Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. May 21, 1923 _ INFLUENCE OF SPACING ON PRODUCTIVITY IN SINGLE-EAR AND PROLIFIC TYPES OF CORN. By E. B. Brown, Agronomist, and H. 8. Garrison, Assistant Agronomist, Office of Cereal Investigations, Bureau of Plant Industry. CONTENTS. Page. | Page. Single-ear and prolific types of corn.......-... 1 | Results of the experiments.................- 5 Location and plan of the experiments........ #.\ Analysis of the yields... - ¢ 22-4... -3-s-2-<60 8 Description of the varieties............-...-. Deja ONCIUSIONS Shean seese ae oe oe = Sane se as 10 SINGLE-EAR AND PROLIFIC TYPES OF CORN. Throughout the southern portion of the United States both the _single-ear and prolific types of corn are more or less commonly grown. The distinguishing characters of the single-ear type are the usual pro- duction of but one well-developed ear per stalk (Figs. 1 and 2), large ears with numerous rows of kernels, and large cobs (Fig. 3). Under very favorable conditions two well-developed ears may be produced, _ but ordinarily secondary ears are stubby in appearance and classed - asnubbins. In no variety, so far as known, is there a complete inhi- bition of secondary ears. As contrasted with the single-ear type, the prolific is distinguished by the normal production of more than one ear per stalk (Figs. 4 and 5). The ears usually are smaller and more slender, with fewer rows of kernels and smaller cobs (Fig. 6). The demarcation between the two types is not absolute. Between the two extremes varieties occur that are more or less intermediate and that can not be placed accurately in either class. In each type there are occasional plants that vary toward the opposite type. By the selection of seed from such individuals it would be possible to segregate a prolific strain from the single-ear type or a single-ear strain from the prolific. It is reasonable to assume that the development of the single-ear type has resulted from a more or less continuous selection toward a large ear. With this there has gerp oped a tendency toward a high number of rows of kernels, large cobs, the suppression of extra shoots, and the development of but one ear per stalk. In the development of the prolific type the characters that have been perpetuated and intensified are the production of more than one ear per stalk and of small slender ears with usually a low number of rows of kernels and small cobs. It seems probable that in the single-ear type the char- 35697—23—Bull. 1157 2 BULLETIN 115i, U. S. DEPARTMENT OF AGRICULTURE. actergof one ear per stalk has become more or less stabilized, whereas the character of weight of ear has remained in a more variable condi- tion. In the prolific type the number of ears per plant doubtless would be a more variable character than weight of ear. _ Although both the size of ear and the number of ears per stalk are limitedjby heredity, their expression will be determined largely by \ . ) SO Yo ay i 4 t Fig. 1.—Typical single-ear plant of corn. Fic. 2.—Typical single-ear plant of corn. Height, 6 feet 3 Height, 11 feet. inches. Although not so tall, this plant was later in maturing and produced a larger ear and apparently as much foliage as the plant shown in Figure 1. their environment. Other things being equal, the productiveness of the plants will be determined by their spacing. On land of uniform ality the productiveness of the plant will tend to be in direct pro- portion to the area of land it occupies. In these experiments the spacings have provided a range of approximately 3 to 30 square feet per plant. The reaction of the varieties, as revealed in total yields, NS INFLUENCE OF SPACING ON PRODUCTIVITY OF CORN. 3 roduction per plant, average weight of ear, and number of ears per lant, has been determined and the results tabulated. As the area per plant is increased it is obvious that an increase in production per plant will be either through an increase in the weight of the ear or an increase in the number of ears, or both. Fic. 3.