I farm 200 acres in Pike County, Illinois and raise corn, soybean, wheat, milo and hay, currently I have no livestock. I have implemented soil conservation practices on my farm for several years and have enjoyed benefits of reduced soil erosion and increased tilth. Low grain and livestock prices occurred a few years ago and drastically reduced the profit margin of many farmers, myself included. I began to look at other potential sources of income and this is what prompted my interest in trying okra as an oilseed crop.
Project Description and Results
The goal of this project was to investigate okra’s potential of producing seed under drought conditions. Okra is a very resilient plant and observations made from previous research have shown the plant to survive in very stressful conditions. The plants have the ability to go dormant and fully recover once more favorable conditions return. I wanted to research the mechanisms the plant uses to fight stress and the effect stress has on seed yields.
The experiment would involve artificially inducing drought stress treatments on okra and soybean and reducing stress treatments by irrigating okra and soybean. Soybeans are being included in the study since they are also an oilseed and commonly grown across many regions of the United States. I am using the soybeans as a barometer of the environment and producers from many areas could get an idea of growth conditions. The drought inducement will be the result of planting the plot on a ridge of a low water holding capacity sandy soil with a CEC of about 12. A structure was build to deflect rainfall from harvest rows should rainfall occur during the critical period. The non-drought treatments were irrigated to relieve visual signs of drought stress. This location had previously been used for livestock so the fertility is very high and the irrigated crops could take advantage of that. The experiment was set up as a 2×2 factorial replicated four times in a randomized block design.
This was first planted in 2006 but was abandoned because of poor seed quality produced such low populations. It was too late in the season to replant. The experiment was repeated in 2007 with a different cultivar: Hastings Improved Perkins. This is an old open-pollinated variety that is similar to Clemson Spineless but is dwarf and can flower up to 10 days earlier.
The plot was hand planted at the end of May at rates much higher than the expected populations: 160,000 for the soybean and 80,000 for the okra. Nitrogen fertilizer was applied to the okra at a rate of 200 lbs per acre since it isn’t a legume and I didn’t want low fertility to have an effect on yields. I believe this rate to be higher than necessary. The plot was hand thinned twice and continuously hand weeded. I had some minor damage to the okra by prairie voles and an errant deer which knocked some plants over. Most of the season was hot and dry , both crops were affected by stress during the vegetative stage of development but I felt it was more important to focus on the reproductive period and delayed irrigating until then. The okra needed to be thinned a third time and by the time I realized this high population was causing over-competition between plants and excessive water usage. As a result flowering did not occur at Mid-July like I expected it too. I began irrigating the non-stress treatments on the 3rd of August and installed the rainwater diversions at that time. The diversions really weren’t necessary at this period due to dry weather, but you never know how quickly a storm can form during the peak of the summer. Drought stress was already present at this stage with both species showing symptoms. Growth rates of both species had slowed and the okra had begun to abort flower buds, the soybeans also lost flowers. The stress continued until August 16th , the okra had lost its leaves but was maturing its pods and the soybeans had dropped many pods and a few leaves, I felt the soybeans were within three days of complete death. The non-stress treatments quickly responded to the irrigation applications of 2/3 of an inch per day and grew quite rapidly. It was very evident that the irrigated treatments were going out yield the non-irrigated treatments.
On August 16th a powerful storm came through the area and destroyed my rain water diversion mechanisms and lodged the irrigated treatments. Two inches of natural precipitation was received that day including my drought treatments and effectively ended the experiment. The lodging was more severe in the okra plants and I tried unsuccessfully to stand them back up manually. Light interception was affected so much that the okra plants aborted up to 5 developing pods, I had never seen this happen before. The soybeans faired better and eventually stood back up after I assisted them. I did cease the irrigation treatments after the storm since light interception had been reduced and water was needed as much. The drought treatments began to recover after the rain, the soybeans responded quicker due to the fact they still had leaves on the plants. The okra did leaf out and re-bloomed but these later pods weren’t included in the harvest. I had intended to irrigate until the end of August as the peak of the reproductive period for both species would be over by this time. I believe the irrigated treatments would yield substantially more if I had been able to irrigate for the intended period. Both species were hand harvested in October, two 1/10,000th of an acre samples were taken from each row and oven dried to 0% moisture, the data has been extrapolated to pounds of dry weight per acre.
Okra irrigated treatment: 2618 lbs/acre
Okra drought treatment 923 lbs/acre
Soybean irrigated treatment 2053 lbs/acre
Soybean drought treatment 1287 lbs/acre
The irrigation treatment increased the seed yields of both species. I expected to see a dramatic yield increase due to irrigation and it was evident. The yield increase would have been even greater if I had been able to irrigate for the intended duration. The drought treated soybeans out yielded the drought treated okra; I believe this was due to the fact that the soybeans were able to recover so quickly when the storm destroyed the rainfall diversion mechanism. The soybeans still had some leaves remaining and were able to compensate from the low pod number by increasing seed size. The okra yields were also decreased from the delay in flowering; the plants could have been flowering and setting pods before the onset of drought stress. Water use efficiency was greatly affected by this delay in flowering as the plant grew vegetative and depleted moisture reserves in the soil rather than produce seed. I don’t know how much yield was lost, but I know it would have been substantial. As far as water use efficiency of the irrigated treatments, I can say that 8 and 2/3 of an inch of moisture was applied to these treatments and the subsequent differences in yields of the drought and irrigated treatments can be attributed to the irrigation. I am not an expert on irrigation and haven’t had any experience irrigating a commercial crop. I would encourage the input of others with more experience in area of irrigation to comment on the amount of gain/amount of water applied.
I do feel that the project was a success. I believe that I have more proof that okra can compete as a viable crop. I am disappointed of the problems caused by the poor quality seed in the 2006 attempt and the problems caused by weather in the 2007 attempt. However, I was able to glean some usable knowledge.