/i / 7, r - ' / ,1 25, L90S U. S. DEPARTMENT OF AGRICULTURE, Bl REAU OF PLANT [NDUSTRY-Circular Kq. 11. B. T. GALLOWAY, Chief of Bureau. DANGER IX JUDGING COTTON VARIETIES BY LINT PERCENTAGES. O. K. (OOK. Bionomist in Charge of Bionomic Investigations of Tropical and Subtropical Pj w rs. ^ ^ **»» BUREAU OF PLANT INDUSTRY. Physiologist and Pathologist, and Chief of Bureau, Beverly T. Galloway. Physiologist and Pathologist, and Assistant Chief of Bureau, Albert F. Woods. Laboratory of Plant Pathology, Erwin F. Smith. Pathologist in Charge. Investigations of Diseases of Fruits, Morton B. Waite, Pathologist in Charge. Laboratory of Forest Pathology, Haven Metealf. Pathologist in Charge. Cotton and Truck Diseases and Plant Disease Survey, William A. Orton, Pathologist in Charge. Plant Life History Investigations, Walter T. Swingle, Physiologist in Charge. Cotton Breeding Investigations, Archibald D. Shamel and Daniel N. Shoemaker, Physiologists in Charge. Tobacco Investigations, Archibald D. Shamel, Wightman W. Garner, and Ernest H. Mathewson, in Charge. Corn Investigations, Charles P. Hartley. Physiologist in Charge. Alkali and Drought Resistant Plant Breeding Investigations, Thomas II. Kearney, Physiologist in Charge. Soil Bacteriology and Water Purification Investigations, Karl F. Kellerman, Physiologist in Charge. Bionomic Investigations of Tropical and Subtropical Plants, Orator F. Cook, Bionomist in Charge. Drug and Poisonous Plant Investigations and Tea Culture Investigations, Rodney II. True. Physiologist in Charge. Physical Laboratory, Lyman J. Briggs, Physicist in Charge. Crop Technology and Fiber Plant Investigations, Nathan A. Cobb, Crop Technologist in Charge. Taxonomic and Range Investigations, Frederick V. Coville, Botanist in Charge. Farm Management Investigations, William J. Spillman, Agriculturist in Charge. Grain Investigations, Mark Alfred Carleton. Cerealist in Charge. Arlington Experimental Farm, Lee C. Corbett, Horticulturist in Charge. Vegetable Testing Gardens, William \V. Tracy, sr., Superintendent. Sugar-Beet Investigations, Charles O. Townsend, Pathologist in Charge. Western Agricultural Extension Investigations, Carl S. Scofield, Agriculturist in Charge. Dry-Land Agriculture Investigations, E. Channing Chilcott, Agriculturist in ('harp'. Pomological Collections, flustavus B. Brackett, Pomologist in Charge. Field Investigations in Pomology. William A. Taylor and G. Harold Powell. Pomologists in Charge. Experimi ntal Gardt ns and Grounds. Edward M. Byrnes. Superintendent. Foreign Seed and Plant Introduction, David Fairchild, Agricultural Explorer in Charge. Forage Crop Investigations, Charles V. Piper. Agrostologist in Charge. Seed Laboratory. Edgar Brown, Botanist in Charge. Grain Standardization. John D. Shanahan, Crop Technologist in Charge. Subtropical Laboratory and Garden. Miami. Fla.. Ernst A. Bessey, Pathologist in Charge. Plant Introduction Garden, Chico, Cat, \Y. W. Tracy, jr.. Assistant Botanist in Charge. South Texas Gardt n. Brcm nsviUe, Tex., Edward ('. Green. Pomologist in Charge. Farmers' Cooperative Demonstration Work, Seaman A. Knapp, Special Agent in Chi Seed Distribution (directed by Chief of Bureau). Lisle Morrison. Assistant in General Charge. Editor. J. E. Rockwell. [Cir. 11] Chief Clerk, .lames E. Jones. 2 B. I\ I.-3S4. DANGER IN JUDGING COTTON VARIETIES BY LINT PERCENTAGES. INTRODUCTION. Many instances mighl be collected to show bow injudicious selec- tion can work injury to domesticated varieties of animals and plants. Too persistenl attention to a single character or standard often results in the Qeglecl of other indispensable qualities whose importance may remain unconsidered until some serious deficiency is revealed. Thus the coffee planter who selects for Large seeds without reference to other characters soon finds thai be lias in- creased the proportion of loose and irregular "beans," for these are frequently larger than any of the normal seeds. True improvements of varieties involve the preservation of high standards in manj directions at once. It may be allowable to spe- cialize on one desirable feature or another, hut none of the essentials can be safelj left out of account. The use of lint percentages as one of the primary standards in the selection of cotton varieties, and often as the single standard, is one of these dangerous tendencies which is likely to lead to injury rather than to improvement if cau- tion and discrimination are not learned from an appreciation of other factors. The danger of laying too much emphasis upon the percentage of lint is greatly increased by the practice common in some parts of the - it 1 1 of selling the seed cotton on the basis of the percentage of lint found in a tested sample of the crop. No scientific breeder would hold thai selection should be based on linl percentages alone, hut if the lint