—Large single-ear type of ear of Fig. 4.—A prolific plant of corn having corn, 12 inches long with 20 rows of numerous ears but no suckers. Height, kernels; weight (air-dried), 22 ouinces. 8 feet 10 inches. If the development of the single-ear type has been along the lines suggested, the greatest response to better environment would be an increase in the weight of the ear, with the production of more ears per plant as a secondary response. In the prolific type the greatest response to better environment would be an increase in the number of ears per plant, with increased size of ear as a secondary response. As both types are grown extensively, it is of agronomic interest to know which yields more efficiently under ordinary field conditions 4 BULLETIN 1157, U. S. DEPARTMENT OF AGRICULTURE. where the production of the plants is likely to be influenced by irregularity of stand and by inequalities in germination, soil, and growing conditions. The purpose of the present investigation was to study the reaction of these types under conditions that provided a wide range in the environment, obtained in this case by altering the spacing of the plants. The results should indicate their comparative values. LP eh oe ae - Lom 4 e; ie EP ‘ = ©. r ae 1G0G, 00000 eng LON 0g Uy, hhhap a A AAA Fics pe Gaevegcecararn, Co0Cecge nevontee acc a % a ee, oe , feel Pe oS oS a ae J = = oe Scot » Som SS 7 ‘F< dceane 1Gdaneica a SS FEE % KCANCOE dal ita tae ete trea 'oTCcGodecggecgogaag favaq 49' ate #ar . il Fig 5.—A typical prolific plant of corn that has produced Fic. 6.—Prolific type of ear of corn, 9 both ears and suckers. Height, 10 feet 6 inches. inches long with 12 rows of kernels; weight (air-dried), 12 ounces. LOCATION AND PLAN OF THE EXPERIMENTS. The experiments were located at Clarksdale, Miss., at Waco and San Antonio, Tex., and at the Arlington Experiment Farm, Rosslyn, Va. The plan of the experiments was’to grow both types of corn at different spacings to determine which would show the greater adapta- bility, judged by its yield. In the experiments conducted in Missis- INFLUENCE OF SPACING ON PRODUCTIVITY OF CORN. D sippi_and Texas the varieties were planted in drills; in those at the _ Arlmgton Experiment Farm the plantings were in hills. The corn was planted more thickly than required, and when the plants were 6 to 8 inches tall they were thinned to the spacing desired. The spacings were controlled in the drill plantings by varying the _ distance between individual plants in the row, whereas in the hill ta eoume the hills were uniformly spaced and the stand was controlled _ by thinning to the desired number of plants per hill. The experimental! plats at Clarksdale were on fertile “‘delta”’ land of uniform appearance that had been cropped to cotton in the preceding years. The rows were 3.89 feet apart and 211 feet long in 1917, and 3.49 feet apart and 104 feet long in 1918. At Waco the plat was on uniform sandy soil, characteristic of the Brazos River valley, cropped the previous year to cotton. The plants were grown in rows 3.15 feet apart and 100 feet long. At San Antonio the plats _ were on black upland of uniform appearance during the entire three _ years of the experiment. The corn occupied land on which cotton had been grown the preceding year. The plants were grown in rows _ 4.1 feet apart and 132 feet long in each of the three experiments. _ At the Arlington Experiment Farm in 1917 and 1918 the plats were on upland of uniform appearance. The plat used in 1917 had been in sod the previous year, and the plat used in 1918 had been cropped to soy beans the preceding year. The plats used in 1919 and 1920 were on uniform