SOME FACTORS AFFECTING WATER ABSORPTION AND GERMINATION OF SEED CORN BY GEORGE HARLAN DUNGAN B. S. University of Illinois, 1917 THESIS Submitted in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE IN BOTANY IN THE GRADUATE SCHOOL OF THE UNIVERSITY OF ILLINOIS 1921 cu , tu CO \^l\ UNIVERSITY OF ILLINOIS W3\ THE GRADUATE SCHOOL 19 1 HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER MY SUPERVISION RY G eo rge Harlan Dung an ENTITLED Soma- Factors Ger mination of Seed Horn BE ACCEPTED AS FULFILLING THIS PART OF THE REQUIREMENTS FOR THE DEGREE OF Ma ster of Science Recommendation concurred in* Committee on Final Examination* *Required for doctor’s degree but not for master’s X? Ky ■■ rb> ft; _ - rg. ■ TABLE OF COII TEATS I. Introduction 1 II. Literature 3 III. Materials and Methods 7 ..... , 5 IV. Results 9 Influence of Stage of Harvesting Corn on Its- Water Absorption and Germination....... 9 Effect of Initial Moisture in Corn on Its Water Absorption and Germination... 13 Composition of the Corn Kernel and Its Water Absorption. .16 Two Types and Twp Varieties of Corn Soaked in Water at Constant Temperature and for Four Different Periods and Planted in the Field for Performance Studie s. ...... 25 V. Conclusion 33 VI . Acknowledgements. 34 VII. References Cited 35 Digitized by the Internet Archive in 2016 https://archive.org/details/somefactorsaffecOOdung SOME FACTORS APR EC TING WATER ABSORPTION AND GERMINATION OP SEED CORN. I. Introduction Agricultural Experiment Stations and teachers of Agriculture throughout the corn belt are quite unan- imous in their advice to the farmer concerning the se- lection and care of seed corn. The man on the farm alter is urged to harvest seed corn while it is in the dent stage, before the first killing frost, and to store it under conditions that insure rapid curing. During the curing process the temperature must be controlled so that it will not fall to or below the freezing point; and provision must be made for proper ventilating facil- ities that will allow a rapid and effective circulation of air. After the moisture in the corn has been reduced to 12 or 14 per cent, the manner of storage is immater- ial so long as the ears are protected from direct expo- sure to the weather. Just how long it will take for corn to reach a moisture content of 12 to 14 per cent is difficult for the farmer to determine. To be sure of complete curing he has been usually leaving his corn in the curing house unduly long and thus reducing the moisture content below 12 or 14 per cent. This contin- ued curing no doubt, injures the grain as seed corn. One of the topics for the present investigation is to find the effect that time of harvesting and thorough- of drying ness/ has on the grain used for seed. It lias been long understood that the physiolog- ical activity in seeds is controlled to a great degree by the moisture in them. The quantity of water present in the seed during the dormant or storage period that will give the best growth and yield in the field has never been definitely worked out. The federal system of grading c or n ; promulgated in July 1916. has placed the most desirable moisture content of corn for safe keeping in storage at 14 per cent or below. The grading of corn involves a determination of test weight per bushel, per cent water contained in the sample, damaged corn which includes moldy kernels, heat damaged grains, etc. and foreign material and cracked corn. Water in corn is the most detrimental factor to its safe preservation in storage. It lowers the specific gravity of the corn and tends to contribute to the con- ditions that develop mustiness and heat damage. The only factor into which water does not enter in grade determination is foreign material and cracked corn. On the other hand, the absorption of water is the initial process in germination and growth. This report pre- sents what was learned in the laboratory concerning the rapidity of water imbibition and speed of germin- ation when corn of various initial moisture contents “ . ' was used. -3- Many farmers have observed that some types and varieties of corn sprout sooner in the field than others. This problem includes a study of two different types of