percentage continues to appeal- as the chief issue in the mind- of the farmer and of the commercial seed dealer much unin- tentional damage may be done. Inferior and unproductive varieties are likely to be planted if they have high percentages and actually superior varieties refused merel} because their percentages arc lower. Thus it has hern reported h\ Mr. William A. Orton thai an r. 11] 3 4 JUDGING COTTOK VARIETIES BY LINT PERCENTAGES. improved variety of Sea Island cotton Rivers . specially selected and distributed by the Bureau of Plant Industry of the United States Department of Agriculture, has failed to become popular because the lint percentage is slightly lower than in some other varieties, though in actual yield of lint it "compares favorably with any other."" It would be a serious misfortune if the buying and selling of un- ginned cotton on the basis of lint percentage should be the cause of extending this mistaken idea that lint percentage is all-important. Some of the State:- prohibit the sale of unginned cotton as a means of protecting farmers against thieves, hut the method of buying by lint percentage is in itself neither unjust nor inconvenient. It is essential, however, that the farmer, as well as the seedsman and the breeder, shall understand that lint percentages are being connected with two entirely separate problems. The use of the lint percentage to figure out the value of the commodity has nothing to do with the way the lint percentage should he used in determining the value of a variety. After the crop is ripe and the price is agreed upon the percentage of lint determine- what the farmer's returns shall be. This is the commercial problem. The agricultural problem comes before the crop is planted. It is to choose the variety which will give the most valuable product. Here the lint percentage is only one of several factors, for the highest percentage of lint does not insure the largest or the most valuable crop. The need of improving cotton varieties and method- of culture is appreciated now as never before, with the high prices of the fiber and the difficulty of securing labor to produce it. Planter and buyer alike are interested in improving the quality and increasing the yields. The time must soon come when intelligent farmers will carefully -elect their own seed, for experiment- are showing that larger yields and better staple can generally he secured in this way than by the frequent change of varieties, however promising the new stocks may have appeared in the place where they were bred. This makes it all the more important that farmers should not imagine that attention to lint percentages alone affords any assurance that a variety is being improved or that a new sort is superior to the best that their own neighborhood affords. The local adjustment of cotton varieties is a matter* of much greater practical importance than is generally supposed. Different conditions result in notable changes in the behavior of the plants. Even a superior variety may show a serious deterioration when planted for the first time in a new place. Improvements in yield ranging between 10 and 20 per cent have been found in the second • on, \Y. A. Sea Island Cotton, Fanners' Bulletin 302, I . S, Dept. of Agri- culture, p. 46. 1907. it] DGING COTTON VARIETIES BY LINT PERCENTAGES. .> generation over the adjacent rows representing the same stock planted in the Dew place for the (irsl time. The invasion of the boll weevil is leading to many changes in the methods of culture of cotton, and corresponding modifications <>( the standards of breeding arc also required. It is therefore especially important at this time to consider all the factors thai bear upon the quest ion of improvement. SMALLER OR LIGHTER SEEDS RAISE LINT PERCENTAGE. In using lint percentages for commercial purposes the size of the seed does Dot need to be considered, for the object is merely to calcu- late the amount of lint in a given quantity of seed cotton. When the lint percentage is u>n\ agriculturally as a basis for estimating the productiveness of a variety the size of the seed must he taken into ount, for the vaiuc percentage with a large seed means more fiber for the same number of seeds. If all ( otton plants produced an equal Dumber of seeds of the same size and weight the percentage of lint would be an index of the productiveness of a variety, but it is not safe to rely upon any sueh assumed equality, for the numbers, sizes, and weights of seeds are extremel) variable factors which change the significance of tin- per- centage. High percentages may accompany low yields or may result from small seeds. Smaller or lighter seeds increase the percentage of lint quite as effectively a- an additional amount of fiber. Larger seeds, on the contrary, reduce the percentage of lint in spite of the fad that the actual amount of lint in the boll may not he reduced. Reduction of the size of the seed raises the percentage of lint even though the libers do not become any longer and are not set an\ closer together. 