Dry Bean Production Systems for New Genetic Material with Upright Architecture
(Results from first year of a three year project)

Investigators: John A. Smith, Machinery Systems Engineer
C. Dean Yonts, Irrigation Engineer
Robert G. Wilson, Weed Specialist
University of Nebraska Panhandle Research and Extension Center

Objective: The overall objective is to determine if evolving dry edible bean varieties from new genetic background, particularly those with upright architecture, have greater potential in production systems utilizing narrower row spacing and higher plant populations. Specific objectives are:

1. Determine yield of an evolving, upright, variety compared to a conventional variety of the same class, when planted in a production system with narrow rows, high plant population, and intensive management.
2. Determine if species or quantity of weeds change with these production systems.
3. Examine appropriate weed control strategy for narrow row, high plant population production systems.

Background

Many of the dry edible bean varieties currently being developed, including Great Northern and pinto classes, have determinate, upright type architecture. The primary incentive for this "open" plant type is improved disease resistance. The question that must be asked is: Can the maximum yield potential of this type of plant be realized within the conventional production system of wide rows and low plant populations? Or, would this genetic material be more profitable for the grower in a system with very narrow rows, high plant populations, and intensive pest management? Soybeans perhaps offer some similarities, with the simultaneous movement from bush plant types in wide rows to upright plant types in narrow rows and high plant populations.

This issue involves not only yield, but the total integrated system of irrigation, weed control, disease control, fertility, planting, and harvest. Before a producer should consider changing the production system or these individual production components, there must be documented yield or production cost advantages. An increasing number of growers in other production regions, including Michigan and Canada, are using upright varieties of several classes of dry beans in narrow row-high plant population systems and are convinced this is the future direction for their circumstances. We must evaluate these production concepts in Nebraska to keep Nebraska's dry bean industry competitive.

Procedure

The plot area was located at the University of Nebraska Panhandle Research and Extension Center near Scottsbluff, NE. The soil type is a very fine sandy loam with a pH of 8.0 and 1.0% organic matter. The area had been cropped to corn harvested for forage in 1998. The area had been deep ripped in the fall of 1998 and roller harrowed in the spring of 1999. Eptam-Lasso herbicide was applied to the plot area and incorporated into the soil with a roller harrow prior to planting.

The 1999 study included nine production systems - all eight combinations of two plant types, two plant populations, and two row spacings, plus one additional system. The two plant types were Pinto Vison, a newer, more upright variety, and Pinto BillZ, a more tractional, semi-vine variety. The two target plant populations were 60,000 and 120,000 plants/A. The two row spacings were 7 ½ and 30 inches. A ninth system used Vision variety, 120,000 plants/A, and 7 ½ inch row spacing. All treatments were replicated five times in a RCB statistical design. Each plot was 30 ft wide by 60ft long with a border of at least 10 ft on all sides of each plot.

The top 2-3 in. of soil was allowed to dry thoroughly before planting to minimize potential soil compaction where a tractor tire would run over a planted row or where a row would be planted in a tire track. The plots were planted on June 10, 1999 with a Deere ME 2 pneumatic planter with the flat plate and doubles eliminator seed meter option to achieve good seed spacing. The tractor was equipped with a "hitch shifter" that allowed the planter to be moved laterally up to 15 inch on the tractor. This feature allowed the tractor to follow its previous tracks and plant the 15 inch row spacing by making two passes without running over the row area. The 7 ½ inch row spacing plots were planted by making four passes through the same plot and running the tractor in the same tracks each time. Seed was planted 1 ½ inch deep and accurately spaced within the row to achieve the desired seeding rate. The seeding rate was increased 15% over the target plant population. The planter was equipped with a planter monitor to verify seeding rate for each plot.

The 30 inch row spacing treatments were cultivated two times for weed control. The 7 ½ and 15 inch row spacing treatments were sprayed with 1 ¾ pts of Basagran plus 1 qt/A crop oil on July 12, 1999 to control growing weeds. Asana at the rate of 4 oz/A was applied to all plots on July 13 to control Mexican bean beetle.

All plots were irrigated with a side roll sprinkler irrigation system. Irrigation schedule was based on soil moisture sampling.

Results
(These results are from only one year of data and must be considered "preliminary")

Plant population in each plot was measured on June 30, 1999. There were no statistical differences among row spacings or variety. Plant population averaged 63,000 plants/A for the low population and 120,000 for the high population treatments, averaged over all replications.

Crop growth was good during what might be considered a "normal" growing season. A light hail passed through the plot area when the plants were in the cotyledon stage with very minor injury. Plants in the plots with 7 ½ and 15 inch row spacing that had application of Basagran herbicide had noticeable stunting from the herbicide application. These plants appeared to be approximately 2 inches shorter in height than the plants in the 30 inch row plots for the remainder of the season. The plants in the BillZ plots had a noticeable presence of rust late in the season after pod fill was complete. We did not feel that pod set or pod fill was affected by the foliar disease, although seed size might have been affected. Plants in the Vision plots were substantially taller and more upright than the BillZ plants until the first week in September when a heavy rain, with wind, caused the Vision plants to tip over. Even after tipping over the Vision plants were more defined than the semi-vine BillZ plants.

Weeds of prevalent species were counted in all plots on September 8, 1999. The numbers of weeds were so low that there were no statistical differences in weed populations among the nine system treatments.

All bean plants in a sample area of 5 ft by 20 ft were hand pulled on September 30, 1999 and threshed with a Hege plot thresher on October 1, 1999. The BillZ plots matured and were ready to harvest approximately two weeks earlier than the Vision plots. All plots were pulled and threshed at the same time when seed in all plots was ready to thresh.

The variety Vision had statistically higher seed yield and larger seed size compared to the variety BillZ, when averaged over row spacings and plant populations (Table 1). The 7 ½ inch row spacing had higher seed yield than the 30 inch row spacing when averaged over varieties and plant populations, but there was no difference in seed size caused by row spacing (Table 2). Plant population did not contribute to differences in seed yield or seed size, when averaged over varieties and row spacings (Table 3). Caution: These results are from only one year of data. This study must be repeated for two more years before conclusions should be considered.

Table 1. Seed yield and seed size response to the two plant types (varieties) averaged over both plant populations and both row spacings.

Table 2. Seed yield and seed size response to the two row spacings averaged over both plant populations and both plant types (varieties).

Table 3. Seed yield and seed size response to the two plant populations averaged over both plant types (varieties) and both row spacings.