corn and corn of the same variety but having different chemical composite on. It has been reported that the practice of soaking corn in water previous to planting is advantageous, espec- ially if the planting is done late. Some trials were made to get some information on this question. II. Literature Kiesselbach and Ratcliff* report that from the standpoint of autumn freezes corn containing from 15 to 20 per cent of moisture is safe; and corn with 10 to 14 per cent of moisture will stand the most severe winter temperatures without injury to its germinative power. The fatal minimum moisture content of protoplasm is fixed by p Ewart at two or three per cent. Water absorption by seeds is the first step in their germination. Atkins in his imbibition studies working with beans and peas noted that the rate at which distilled water is taken up is no greater than that at which salt solutions are absorbed. Seeds placed in nor- mal sulphuric acid, decinormal iodine, decinormal sodium chloride produced no concentration of these solutions. This was taken to prove that there is no semipermeable membrane in bean seed until germination begins when the - 4 - cell protoplasm acts as such, and that there is no differ- ence in absorption between living and dead seeds until after germination when the protoplasmic membrane is formed. Brown and Worley 4 worked with barley grains and made water absorption studies at three different temperatures. They concluded that the velocity with which the water is absorbed by the seed is almost exactly an exponential function of the temperature. This is explained by presum- ing that cold water contains a relatively high proportion of "hydrone" (0 H2J2 whi 0 * 1 upon being warmed breaks down into the simpler molecules. It would appear that only these simpler molecules are directly assimilated by the seeds or transmitted by the differential septum. Shull 5 states that it is his conviction after a number of years of experience with absorption phenomena, that absorption is a complex process dependent on a number of factors, some of which may be external, but many of which are in- ternal. His work with Xanthium seeds and split peas in- dicates that absorption is both chemical and a physical process that is not entirely dependent upon temperature. Soaking seeds previous to planting often hastens germination. Increased crop yields have been reported as the result of swelling seeds in water . 6 Recently Braun 8 has shown that the presoak method of seed treatment is an effective means of preventing seed injury due to chemical disinfectants and that this also increases germicidal ef- ficiency. \ . -5- The soaking of seed prior to planting never has had a wide practical application. However, when more is learned concerning the relation of temperature during early growth and later development, it may be profitable to swell seeds at the temperature found most desirable for 9 maximum production. Walster's work with Oderbrucher bar- ley grown in sand cultures maintained at 15 degrees and EO degrees centigrade is suggestive in this connection. The plants growing at the lower temperature were much more % upright in growth habit, produced a greater proportion of culm to leaf, a greater proportion of skeleton material in the leaf and a greater degree of lignification of con- nective tissues in both leaf and culm. III. Materials and Methods The corn used was largely of the He id's Yellow Dent variety having medium rough indentation. It conformed very closely to the type that was considered as standard by the Illinois Corn Growers Association prior to the adop- tion of the Utility Score Card in January, 1921. Part of this corn came from Professor J. G. Hosier's farm, south of Urbana^ana part of it was produced on the Agronomy South Harm of the Agricultural Experiment Station. Part of the corn was harvested at three different stages of its development; viz., milk stage, dent stage, and mature stage. Corn was considered to be in the milk stage when the content of the kernels had changed from its earlier watery form to a milky liquid having the con- •• ' , . * - 6 - sistency of cream. This point ih the development of the grain of corn was practically the same as