Integrated Cultural Production Methods for Maximum Okra Seed Yields
PROJECT BACKGROUND AND GOAL
Soybean Cyst Nematode (SCN) is a very costly disease problem for soybean producers in the Midwest. Okra (Abelmuschus esculentus) is not a host for SCN and wouldn’t build up the SCN populations. I became interested in okra seed production for use as an oilseed a couple of years ago after observing its amazing growth rate in the garden. I did some research and found it wasn’t a host for SCN and is sometimes used as an edible oil and protein source instead of harvested prematurely for the green pod as it is in this country. I sent a sample of seed to the NCAUR, USDA-ARS lab in Peoria for analysis. Ron Hosler conducted the lab work and found the seed was 21% crude oil and 25% crude protein. The oil is 69% unsaturated with a fatty acid composition as follows: 53% linoleic, 16% oleic, 2.7% stearic, 27% palmitic and a trace amount of C14. This oil would be very suitable to cooking and salad oil.
Okra has been traditionally raised as a fresh vegetable instead of allowing it to mature for seed production. Okra is a very growthy plant and I want to find out its true potential for seed production. Little is know about how to manage okra for seed production. I want to investigate the different cultural aspects of production to find what is the best for seed production. Okra is not a legume so it does not fixate nitrogen, so some will need to be applied to it. One of my experiments will investigate what rate will be optimum. Wide rows and relatively low populations are used in vegetable production of okra to facilitate hand harvest of the pods. I want to try higher populations and closer row spacings to increase seed production. Okra is a warm season plant and is not commonly grown in the Midwest. It grows very slowly in cool weather. A planting date experiment with three planting dates will study the effect of planting date on seed yield. Okra is an indeterminant plant, so the longer the season, potentially the larger the seed yield. I have done some preliminary research with producing okra seed and had yields up to 3000 pounds of dry seed per acre. I found this yield somewhat respectable as plant population and weed control were less than perfect. I feel that okra has a higher potential for seed production than I have observed so far.
Ultimately, I want to find the optimum cultural methods for seed production and show that okra can be a viable crop for the Midwest.
I set up three small scale experiments which were randomized and replicated four times: a nitrogen rate experiment with five different nitrogen rates: 0, 60, 120, 180, and 240 lbs of N; a planting date experiment with three planting dates: May 17, June 7, and June 28; and a population/row spacing experiment with 4 populations and 2 row spacings. I also had a field scale experiment with okra versus soybeans.
The plots were hand weeded and notes were taken periodically. The plots were all planted on May 17 with the exception of the planting date experiment. Clemson spineless was the variety used. The plots were over planted as okra has a tendency to be hard seeded and has uneven germination. The plots were then hand thinned to a desired population of 80,000, at least that is what the plan was…Rhizoctonia infected the okra and thinned the stand to below the target population and most of the research had to be scratched. The rhizoctonia also has a permanent affect on the okra plants, basically it plugs up the vascular system similar to the way cholesterol plugs our arteries. This causes the okra to grow sluggishly and some plants died midseason. The infection was variable across the plots and it had a greater affect on yields than any of the treatments. Dry weather stress at planting caused this infection and the later planted okra did not have the symptoms.
I planted the later okra at a depth of 3 inches to help avoid the drought stress. The okra came fine from this depth and had no symptoms of the disease. I will be able to salvage some data from the planting date experiment. Modern seed treatments might have controlled this disease. I did experience some stalk borer damage later in the season.
I am currently waiting on a weigh wagon to help with the harvest of the field scale experiment and waiting on some lab work to be completed on the small scale samples. The field scale okra had less rhizoctonia in it and I predict it to yield around 3000 to 4000 lbs of seed an acre based on seed count sampling. The second planting date appears to be the highest yielding of the planting dates, but this is because of the absence of disease rather than the planting date. These seed samples are also being tested for crude protein levels which will show the suitability of okra to be planted as a double crop behind wheat. The last planting [June 28] made some seed but I am concerned about the maturation of all the seed. I know there is some immature seed and a commercial combine would blow most of these light seeds out.
I learned that okra is very susceptible to rhizoctonia and that okra can emerge from great planting depths. I attribute this to the hard seed coat that protects the seed from breaking when emerging. Okra has several mechanisms that allow it to survive and produce seed in drought conditions: large taproot system for extracting moisture and nutrients from greater depths; indeterminant growth nature that allows the plant’s reproductive stage to be spread over a longer time period and that all of the seed yield does not have to be filled at one time and that the okra can go completely dormant if conditions are very harsh and come back and produce seed when it rains. These properties have broadened my horizon on the suitability of okra as an oilseed crop
WORK PLAN FOR 2006
I plan to repeat the same experiments fro next year and do what I can to avoid infection from rhizoctonia by planting deeper or waiting for a rain if necessary. I may also use a stale seed bed system to conserve moisture. I have also applied for the Illinois Department of Agriculture Conservation 2006 grant. I am using this grant to get some much needed lab work done on the okra seed. I plan to take a large amount of seed to the NCAUR lab in Peoria where Dr. Roque Evangelista will prepare the seed and press the oil from the seed. The oil will then be refined and data taken. The goal is to produce 100 gallons of oil and this oil could be distributed among various potential end users. I am also taking seed to the Illinois Crop Improvement lab where John McKinney will do a variety of tests that will help determine okra’s usage as a protein source, a tofu source and an “okra milk” source. Okra flour may prove to be a very useful high protein food stuff.
I hosted a filed day on August 10. Local farmers were the main attendees along with some ag professionals. There were about 20 people in attendance. It was very hot that day and I believe it scared several people off. Dan Anderson interviewed me and wrote a short article in the University of Illinois publication “AGRO-ECOLOGY News and Perspectives,” Fall 2005 issue about my okra project. He plans to write more when I get more data. I plan to continue having field days and may write an article or two myself for SARE publications. I also plan on working with local high schools and John Wood Community College if they are interested in a presentation and/or field tour. I may attend and make a presentation at the NCR-SARE National Convention in Wisconsin next summer if my proposal is accepted and if my schedule allows it.