North Dakota State University -- NDSU Agriculture Communication
7 Morrill Hall, Fargo ND, 58105-5655, Tel: 701-231-7881, Fax: 701-231-7044
agcomm@ndsuext.nodak.edu

March 15, 2001

Seeding Rate For Conlon Barley

Last spring (2000) Conlon was approved as a malting barley, the first two-rowed barley approved for production in North Dakota. Interest in this two-rowed barley variety has increased dramatically since then.

"Seed supplies of Conlon have become a major issue," says Mike Peel, North Dakota State University extension agronomist. "Obviously many producers want to know how low of a seeding rate they can use and still get an acceptable yield."

The best seeding rate is the one that will achieve an optimum plant population, Peel says. The recommended plant population for barley is 1.25 million plants per acre. A typical six-rowed variety like Robust will have 13,000 to 14,000 seeds per pound. To achieve the recommended population would require 89 to 93 lbs per acre. Seeding rates also must be adjusted for germination. If this seed lot had a 95 percent germination rate, the final seeding rate should be at 94 to 98 lb per acre or about two bushels per acre.

Two-rowed barley has much larger seed than six-rowed but Conlon has a large seed even for a two-rowed variety, Peel notes. Conlon will typically range from 9,400 to 10,000 seeds per pound. Peel emphasizes that these figures are averages. Always determine the number of seeds per pound on your seed lot as seed size among seed lots varies considerably. To achieve a plant population of 1.25 million plants per acre of Conlon with a seed size of 10,000 seeds per pound and a germination of 96 percent you will need to plant 130 lbs. per acre or about 2.7 bushels per acre.

"Thatís a lot of seed, especially when seed is expensive and supplies are short," notes Peel. "Data from NDSUís North Central Research Extension Center in Minot indicates that a plant population of a million plants per acre of two-rowed barley will produce nearly as well. This would reduce the seeding rate to about 2 bushels per acre."

The research raises the question, "How low can my seeding rate be while still achieving an acceptable crop yield?" There are several factors that should be considered. Planting rate data from Minot indicates that as seeding rates drop from 1.5 to 0.5 million plants per acre yield drops by about 15 percent. With an average yield of 70 bushels per acre, this is a loss of 10 bushels per acre. This is when the crop is planted on time.

A crop planted at a reduced rate has to compensate for the reduced stand through tillering, Peel explains. If conditions are favorable for tillering, a cool period with adequate moisture following planting, then the reduced seeding rate will have less impact. The longer the cool period, the more tillering will take place. If conditions are unfavorable because of late planting or hot and dry weather, then less tillering will take place and the impact on yield will be larger.

"The planting date is crucial," says Peel. "If a two-rowed crop of barley was planted in late April or early May the reduction in yield will probably not exceed the 15 percent range but this will change dramatically as the planting date is moved later. A sparsely seeded barley crop planted on May 25, in most years, has very little chance to tiller and would be expected to have a dramatically lower yield."

Plant stand is important for weed management. Higher planting rates are encouraged to ensure a healthy uniform stand that will be more competitive with weeds.

Planting rate also impacts crop maturity. As planting rates are reduced maturity is delayed. A two-rowed barley crop planted at one bushel per acre will probably mature two days later than one planted at two bushels per acre. Although thatís not likely to be a large concern, if stands are spotty as is more likely with lower seeding rates, crop maturity will be less uniform.

When seed is limited, as is the case with Conlon, a producer must determine what his desired out come is. The highest yields, and most uniform crop, are achieved with higher seeding rates. By the same token, the highest yield per seed planted occurs at lower seeding rates. It would not be advisable to seed at rates lower than one bushel per acre. Also, it is important to consider the impact seeding rate will have on quality. As plant populations are reduced the variability in seed size will increase.

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Source: Michael D. Peel, (701) 231-8037, mpeel@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, Richard_Mattern@ndsu.nodak.edu