that desired by users of roasting ears or cut corn for the table. In the dent stage development had progressed until the internal composition of the kernel had the consistency of dough and the crown of the grain had a small dimple dent. The husks were brown and dry, and the stalks were still green. Fanners are commonly advised to harvest their seed corn when it is in this period of its development. The mature samples were harvested at the time the corn was dry enough to begin cribbing. The kernels were completely dented and dry, and the ears contained approximately 20 per cent of water. The ears were taken to the greenhouse and allowed to dry at room temperature. During the winter after all the corn had reached an approximately uniform moisture content, imbibition and germination studies were made at a number of constant temperatures. For the investigation on the influence of quanti- ty of initial moisture on the speed of water absorption and vigor of germination, corn was taken directly from a crib. Ears were chosen on the basis of moisture content as determined by handling and visual appearance, and grouped into classes. Each class was shelled separately and thor- oughly mixed forming a composite sample. A moisture de- termination was then made by the Brown -Puvel Moisture Tester Apparatus. It was planned to obtain composite sam- ples of corn representing all grades from 1 to Sample in- clusive. The Federal Grades in respect to moisture are - 1 . ■ • . -7- as follows: Grade designation Maximum moisture content Grade 1 14 $ Grade 2 15.5 Grade 3 17.5 Grade 4 19.5 Grade 5 21.5 Grade 6 23 Grade Sample More than 23$ Each grade of corn was then poured into a separate mason jar and carefully sealed to prevent further desiccation. Imbibition studies were made as soon as practicable to avoid any deterioration of the corn in the sealed jars. However, some of the grades containing large quantities of water fermented and rapidly molded. Because of this rapid deterioration in storage it was deemed advisable to collect the samples of high moisture content as they were used. Pour ears each of Illinois High Protein, Illinois Low Protein, Illinois High Oil and Illinois Low Oil were obtained from the one year old seed stock of the Plant Breeding Division. Each ear of the high and low protein corn had been analyzed chemically and the data giving the amount of protein wets furnished. !The oil percentage was also known for every ear of the high and low oil types. The corn from these ears was studied both from the stand- point of rate of imbibition and rapidity and vigor of ger- . ;■ . - 8 - raination. The seed that was used in the investigation of the effect of presoaking on the growth and yield of corn, was obtained from James R. Holbert, Bloomington, Illinois. It consisted of diseased and disease-free corn of Reid's Yel- low Dent and Bunk's Ninety Day varieties. Its diseased condition and freedom from disease had been determined by Mr. Holbert in germination tests on his neutral base or saw dust lime germinator. % In the imbibition studies a definite number of grains (either 25 or 50) were counted out and carefully weighed to within one centigram. The weighed corn was then poured into jelly glass jars. Two samples were prepared for each of six temperature chambers. These chambers were main- tained at constant temperature - not varying as much as one- half a degree centigrade day or night. The temperatures used were 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, and 30 degrees centigrade. When the com was placed into the temperature chambers it was covered with distilled water which had the same temperature as the cham- bers. At the end of the test the water was drained off and the corn dumped onto a dry absorbent towel. A corner of the towel was folded over the corn and rubbed hurriedly for a few seconds. The corn was then turned onto a second dry towel which was also folded over the kernels and rubbed until all superficial moisture on the grains was removed. The weight of the kernels was then obtained. Most of the imbibition determinations covered a twenty-four hour period, . . -9- but there was one series which was dried and weighed hourly for twenty-four