'The area of the surface of the seed does not decline as rapidly as the weight of the seed. The surface is reduced in proportion to the square root of the diameter, the weight in proportion to the cube root . To increase the lint-bearing surface of a cotton seed by 3 per cent would involve an increase in weight of about 30 percent. The per- centage of increase of weight in the snu\ altogether outruns the increase in percentage of lint, and makes the iwrcentagi of lim smaller in spite of an increase in the amount of lint. Thus, if in a variety having :!•'! per cent of lint the weighl of the seed were in- creased by one-third the lint percentage would fall to about 26, even though the amount of lint were increased by ;! per cent, to cor- respond with the larger surface. Instances where the lint percentages show a notable decrease in spite ol actual additions to (he amount of lint are very common in in 6 JUDGING COTTON VARIETIES BY LINT PERCENTAGES. hybrids between cottons of the Sea Island type and some of the Mexican and Central American representatives of the Upland series. A Mexican cotton with 27 per cent of lint hybridized by Egyptian cotton having a somewhat higher percentage gave a progen}- with a percentage of only 22.9, although the lint increased in weight from 4.05 grams to 4.45 grams per hundred seeds. This addition to the lint was greatly outweighed, however, by the enlargement of the seeds from 10.95 to 14.75 grams per hundred. To make sure that a higher lint percentage is accompanied by an increased amount of lint it is necessary to know that the weight of the seeds has not declined, either by reduction in size or by change of texture or compactness. ADVANTAGE OF LARGE SEEDS AND LARGE-SEEDED VARIETIES. The size of the seed is a question of practical importance apart from the question of lint. In former decades small seeds would have appeared preferable, at least as a means of reducing the expense of picking and handling. The increasing demand for cotton seed for oil and other uses tends to reduce this preference for small seeds. During the last season cotton seed was nearly worth the picking, even without the lint. The prices of cotton seed need not go much higher before large-seeded varieties will be directly preferred. The presence of the boll weevil gives large seeds a definite advan- tage, since they contribute to the prompt development of the cotton by giving the young plant a better start. The stronger the young plant is at the time of germination the greater are its chances of breaking through the crust of sun-baked earth which weak seedlings are often unable to penetrate. Small-seeded varieties, like the Peter- kin, sometimes fail to come up, while large-seeded types, like the Russell, may show a good stand under the same conditions. An instance is related by Mr. L. H. Dewey, of the Bureau of Plant Indus- try, of a planter who selected his cotton for high lint percentage and small seed until the seedlings were too weak to come up. After germination the ability of the young seedlings to make con- tinuous growth must still depend considerably upon their size and the amount of stored nutriment contained in their tissues. The faster they grow at first the farther their roots will reach down into the moist soil and the less becomes the danger of being dried up or broken down by the wind. The more vigorous the seedlings the earlier the varieties should be, if other things are equal. Some of the early varieties, like the King, have small seeds, as they also have small bolls and short lint. The planting of such varieties has been advocated in boll weevil districts as a means of securing early crops. Nevertheless, it has to be considered that this form of earliness, secured by reducing the size and thus shortening the period [Cir. 11J JUDGING COTTON VARIETIES BY LINT PERCENTAGES. i of development, ma\ afford no better protection against the weevils than can be obtained in some of the large-seeded big-boll varieties. Earh opening of the bolls i- nol the best index of the amount of protection obtained l>\ early development. Long before the bolls are mature thej are beyond the reach of weevil injury. A variety which sets a crop of bolls early and carries them past the danger of weevil infection may produce a larger crop in the presence of the weevils than the variety which ripens the first bolls. Some of the Central American varieties of cotton retain the mature bolls for lon<_ r periods and do not open them until dry weather comes. The ideal babit of earliness would he met 1>\ a variety which could develop a large Dumber of bolls pasl the point of weevil injury earbj in the -en- son. Delay in the date of opening might he an advantage if all the hull- would open together and thus avoid the need of making several pickings <>( t he same field. 