reclaimed river land on which corn had been grown in the preceding years. The plants were grown in hills 3.3 feet apart in each direction. DESCRIPTION OF THE VARIETIES. The single-ear type was represented by four varieties and the prolific type by three varieties. These varieties are listed and described as follows: saps te < eS | + eat ted ne iia ay pS Tm (area SINGLE-EAR VARIETIES. U. S. Selection 120, white dent, ears 74 to 94 inches long, kernels broad, indentation smooth to slightly rough, 12 to 14 rows, 60 to 65 days from germination to flowering. Singleton, strawberry dent, ears 8 to 10 inches long, kernels longer than broad, indentation slightly rough, 16 to 20 rows, 65 to 70 days from germination to flowering. Wilson, yellow dent, ears 83 to 11 inches long, kernels longer than broad, indentation smooth to rough, 18 to 22 rows, 55 to 65 days from germination to flowering. Delaware White-Cap, white-capped yellow dent, ears 8 to 10 inches long, kernels longer than broad, indentation slightly rough, 18 to 24 rows, 60 to 70 days from ger- mination to flowering. PROLIFIC VARIETIES, Cocke Prolific, white dent, ears slender, 7 to 84 inches long, indentation smooth, 10 to 14 rows, 65 to 75 days from germination to flowering. Arlington Prolific, white dent, ears slender, 74 to 8 inches long, indentation smooth, 12 to 16 rows, 65 to 70 days from germination to flowering. Biggs Seven-Ear, white dent, ears slender, 7 to 84 inches long, indentation smooth, 10 to 14 rows, 60 to 70 days from germination to flowering. RESULTS OF THE EXPERIMENTS. Data from the experiments conducted at Clarksdale, Miss., in 1917 and 1918 are shown in Table 1. The prolific outyielded the single-ear type at every spacing. Using the results obtained at the closest spacing in each experiment as bases for calculating the rela- tive gains made as the spacing increased, there is a total of seven comparisons between the two varieties. In these, the single-ear type 35697—23——2 6 BULLETIN 1157, U. S. DEPARTMENT OF AGRICULTURE. made a greater relative gain in yield per plant four times, in th weight of ear seven times, and in the number of ears per plant once. TaBLE 1.—Influence of spacing on yield, weight of ear, and number of ears per plant in single-ear and prolific types of corn: grown at Clarksdale, Miss., um 1917 and 1918. Weight of dry ear corn (pounds). Area occupied Number of z x | | Number of | Number of — per plant plants per Yield. | | ears per suckers per (square feet). | row, | Average per plant. plant. ear. Year. | Per row. | Per plant. Single| Pro- Single Pro- |Single, Pro- Single} Pro- Single} Pro- Single| Pro- |Single| Pro- ear. | lific. | ear. | lific. | ear. | lific. | ear. | lific. | ear. | lifie. | ear. | lific. | ear. | lific. 88.2 0.351 0.426 0.419 | 0.434 0.84 | 0.98 | 0.03 0.11 4.04] 3.97| 203| 207 | 71.2 6.06 | 6.36| 135| 129 | 74.8| 84.8) .554| .657|..562| .511| .99 | 1.29 | .06| 22 1917... 8.30| 7.96| 99] 103 | 73.6| 88.0] .743| .954| .657| .515| 1.13 | L66 | .37| 36m 11,73 | 12.06 | 70| 68| 58.2| 76.4| .831| 1.124! .693| .616) 1.20 | 1.82 | 114] .25 13.45 | 13.69, 61| 60 | 44.2|60.6| .725| 1.010, .691| .594| 1.05 |1.7c | .06| .18 6.05 | 6.15 60 59 | 16. 1918 eda do bl 47 47 | 16. -"1)11.00 | 10.37 33 35 | 14. 17. 28 | 17.28 21 2 Le: | | | 0.6 3.2 | .267| .393 | .348| .318| .767| 1.236)/0 | .08 0.6 | .340/ 438; .400| .312) .851/ 1.404| .c4) . 6.4) .424| .754) .438) .383| .970/ 1.971) .15| .57 7.6) .715) .838 .469 | .400 | 1.524 | 2.095 . 86 | 2 2 2 1 ocoonoe 1 The varieties used in 1917 were, U. S. Selection 120 (single ear) and Cocke (prolific); in 1918, Singleton (single ear) and Arlington (prolific). The data obtained from the experiment conducted at Waco, Tex., are shown in Table 2. Owing to a severe drought, the yields in this plat were negligible. The tabulated results are of interest chiefly because they show that under these adverse conditions the small- eared prolific type produced more efficiently and actually made heavier ears than the single-ear type. TABLE 2.