hours. In order to make the soaking periods the same for all samples, new samples for the next day's work were put into the chamber as the ones to be dried and weighed were taken out. Water absorption calculations were made with the weight of water-free corn as the basis. Ger- mination studies were made on plaster of Paris blocks. Slabs of plaster of Paris two inches thick and eight inches square were laid in galvanized iron pans. Water was poured over these until it came within approximately one-eighth inch of the top of the blocks. Grains of corn were then laid germs up on the plaster of Paris slabs. The cover was placed over the pan which was set into the temperature chamber. By this method when the lid was removed from the pan, every step in the germination process was easily vis- ible. IY. Results. Influence of Stage of Harvesting Corn on Its Water Absorption and Germination The corn that was harvested at different stages in its development had approximately reached the same mois- ture content when the imbibition studies were made. The milk stage corn had 9.5$ of water. The dent stage corn contained 10.7$ and the completely mature grains 10.3$. The average weight of the kernels showed very striking differences. The early picked corn weighed approximately one half as much as the mature corn. Of 300 kernels of corn the aver- age weight per grain harvested in the milk, dent, and ma- , . . - , - . . ' Percentage water after 24 hour-5 soaking - 10 - ture stages was .163, ,268, and .320 grams, respectively. The amount of water absorbed in a twenty-four hour period by each lot of corn appears below based on the weight of water-free corn: Table I. Water imbibed by corn harvested at 3 different stages of maturity during a period of 24 hours soaking in water maintained at 6 different con- stant temperatures. Temperature Water imbibed by corn harvested in Milk stage 'Well dented stage Mature stage 5 degrees C 74.130 64.055 46.275 10 degrees C 85.160 68.710 53.970 15 degrees C 89.905 70.025 57.975 20 degrees C 90.075 71.780 59.255 25 degrees C 94.385 72.900 60.930 30 degrees C 91.465 72.565 61.070 Average 87.520 70.006 56. 589 It is evident that early harvesting of corn influ- ences the rate of water intake. Seemingly the maximum capacity for water is higher in immaturely picked corn than in that gathered later. This is probably due to the great- er quantity of sugars in the earlier harvested grain. The "milk” and "dent" corn absorbed slightly less water at 30 degrees dentfgrade than at 25 degrees centigrade whereas the mature corn increased its water content at 30 degrees centigrade. The increase in water absorption for each 5 degree rise in temperature is much more clearly shown in - 11 - graph I than in the table. Duplicate germination tests of 50 grains each were made of each sample of corn on plaster of Paris blocks at 1& , 20, 25 and 30 degrees centigrade. Observations were made daily, and records of the progress of seedling development taken. The grains that had sent out a radicle only, were counted separately from those that had produced both a radicle and plumule. Table II summarizes the information collected in these tests. The columns headed "r" give the radicles only , while ! r p' includes both the radicles and plumules. Table II. The Germination of corn harvested at three dif- ferent dates and germinated at four different con- stant temperatures. Tem- pera- ture Corn used Av arage percents tge germination in 2 days 3 days 4 days 5 days 6 days 18 days Per cent vitality . r r £ r rp r rp r r F r rp r rp 15° Milk 0 0 0 0 0 0 0 0 0 0 0 0 0 Dent 0 0 3 0 7 0 7 Mature 0 0 0 0 0 0 0 0 0 0 0 0 0 20° Milk 9 0 23 1 69 11 43 37 29 63 — - 92 Dent 10 1 17 3 34 34 30 49 17 75 - - 92 Mature 1 1 10 12 36 26 22 46 11 83 - - 94 25° Milk 17 0 35 4 48 32 24 62 22 66 * 88 Dent 23 1 33 7 28 62 IS 78 9 88 - - 97 Mature 3 — 1 27 3 35 58 4 91 4 93 - - 97 30° Milk 36 7 39 25 24 66 - - - - - - 90 Dent 29 9 30 32 20 73 93 Mature 27 0 36 20 15 81 — - - - - 96 - 12 - The figures presented suggest that even though ex- tremely early harvested corn absorbs water quickly and in large quantities the speed of germination during the first three days is only slightly greater than in "dent” corn. Later the "milk" corn is overtaken by the more mature ker- nels which at the end of the test surpass it in vitality. This lower vitality expressed in germinati onal vigor may be explained on the basis that the immature corn had not received sufficient or properly balanced translocated material from the parent plant before it was harvested. The dent corn is more rapid in germination than the mature corn, but it is surpassed in viability by the latter. It may be noted that at 30 degrees C. the immature corn had produced 36 "r's" and 7 "r p's" in two days during which time the "dent" corn had sent out 29 "r's" and 9 "r p's" and the mature corn 27 "r's” and no "r p's". At the end of the third day the "dent" corn had developed 32 plumules as compared to 25 and 20 for the "milk" and "mature" corn, respectively. The close of the fourth day shows the"mature" corn to be much superior to either of the others and the "dent" corn much better than the "milk" sample. The same striking differences appear at the end of 6 days at temper- atures of 20 and 25 degrees C, except that at 20 degrees the plumule production of the milk corn does not at any time equal that of that harvested later. This leads to the con- clusion that low temperature favors root development and retards the growth of the shoot. -13- Affect of Initial Moisture in Corn on Its Water Absorption and Germination. Five of the seven grades of corn were used in the studies of imbibition. The original moisture content of the samples and the quantity of water taken up during twen- ty-four hours at the six temperatures appears in Table III. The lower half of the table shows the amount of water that was absorbed over and above the moisture already present in the seed. Table III. Imbibitional study of corn containing different amounts of initial moisture. Percent Percentage the basis of period of soa moisture in corn calculated on water-free corn after a 24 hour king in distilled water at - Grade moisture content 5 10 15 20 25 30° C One 13.9 34.30 45.69 46.49 49.51 52.34 55.03 Two 14.2 43.42 49.11 49.41 53.59 53.76 58.89 Four 18.3 42.96 48.28 50.12 54.30 55.87 60.38 Five 20.2 41.72 46.54 50.15 53.88 56.58 59.93 Sample 23.5 50.02 54.40 57.00 60.55 61.28 67.71 Moisture content Perc< during antage moisture taken up by the corn a 24 hour period at - Grade 5 10 15 20 25 30° C One 13.9 21.40 31.79 32.59 35.61 38.44 41.13 Two 14.2 29.22 34.91 35.21 39.39 41.56 44.69 Four 18.3 24.66 29.98 31.82 36.00 37.57 42.08 Five 20.2 21.52 26.34 29.95 33.68 36.38 39.73 Sample 23.5 26.52 30.90 33.50 37.05 37.78 44.21 -14- It is evident from a study of the above data that the natural moisture in corn is not the only factor or at least not the direct factor that influences the quantity of water absorbed. The elements that enter into the imbibi- tional process and bring about wide differences in amount of water taken up at 5 degrees are less potently operative at 30 degrees. The corn containing 14.2# initial moisture leads all of the samples in amount of water absorbed. This is followed by Sample grade, with grades one and four run- ning close together. Grade five has taken on the smallest quantity of additional water of any one of the series. For the germination phase of the problem on the influence of initial moisture on rapidity of seedling devel- opment, three samples of corn having a moisture content of 6.1, 12.6 and 19.2 per cent, respectively, were obtained. These were germinated at 10, 20, 25, and 30 degrees C. « . . -15- Table IV. Germination testa of corn oontaining different amounts of moisture. Case Moi3tur Content of corn used <} Average percentage germination at end of Total % Vital- ity 2 days 3 days 4 days 5 days 6 days 7 days 8 days 18 days r rp r rp r rp r rp r rp r rp r rp r rp 10° 6.1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12.6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 19.2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 7 3 10 o o * — 87 12.6 44 0 73 12 20 80 100 19.2 55 0 61 19 14 72 86 03 o O 6.1 91 0 29 63 92 12.6 97 0 9 88 • 97 19.2 B5 0 12 73 85 At 20° after 5 days the ”19.2 per cent” c produced 12 ”r's" and 1 ”r p” t the ”12.6 per cenl ”r's” and 1 ”r p”, and the ”6.1 per