'Phi- plan of developing weevil resistance in big-boll cottons is worth} of careful consideration for the further reason that it avoids the injury to the industry which i- involved in extending the cultiva- tion of the small-seeded, short-staple varieties on the ground of earli- ness. Misapprehension regarding the importance of lint percentages tend- to conceal the true value of desirable big-boll varieties, both those now known in Texas and the other more definitely weevil- resistanl types now being introduced and acclimatized from Mexico and Central America. The big-boll varieties also have large seeds, so that the lint percentages do not represent their true value in com- parison with small-seeded varieties. This should not he taken to mean that the big-boll varieties have lower percentages than other type-. h>r both the Texan ami the Central American big-boll types often -linu very high percentages. The point is that a high per- centage in a large-seeded big-boll cotton should mean more, even as a percentage, than in a small-seeded small-boiled variety. For the reasons already indicated, the lint has to he relatively more abundant in a large-seeded variety to indicate even the same percentage as in a small-seeded variety. Thus it appear- that too much reliance upon lint percentages as a standard for judging varieties ha- t em led to keep us from fully appre- ciating the value of the big-boll varieties. In Texas, at least, the inadequate supply of labor make- the large bolls a very desirable feat ure. for t he cot ton can be picked much more readily and cheaply. Picker- are often willing to gather big-boll cotton at a lower price than the small-boll varieties, for the difference in the size of the bolls make- considerable difference in the proceed- of a daj '- labor. When labor is scarce the farmers who are unwilling to pay a higher price for picking small-boll varieties sometime- leave their cotton unfathered in the fields. [CIr. 11] 8 JUDGING COTTON VARIETIES BY LINT PERCENTAGES. ADVANTAGES OF HEAVY SEEDS. That cotton is no exception to other crops in the superiority of firm, heavy seeds has been demonstrated b} 7- a series of experiments made by Dr. II. J. Webber and Mr. E. B. Boykin, of the Bureau of Plant Industry, in South Carolina. The heavy seeds planted sepa- rately gave crops about 10 per cent greater than the light seeds. In Upland cotton the fuzz interferes with the separation of the light and heavy seed b} r winnowing, but it was found that this could be obvi- ated by rolling the seeds in a revolving drum with small quantities of paste, to stick the fuzz together and render the seeds easily sepa- rable. Deterioration in the texture, weight, and vitality of the seeds is one of the frequent symptoms of degeneracy in plants. The seeds are the young plants themselves. By weighing and other tests of the seeds we can learn in advance whether the inclosed plants are healthy and vigorous or malformed and puny. The vigor of the seed is of much more importance in afield crop than in garden plants which can be given special protection in their earlier stages. The seeds of cotton plants in particular are unusually subject to injury and deterio- ration, and the young seedlings are very delicate, as the farmer learns from the frequent need of replanting. The seed coats are not very strong. As in many other tropical plants the embryo of cotton is very large and is only loosely rolled up, quite unlike the seeds of mosi of the species native in the Temperate Zone. Unless the seed is sheltered and kept dry freezing readily kills it. HIGHER LINT PERCENTAGES WITH DIMINISHED FERTILITY. If two cotton plants bear the same number of bolls containing the same number of seeds, the plant with the higher percentage of lint might still produce less cotton than the other. The lint percentage does not express an absolute fact, but shows only a relation between the lint and the seed which may or may not be an indication of greater fertility. Even though the seeds were large and the lint per- centage still remained high, the number of bolls might be reduced and thus counteract the advantage of the increased amount of lint on the individual seeds. Lint percentages can not be substituted for actual tests of yield. When the productiveness of a variety or strain of cotton has been fairly and thoroughly tested, these results must replace any opini ns that may have been formed from lint percentages. There is no virtue at all in lint percentage standing alone. Attention to lint percent: es serves only to avoid one form of deterioration, as a partial substitute a Webber, II. .1.. and Boykin, E. B. The Advantages of Planting Heavy Cotton I, Farmers' Bulletin 285, U. S. Depa of Agriculture. 