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 Essay - jan/feb 2004
Appearance, Perceptions and
Reality - II
James C. Delouche
Professor Emeritus Mississippi State University
One of my first scientific papers published in 1957 reported on the use of pre-chill, surgical and alternating temperature treatments for releasing seed dormancy in Poa pratensis and Agropyron smithii. Since light had some effects on the release of dormancy in both species but was not a treatment in my experiments, I felt that I should state clearly in the Methods and Materials section that light was excluded from the time of planting until the percentage of germinated seeds was determined. So, I ended the section with a sentence I thought was an adequate description of the methods used, viz., "All of the experiments reported in this paper were carried out in darkness." During the next 10 years or so I received more than 15 letters and several phone calls from readers of the paper inquiring, a few seriously but most is jest, just how I was able to carry out research in the dark. One professional friend exclaimed, "I know you are a fantastic seed technologist and a man of considerable nocturnal exploits but I had no idea you were equipped with the night vision of a bat!"
Confusion of Cause and Effect
Most scientific faux pas do not turn out so innocently and humorously as the one related above. Some introduce error into the scientific database, i.e., literature, that is perpetuated, extended to other phenomena, and generates additional errors. Two examples follow.
In the early 1960s an article was published in a University magazine entitled, " Color tells the Difference." In "popular" style it reported that researchers had determined that the dark brown seeds in a population of Medicago sativa seeds were not viable and concluded that the pigments that produced the brown color of the seed coat caused deterioration and death of the seed. It happened that at the time we were studying seed deterioration in several closely related Trifolium spp. and had data showing that the color of the seed coat could be changed from the natural tan to brown by storage under warm, humid conditions, improper and inadequate aeration after harvest, and insufficient cleaning to remove leaves and other green matter from the seed mass. Some of the brown seeds were dead, some produced weak and/or abnormal seedlings, but others were fully viable and germinated normally. Furthermore, we were able to effect the color change in the seed coat by simply soaking the seeds in water for several hours followed by air drying without any apparent effect on viability. We concluded that the change in seed coat color was an effect of exposure of the seeds to environmental conditions that resulted in deterioration of the seeds and loss of viability and not the cause. We noted with satisfaction that when the researchers at the other University published their findings in a scientific journal there was no mention of "toxic" effects of the seed coat pigments on viability. The seed coat color change was described as an effect of seed deterioration and not a cause.
The significance of elevated levels of free fatty acids in cotton seed has been the subject of a much more widespread confusion of cause and effect. It has long been known that cotton seeds exposed to frequent rain, warm temperatures and other "weathering" conditions before harvest and/or that "heat" in storage because of inadequate aeration are low in germination and vigor and high in "free fatty acids." Determination of the percentage of free fatty acids is an integral part of the quality assurance and control system of every major cotton seed producer. Seeds with more than 1.5 % free fatty acids are usually diverted to the oil mill rather that saved for seeds. Many persons knowledgeable about cotton seed quality believed, and some still do, that the accumulation of free fatty acids causes loss of germination and recommended that the cotton breeders select for low free fat acidity. It has also been long known, however, that many dead cotton seeds are very low in free fatty acids and that is some cases seed lots high in free fatty acids are also high in germination and vigor. Free fatty acids are produced by the breakdown of lipids in the storage tissue of cotton seed during severe weathering in the field before harvest or heating of cotton seed in the storehouse. The conditions that cause breakdown of the lipids in the seed also cause the fundamental physiological and biochemical changes involved in loss of viability and vigor. Thus, the increase of free fatty acids in cotton seeds is an effect of deteriorative processes and not their cause.
Invalid Assumptions
Invalid assumptions and/ or faulty logic are frequent causes of erroneous conclusions in research. A paper published in the 1960s concluded that dormancy in rice seeds was caused by the hulls. The main evidence for the conclusion was that germination of dormant seeds was greatly increased by hulling the seeds, i.e., removing the lemma, palea and subtending glumes. I showed the paper to one of our graduate students and suggested that she try the hulling treatment. She did and informed me that hulling did not significantly increase germination. I assumed she must have made an error so I removed the hulls of some of the same seeds and planted them for germination. Germination increased from 9 % for the control to 57 % for the hulled seeds. I shared my results with the student and suggested she repeat the hulling treatment. She did but again found essentially no effect of hulling. We then sat side-by-side at the laboratory bench and hulled seeds from the same lot at the same time and she planted both sets. Her set of hulled seeds did not germinate better than the control while germination of the set I hulled increased by more than 50 %. Something was wrong and during the next several days we determined that the critical factor was how carefully the hulls were removed. The lady student's small fingers, sharp fingernails and delicate touch removed the hulls without scratching the pericarp, while my large fingers and clumsy manipulations resulted in many scratches and abrasions of the pericarp. When the student scratched the pericarp near the embryo with a needle after hulling seeds, germination was nearly 100 %. We then devised a simple surgical treatments to prove that the hulls were not critically involved in rice seed dormancy. A very small section of the lemma was excised (removed) just above the embryo for 1000 seeds; 500 of the seeds were planted for germination without further treatment while for the other 500 seeds, a needle was inserted through the hole in the lemma to puncture the pericarp. The punctured seeds all germinated while the seeds not punctured did not germinate higher than the control. Since only about 4 % of the hulls, i.e., lemma, was removed in making the hole, the hulls could be involved in the dormant condition. The pericarp was the critical structure. We published our results and conclusions but for many years there were references in the literature to the hulls of rice as the cause of seed dormancy.
The conclusions I reached in an investigation I did rather early in my career resulted in my greatest professional embarrassment. A farmer filed a complaint that the maize seed he purchased and planted emerged very poorly although labeled 95 % germination, while neighbor farmers obtained excellent seedling populations from plantings made at the same time. I was assigned to investigate the complaint and observed that emergence was indeed very poor - less than one seedling per meter. I talked to the neighbor farmers and confirmed that they had no problems with emergence from plantings at the same time and under the same conditions. So, I concluded that the farmer's complaint was justified, that the seeds were mislabeled for germination and reported my conclusions to the Chief Seed Control Inspector. The farmer retained a lawyer to prepare and file a civil suit for damages against the seed company. About a week later the Chief Inspector asked me to accompany him on a return visit to the complainant's farm. He walked around in the field, looked at the neighbors' fields and began to dig in the row deeper and deeper until he found a band of maize seeds at about 20 cm. Some of the seeds had rotted but many had produced a rudimentary root and very stubby plumule that was decaying. Further investigation revealed that the laborer the farmer hired to plant the maize was neither trustworthy nor experienced and had set the planter at the maximum depth of about 20 cm. The farmer and Chief Inspector pronounced some harsh comments about my competence and commonsense and the lawyer threatened to sue me for incompetence, negligence and wasting his time. I apologized profusely and humbly to everyone, again and again and, thereafter, I have rigorously refrained from reaching hasty, uninformed conclusions based on superficial analysis and invalid assumptions.
Every day we are besieged by sophisticated and increasingly hostile rhetoric in support of the various views and sides of the important political, social, economic and scientific issues of these times. Although sophisticated the rhetoric is replete with invalid assumptions, faulty logic, much confusion of causes, effects and consequences, and blatant falsehoods. There are many issues, many sides and much rhetoric in our areas of agriculture, seed breeding, production and marketing. Somehow and in some way we must sort through this rhetoric for the factual information essential for making rational decisions on the views we should accept and the sides of issues we need to support.
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