cent” corn h£ gun to germinate. This behavior would suggest ti initial moisture in corn will give rise to rapid tion. The advantage the more moist sample had is however, at the close of the sixth day. The resu tained after days at 25 degrees are in accord cited above at 20 degrees. The third day at 25 c sorn ;” c( id nc lat 1 gern lOE tits wi t? egre ha )rn )t lig iin it, ob i t es d 8 be- ll a- hos 56 -16- shows 19, 12, and no "r p's” for the "19.2%" and "6.1%" corn, respectively. The order changes in favor of the "12.6%" corn on the fourth day. The readings have not been con- tinued long enough to indicate whether the "r p" produc- tion would finally swing to the drier corn, but the data taken the eighteen day at 20 degrees suggest such a pos- sibility. There is also some very good evidence brought out in this table to lead to the conclusion that corn con- taining a3 little as 6.1% qioisture is too dry for strong 100 percent vitality, and that corn having as much moisture as 19.1 per cent is too moist for best germination, al- though the development of the embryos that are viable, is rapid. Moisture in seeds is commonly considered the most influential factor in determining the life processes going on within them. It would seem that with "6.1%" corn desic- cation had progressed so far that life activity was mater- ially reduced making renewal of these functions tardy and in some of the seeds difficult or impossible. The "19.2%" corn has been carrying on rapid respiration for so long that it is weakened and many of the germs are dead. The initial germinative processes are rapid, but the value of this corn for seed purposes is not nearly as great as that of the ”12.6%" corn. Composition of the Corn Kernel and Its Water Absorption Pour ears of the Illinois High Oil, Illinois Low vil, Illinois High Protein and the Illinois Low Protein ' . f . « r , • * . • * r -17- were obtained of Mr. Louis Hunter of the Plant Breeding Livi-’ sion. Prom the high and low oil ears three rows of kernels from each ear had been taken for an analytical determination of the percentage of oil. The high and low protein corn had been sampled similarly for protein determination. The results of these analyses show wide extremes in kernel com- position. Table V. Percentage of Protein and Oil in Lars of Extreme Types with respect to these Constituents. Ear No. Type Moisture Content Percentage Protein Percentag Oil e Averag 15 High Oil 8.14 - 9.51 36 u ii 6.84 - 9.11 (Oil) 41 ii ii 7.09 - 9.61 91 ft ii 7.26 - 9.38 9.40 26 Low Oil 8.49 - 1.83 33 TT ii 8.81 - 1.90 (Oil) 73 ii ?? 8.19 - 1.62 102 ii ft 10.04 - 1.73 1.82 19 High Protein 6.85 5.15 - 26 Tt ii 7.02 14.26 - (Pro- t ain) 47 ii !? 5.87 15.90 - 69 ii it 7.26 15.56 L5.29 3 Low Protein 7.00 6.50 22 ii T? 7.35 5.90 (Pro- t ain) 25 ii ii 8.30 6.00 - 96 tr ft 7.85 5.98 _ _ J j >,095 -18- The high oil corn contained 5.16 times as much oil as the low oil strain, while the protein content of the high type was £.18 times that of the low. Twenty-five kernels in duplicate from each ear were soaked in water for £4 hours. The results obtained appear below. Table VI. Imbibition in Corn from Individual .Ears of Special High and low Oil, and High and Low Protein Corn. Type Ear Ho. Percentage water in the in water at corn after soaking 5 10 15 20 25 30° C High Oil 15 38.52 40.02 45.45 49.10 50.76 50.57 IT it 36 32.76 38.00 44.65 46.53 4 7.90 50.63 II »? 41 38.36 41.21 45.50 49.66 52.41 56.00 tt it 91 34.17 37.85 45.14 48.91 50.33 53.47 low Oil 26 40.66 42.08 45.54 50.67 52.69 54.19 If ii 33 33.15 37.71 43.24 46.72 48.93 50.51 It T! 73 30.65 33. 64 41.08 43.68 45.06 47.59 it • It 102 33.85 39.28 45.25 50.28 50.59 52.83 High Prote in 19 28.82 31.33 35.84 41.58 43.47 45.47 it ft 26 30.96 30.71 39.29 43.12 46.80 48.29 >1 ff 47 26.82 30.01 35.01 41.47 44.20 46.05 i» It 69 30.09 34.55 39.74 44.93 45.55 47.21 low Protein 3 34.91 40.14 43.91 47.82 49.75 51.38 n II 22 36.02 39.21 46.07 50.48 55. 