1907. [Cir. 11 I JUDGING COTTON VARIETIES BY LINT PERCENTAGES. 9 for tests nf yield, and even then they may be misleading unless the weight of the seed is also taken into account. To secure higher percentages of lint on seeds of the same size and weight means thai the fibers have to be longer, or coarser, or closer together. Experiments have shown thai longer lint means, almosl invariably, reduced percentages. Coarser lint is not desired, so that the crowding of the lint closer together would he the real objecl of selection for higher percentages. But whatever the character upon which selections are based, narrow breeding to secure very high degrees of expression of particular characters carries with it the genera] result of diminished fertility. To reduce the fertility of a variety l>\ careful selection for high per- centages would he in accord with the usual result of diminished fer- tility in highlj specialized, narrowly selected types. Selection by lint ntages instead of increasing the agricultural value of a variety might actually diminish it. The value of the variety mighl go stead- ily downward while the lint percentage was advancing. Thus, higher percentages of lint are not only unreliable as indications of increased production bul aught even accompany declining yields in degener- ating variel ies. If the -election began with a variety having a tendency to larger amounts of lint, selection might he followed by a further increase of the character, hut a careful and persistent selection might he expected to bring the other factor- of small or light srvA and reduced fertility into operation. Domesticated varieties usually degenerate much more readily than they advance to higher standards. To specialize our varieties of held crops in characters which have no practical importance i- not only a waste of effort but may actually injure them. LARGE YIELDS WITHOUT HIGH PERCENTAGES. It mighl lie argued thai plant- could produce more seed- if the seeds were smaller and that more lint could he secured from varieties with smaller seeds and higher percentages. It is true that the same amount of seed material made up into small seeds would produce more lint-bearing surface than if made up into larger seeds, h does not follow, however, that this method of increasing the lint accord- with the physiological economy of the plant. A- vet we have no evidence that varieties can lie improved in yield by reducing the -ceils and thus securing the higher percentages that result from the smaller -i/.e. That there is no necessary connection between lint percentages and yields is shown by the fact that very high yields are obtain d from varieties with relatively low percentages of lint. In Sea Island ami Egyptian cottons the percentages fall below those reached in some of our Upland varieties, hut huh yields are not prevented l>v [Cir. 11] 10 JUDGING COTTON VARIETIES BY LINT PERCENTAGES. lower percentages of lint. It is well known that the yields of cotton obtained in Egypt range distinctly higher than in the United States. Similar results have now been obtained in experiments with Egyp- tian cotton in the United States conducted by Mr. T. H. Kearney, of the Bureau of Plant Industry. After several years of acclimati- zation and selection at Yuma, Ariz., the Egyptian cotton is showing its normal fertility. It yielded in 1907 at the rate of 3,330 pounds of seed cotton per acre, more than any of the Upland varieties in- cluded in the test. The yield of lint was slightly exceeded by one of the Upland varieties, but the value of the lint of the Egyptian cotton was much greater than that of the Upland. The results of many tests of Upland varieties at the experiment stations of several of the Southern States have been tabulated by Mr. Fred. J. Tyler, of the Bureau of Plant Industry, who finds that the highest yields are secured from varieties with the higher per- centages of lint, as might be expected from the fact that the improved varieties have generally been selected with reference to the per- centage of lint. At the same time it is evident from the figures that there is no very direct or necessary relation between lint percentage and yield, for some of the notably prolific varieties show only mod- erately high percentages of lint. Thus, the Russell variety has an excellent reputation as a yielder of large crops of lint, though its percentage is only 32. Another even more striking instance has come to light in a recently published report of the Department of Agriculture of North Carolina. The results of tests of 27 varieties are tabulated separately with refer- ence to several different factors. The variety which gave the best returns for the farmer and was first in actual amount of lint stood as No. 13 in percentage of lint. The variety with the highest percentage of lint stood as No. 20 in yield of lint