in the deve lopment of hardseededness. The temperature and humidity of seed storage facilities also have a pronounced effect on hard seededness. High relative humidi ty during seed storage reduces, and in some legumes, prevents :27” table ion wings >aclty R or L of blade • Lifetime-lubricated ball bearing construc tion • Jet Lock self aligning rip fence • See-thru blade guard • Up-front controls • UL listed SEE THIS BAG VAL UE TODAY! Includee I'A Single Phese *62-042 Motor • aaxnvMHW ■ vnaa ■ oavi! formation of hardseededness that occurs in storage at low humidity. In the past, as much as 20 to 30 percent hard seed in legumes was thought to be advantageous in the event of poor or unfavorable weather conditions following planting, and this level is still con sidered okay under some conditions. However, with alfalfa, at least most seedsmen prefer no more than 10 percent hard seed. Recent studies do indicate that with alfal fa late germinating seeds cannot compete well with established seedlings and new plants make only a minor contribution to improving stands. This would not be as true with red clover. Regard less, many authorities still feel that for most legume species, hard seeds can be, and are, very benefi cial for filling in where old plants disappear. The three most frequently used commercial methods to lower hardseededness are storage, blending, and scarification. As suggested earlier, normal storage from harvest to planting time will reduce hard seed percentages, although the exact results are unpredictable. Blending seed lots of the same variety produced in different areas is a common method of providing seed to the consumer with fewer hard seeds. If necessary, the number of hard SALE ENDS NOV. 30, 1988 JJJvSrJJ Lancaster Farming Saturday, November 12,1988-Dl3 How Is Hardseededness Reduced? 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Many other methods to decrease hardseededness have been investigated by researchers, and for species where hard seeds are a special problem, special techniques to reduce hard seeds can be and have been used by the seed industry. However, because of the risks involved, we do not recommend scarification on the farm. Hard seeds in small seeded legumes are common, but the mechanisms involved are com plex. There are many factors that influence the percentage of hard seeds and the degree of hardness, and while excessive amounts of hard seeds, especially in alfalfa, may be a concern, we still feel that hard seeds can be, and are, very beneficial for filling in where old plants disappear. NOT L10N... THE CLASSIFIED LIVESTOCK SECTION HAS BEASTLY SELECTIONS! For