79 58.64 it 11 25 35.82 39.09 44.59 48.25 49.45 57.80 i? II 96 37.39 39.59 44.98 48.68 52.78 53.82 . I r» 19- iJars number 15 and 41 of the high oil series are consistently higher in water content, than the others, with the single exception of ear number 91 at 30°C. har ”36” is rather uniformly lower in water intake than the other three in this group. It is also slightly lower in oil content, and somewhat lower in original moisture. While the results are not conclusive, they are suggestive that slight increased quantities of oil in corn is associated with greater water absorption. Practically all the oil in corn is located in the germ region. High oil corn pos- sesses a very large germ in proportion to endosperm. It is presumably the rapid intake of water by the large germs that gives the higher imbibi ti onal curve for the high oil corn. With the low oil corn, the correlation between orig- inal moisture content or slight variations in oil percentage, and quantity of water absorbed does not seem to be signi- ficant. The differences that appear at five degrees carry through uniformly with but few exceptions. The fluctuations between corn of so nearly the same composition in respect to oil must be due to unknown individual ear variations. It will be noted that our ear number 26 which is more than one per cent lower in protein than its three compan- ions, has absorbed slightly more water than the others, har number 47 which is highest in protein has imbibed the least amount of water at four of the six temperatures. High pro- tein even when differences are very slight, appears to hinder water absorption. Since ear number 47 is the lowest - - 20 - in origi na i moisture content and the highest in protein composition it would seem that the presence of protein favors dee legation. Low protein ear number 22 is the lowest in protein content and the highest in water content at four of the six temperatures. kar number 3 is the highest in protein of any of the ears of the low protein group, and is the lowest in absorption in two-thirds of the trials. In order to present more clearly the performances of each of the four groups of corn the data from the indi- vidual ears have been averaged and are shown in Table VII and Graph II. Table VII. Average of Imbibitional Lata from High and Low Oil and High and Low Protein Corn. Type Percentage wa ter in the corn after soaking in water at Aver- age 5 10 15 20 25 30°C High Oil 35.95 39.27 45.19 44.55 50.35 52.92 45.37 Low Oil 34.58 38.18 43.78 47.84 49.29 50.03 43. 95 High Protein 29.17 31.90 37.47 42.78 45.01 46.76 38.85 Low Protein 36.04 39.51 44.89 48.80 51.94 55.41 49.10 The low oil corn possesses a much larger proportion of endosperm than does the high oil strain. The starches and sugars of this part of the kernel take up water almost as rapidly as the unusually large germs of the high oil corn. In the high protein com, the protein is carried largely in the aleurone layer and in the horny starch ' - 21 - around the outer walls of the endosperm. This serves as a semi-impervious layer around the soft starchy portion within, and protects the germ from contact with water except from one side. The low protein corn contains a much larger tis.sue proportion of soft starch^with very little and often none of the horny tissue surrounding it. This permits ready intake of water. The germination of this corn on plaster of Paris blocks at 20, 25, and 30° temperatures shows results some- what different from those obtained in water absroption studies. The detailed notes concerning the germination appear below in Table VIII. The type of corn is indicated by the initial of the strain name as "L.O." for Low Oil, H.r ." for High Protein, etc. The percentage number of kernels that had produced radicles is indicated by "r"; both radicles and plumules by "r p”; seminal roots by M s r"; leaf emergence through the coleoptile by "le" ; plumules that were produced without radicles by w p” ; and the average length of the plumule in inches by "p 1”. - 22 - Table VIII. Germination of High and Low Oil and High and Low Protein Corn at 20, 25 and 30° C. ' I)e-~ ' 20° Is 5 ’ ■ — 30° Time vel- ?|Tne ( Days ) op- LO pn J 1 1 1 ( J H o i : m ? L *( 3 H( HP H~P .Kent, . . __ m ^ t , _ u _ 2 r 0 0 0 0 0 0 3 0 0 6 0 0 r 0 0 0 0 0 24 70 75 37 31 58 _ 68 3 rp 0 0 0 0 0 12 3 3 3 46 20 18 sr 0 0 0 0 0 6 3 0 0 30 3 3 r 0 0 0 0 49 *27" 40 18 45 0 '48 18 4 rp 0 0 0 0 0 73 58 82 37 94 45 83 rs 0 0 0 0 0 45 26 50 25 86 25 73 r 0 u '