and in agri- cultural value. The high percentage of lint was not connected with greater fertility, but was evidently a consequence of the small size of seeds. The variety which produced the most lint ranked as No. 3 in size of seeds, while the variety with the highest lint percent- age fell to No. 23 in size of seed; finally, it was the latest in ripening of the whole series of varieties." Other things being equal, the high-percentage varieties would always yield more lint, hut it is evident that the other things are often unequal and that the high percentages have no fixed connec- tion with vigor and fertility. Tint percentage is important as long as the other features are not left out of account, hut persistent selec- tion for lint percentage alone would he as likely to reduce the crop as to increase it. a Bulletin of the North Carolina Department of Agriculture, vol. 29, No. -. p. IT. February, L908. [Cir. n 1 JUDGING COTTON VARIETIES B^ l.i.\i PERCENTAGES. 11 HIGH QUALITY WITH LOW PERCENTAGES. If high-linl percentages do Dot insure high yields, much less do the) insure high quality. With longer lint the percentage might be expected to rise, but the change is almost invariably in the oppo- site direction. In spite of the greater length, the percentage falls rapidbj as the lint of carefully selected varieties becomes longer. Longer lint, even in Upland varieties, is usually accompanied by ii deficiency of fuzz, as though the long lint were being attained by an approach to the characters of the Sea [sland and Egyptian types, where the seeds are lefl smooth and naked after the lint is removed. As the In/./, is weighed with the seed the absence of fuzz reduces the weight of the seed and tends to increase the percentage of lint. Nevertheless, the rule is that the lint percentage declines with even increase in the length of lint and smoothness of seed. Differences in the size- of the seeds would affect these results and would have to he taken into account in an\ efforl t" determine the true relation of the reduced percentage to the actual yield of lint. If the seeds were becoming larger, the reduced percentage of lint might not involve a reduction in yield, while if the seeds were be- coming smaller, the yield might decline even more rapidly than the percentage would indicate. Very high quality and very high percentages being apparently incompatible characters, the raising of percentages must he recog- nized a- a secondary consideration when high quality is seriously desired. With sufficient differences in price, low percentages of lint, even if they involve smaller crops, may still leave an advantage for the farmer. High grades of cotton are more than ever in demand. The time must soon conic when the question of quality will secure more careful consideration in all parts of the cotton belt. It is true that there are still many districts where the individual farmer can secure little or no advantage from improving the quality of hi- crop. 'The local buyer may refuse to pa\ a higher price 1" individual farmer- who gro'w better staple-, especially if only a few hale- are to he hail and the locality i- not known in the trade as producing a superior quality of cotton. Conceited action in a whole community or district is a- important in the choice of varieties a- in the application of measures of protection againsl the boll weevil, [f -Mine of the farmers carelessly continue the planting of inferior varieties' the whole district suffers, just as careless farmer- may keep their neighbors supplied with boll weevils instead of contrib- uting an honest -hare of effort toward mitigating the pest. A.sso ciations of cotton planter- are giving such matter- their attention, the importance of concerted action being more and more appreciated. m 12 JUDGING COTTON VARIETIES BY LINT PERCENTAGES. TRUE STANDARD OF YIELD IN COTTON. The fact which would give the mosl direct indication of pro- ductiveness is not the proportion between the lint and the seed, but the proportion of the lint to the plant as a whole. Comparison of the weight of the lint with the weight of the plant would deter- mine how much in the way of other tissues the plant has formed in producing a given amount of lint. It shows how efficient the plant is in producing lint. Such percentages of lint to dry weight of whole plants are not always easy to secure, because many of the leaves may fall before all of the bolls are mature. Even without weighing the plants itispossible by mere inspection in t lie held to judge something of their productive efficiency. The total yield of the individual plant is not a completely satis- factory index of the productiveness of the variety under field con- ditions if the plants are disproportionately large. The yield per acre may not be increased by larger individual production if the num- ber of plants is reduced. No method of judging individual plants can be accepted as a complete substitute lor actual held tests. There should he no discrimination against small plants if they are fertile in proportion to their size. If plants are small they can grow- closer together. Small plants have a distinct advantage in weevil resistance, for they can mature a larger proportion of the crop early iu the season, before the weevils become sufficiently numerous to prevent the development of the buds and bolls. Prompt production often has another advantage in the drier regions of the Southwestern States, where cotton cultivation is now making rapid advances, partly because of the prevailing high prices of cotton and partly because the holl weevil does less damage than in the humid regions nearer to the Gulf of Mexico. A small early type of cotton may he able to make prompt use of the available supply of water in the soil and thus mature a crop, whereas a large late variety may fail through drought to reach a productive maturity. A LINT INDEX FOR JUDGING VARIETIES. Since the lint percentage alone is not a suitable standard forjudg- ing varieties, the question nat u rally arises whether any other standard would better serve the purposes for which the lint percentage is now- employed. In the work of securing improved strains of cotton by selection it is very important that tin- breeder have as good a means as possible of judging in advance whether the plants that appear desirable in other respects can also he expected to excel in pro- duct iveness. It is commonly recognized that the yields of individual plants, single rows, or small plots arc not t rustworthy indications of out-turn [Cir. 11 I DGING COTTON VARIETIES BY LINT PERCENTAGES. 1 'A in the field, and it is often supposed thai the lint percentage repre- sents something more definite and reliable. [laving recognized the er that high lint percentages arc likely to be accompanied by small seeds and small bolls, we must seek the most practicable means iif avoiding these dangers b) basing our judgment on some [ess equivocal standard. Though nothing short of actual Held tests will determine the productiveness of a variety and its adaptation to local conditions, it is entirely possible to avoid some of the uncertain- of lint percentages by using as a lint index the weight of the lint itself instead of the less important proportion between the lint and the seeds. The lint from 100 seeds of Upland cottons ranges in weight from t> grams or [ess to 9 grams and upw ard, ami t hese figures can be directly applied as a standard in judging varieties in place of the lint per centages. A lint index on this basis would mean something actually accomplished. The unintentional discrimination in favor of small seeds and small bolls would be avoided. The lint index would give the breeder a far better assurance of superiority than the percentage cou hi ever afford. Reducing the size or weighl of the seed would no t give a variety the misleading advantage that it does by Increasing the lint percentage. The chances are fair that the largest amounts of lint will be found on seeds of large size, if not on the largest. At the same time large seeds would not he admitted if the amount of lint were small. The relation between large seeds and large amounts of lint (high lint index' has been toted h\ Mr. I ). X . Shoemaker, of the Bureau of Plant Industry, by a study of weights of seeds and lint in a series of selections of Triumph cotton. This \ariet\ is very well adapted for such study because it represents one of the most uniform types of I [pland cot ton. The weights of 73 samples were used for comparison. The avei weight of Kit) seeds was 12.37 grams, and the average weight of lint of inn seeds was 7.38 grams. Of II plants whose lint was above the average only 4 plants fell below the average in weighl of seed. Simi- larly, of 29 plants which fell below the average in weight of lint only 4 were above the average in weight of seed and these exceeded the average only a little. No such evidence of correlation was found when the same data were arranged with reference to size of -ceil and percentage of lint. Of the 28 plants which showed lint percentages above the average of :!7.7. about hal lad seeds below the aver- weight, while the other 13 had seeds above the avert) The -election of the plant with the liighest percentage of lint i t2.8) would have meant the rejection of no less than II plant- whose seeds produced larger amount- of lint. In other words, the plant with the [Cir.ll] 14 JUDGING COTTON VARIETIES BY LINT PERCENTAGES- highest percentage would have ranked as number 42 in the series of ?:! plants if arranged by lint indexes. The plant with the highest percentage of lint really had only seven-eighths as much lint on its seeds as the plant that showed the highest lint index. Tins serves to indicate the extent of the practical difference in this variety between the lint index and the lint percentage as the basis of selection. If all the plants were like that with the largest percentage of lint, the crop would be one-eighth smaller than if they were all like that with the highest lint index, provided, of course, that both produced the same numbers of seeds. The only objection to the use of lint indexes instead of the lint percentages is that, the labor of determining the indexes is somewhat greater, though it is no more than would always be required to avoid the danger of preferring inferior stocks because of high percentages. The counting and weighing of 100 seeds after ginning is a simple matter. The additional difficulty would come in counting seeds while the lint is still on them, and then in ginning these small quan- tities separately and at the same time with sufficient accuracy to make the results of value. The lint percentage affords a means of avoiding this difficulty with- out lessening the accuracy of the results, for the weight of the fiber of 100 seeds can easily be calculated after the weight of the seeds and the lint percentage are known. The weight of the hundred seeds divided by the percentage of seed gives the weight of the hundred seeds before ginning. Subtracting the weight of the ginned seeds gives the lint index or weight of the lint of the hundred seeds. With a slide rule it is easier to multiply the weight of the seed by the lint percentage and then divide by the percentage of seed. The lint percentage is made more reliable by using large samples the seeds of which do not need to be counted, for the percentage is a matter of weight alone. Thus the percentage still remains of use to the breeder, though no longer employed by itself as a standard for judging varieties. The index has a direct relation to the size of the seed which the percentage alone does not have. Lint indexes determined in this way can be still further corrected or combined with the results of other tests of productiveness, such as the amount of lint from 10 bolls or the amount of lint yielded by a whole plant. Nevertheless, there is not tin 1 same need of such cor- rections as when the percentage was used directly as a standard. The number of seeds in a lock of cotton appears to he much more constant than the number of locks in a boll, so that 10-boll samples are likely to be much more subject to variation than the lint indexes unless care lie taken or allowances made for differences in the number of locks and in the number of seeds in the locks. [Cir. II I .11 l",i.\ 1 i<>_\ VARIETIES i:V UN I PERCENTAGES. 15 The following table illustrates the range of diversitj of linl indexes and percentages in differenl varieties and types of cotton. The lasl two columns shov the differences of rank which resull from tlu>, substitution of the lint index for the lint percentage. Tabli I / am pies of lint indexes of different varieties of cotton compared with lint i ntages. Weight Lint index III of lint oflOO seeds . Lint per- cenl - lo of lint to seed cotton.) Hank by Rank by Rank by age. Gram*. (iriimx. P( r ct nl. 11.33 1 1 (I - 9. 14 7 2 2 13. 12 - • 8 3 4 13.97 8.00 6 4 7 10.00 7.50 12 3 14 5 1 11.26 7.28 39. 3 13 6 3 i i 33. 7 5 7 10 U.62 12 8 8 16. in • 3 9 15 18.20 5.43 23 o 2 10 17 • .-. 17 • 19 11 11.58 5.13 11 12 11 4.90 15 13 11 4. 16 35. 3 20 14 9 14 62 4 15 is • 30.8 17 16 13 i 31.5 is 17 12 21.3 9 is 19 U 5 16 19 16 12.53 15.1 10 20 23 1.39 18 6 21 21 1.11 is 3 22 22 21 .81 16. 1 23 23 22 CONCLUSIONS. The currenl opinion thai a biigher percentage of lint proves the superiority of a variety of cotton is a dangerous error, more likeh to load to the deterioration of cotton varieties than to improvement. High lint percentages give no assurance of large yields or of bigh quality, but ma\ resull from smaller or lighter seeds and -may char- acterize weak or unproductive varieties. Other features which bring increased productiveness or bigher quality may more than compen- sate for lower linl percentages and should have the impartial consid- eral ion of the farmer and breeder. The fact that linl percentages are used by buyers to estimate the amount of lint in a crop of cotton affords no reason why the farmer or the breeder should consider the lint percentage as the chief require- ment. The custom of selling cotton by percentage of lint should not establish in the mind of the farmer the idea thai the lint percentage is a true standard forjudging varieties for planting. The agricultural question of how to produce the most fiber to the acre is entireh sepa- rate from the commercial question of calculating the amount ol lint in the crop after the seed cotton bas been harvested. I fir. 11 | < — (O a W X ^^^™* ir> o o» LL ^— ^^ CO LL == CM o ^^^^ O) > ^^^^ CD H _^_ O n ^^^ CM ex to ^j CM > *"^~» r- =