—Influence of spacing on yield, weight of ear, and number of ears per plant in single-ear (Singleton) and prolific (Arlington) types of corn grown at Waco,~Tex., in TDISs | | | Weight of dry ear corn (pounds). Area occupied) Number of | , : Number of | Number of | perplant | plants per | Yield. | ears per suckers (square feet). | row. | Average plant. per plant. Year. | per ear. | Perrow. | Per plant. Le oe | Pe baal Single} Pro- Single} Pro- Single Pro- | Single} Pro- |Single| Pro- Single | Pro- |Single|} Pro- ear. | lific. | ear. | lific. | ear. | lific. | ear lific. | ear. | ific. | ear. | lific. | ear. | lific. : | | saeicl Pe. | am sisy| 3 | | | | | | | 3.45 | 3.28 Of *). = 296") ONG 1.2 | 0.007 | 0.012 | 0.067 | 0.085 | 0.099 | 0.146 |.....- 0 1918 6. 43 T000K Ah 45 40).| 840°)" 3082). 2086-) -. 148° (143) 572 622902027 aso 2-110; 50 1°10..85 |; 300° 29 1 4.6 187 20]! 2158 i 2ase| 184°) 6 218 1 Sa ess ae ee 15.75 | 15.00 | 20 Z| 2265|7 91.2 | 180 | .343 | 144 | .257 |} .9004 1.334] .05) 0 In Table 3 are recorded the data from the experiments conducted at San Antonio, Tex., in 1918, 1919, and 1920. The prolific out- vielded the single-ear variety in 14 out of 16 comparisons. A com- parison of the two varieties as to relative gains as the spacing increased, based on the results obtained at the closest spacing in each experiment, show that:in 13 comparisons the single-ear type made greater gains once in yield per plant, seven times in the weight of ear, and four times in the number of ears per plant. INFLUENCE OF SPACING ON PRODUCTIVITY OF CORN. TABLE 3.—Influence of spacing on yield, weight of ear, and number of ears per plant in __single-ear (Singleton) and prolific (Arlington) types of corn grown at San Antonio, me Jex:, in 1918, 1919, and 1920. : | Weight of dry ear corn (pounds). r: Area occupied Number of | F- per plant —_— plants per Yield. ee (square feet). row. Average » Year. | ‘per ear. - Per row. | Per plant. | = - = ; Single} Pro- Single Pro- |Single| Pro- |Single| Pro- |Single| Pro- : | ear. lific. | ear. | lific. | ear. | lific.| ear. | lific. | ear. | lific. | = | | Cia oe > 4.10} 4.67 132) 116 | 59.3 | 54.0 | 0.449 | 0.465 | 0.468 | 0.377 = 6.20 | 5.87 S5 | 925 45.7). 46:7.) 5388 | .508 |. 50841 .459 4918 8.00; 8.00 68 68 | 41.2 | 56.2} .606 | .826 | .570 | .434 ~-7|)14.70 | 14.00 37 | 39 | 32.8 | 45.0] .886 | 1.155 | .548 | .489 15. 86 | 16.58 34) 33 | 27.2 | 34.8 | .8007) 1.055 | .542] .407 ; | 20.50 | 19.50 | 26 2B IS. TS2,.00\- 7205) We142a- 2514: 353 : { 8.32} 8.46 65 '}* ~ 64 | 38.7-| 446] .596.| .697 |. .536 | .421 ||12.01 | 12.59 45, 43 31.1 | 37.5 | .692 | .872) .520| .441 1919... {14.62 | 14. 24 37 | 38 | 25.3 | 34.2 | .684 |) .901 | .495 | .463 | '}16.92 | 16.40 | 32 SS [aes 2880, (1741 | 287441) 5485 1): 2400 £. 21.61 |. 22.52) 425.) 24 | 16.0 (23.1) .640 | .960 .446 |. 435 , | b: (A. 51) 4°62 | -120-)5 11 7%e} 44.0]. 43.1 |. .367-|. .368.| .380 | .328 8.48 | 8.48 64 64 34.8 | 39.3 | .544|] .614| .536] .397 1920... 4; 9.84 | 10.40 55 Sar oboe loose ||cisoee 12 736 i) S524. |252408 12.60 | 12.60 | 43 43 | 27.5 | 28.7 | .640 | .668 | .540 | .384 | ~ {18.00 | 18.00 30 30. 19.2 | 27.8 | .640| .927 | .469 . 392 | Number of | Number of earsper | suckers plant. per plant. Single| Pro- |Single| Pro- ear. | lific. | ear. | lific. 0.96 | 1.23 |0 0. 090 15.06) || de 1I= 312.0307 |20 1206" | 1.90" --1*..130' |" -.490 1.62 |.2.36 | .190 | .180 | 1.48 | 2.59- | -260 | .180 1.40 | 3.24 0 . 860 1.108 | 1.656 | .038 | 0 1.333 | 1.975 (0 . 046 | 1.378 | 1.949 | .081 | ..053 1.530 | 2.180 | .031 | .091 1.440 | 2.210 | .042 | 0 97. -|.1.14, |. 083° | * -.026 1.02 1.55 | .031 . 078 OF Mh TSU} |7sQh1y} 2 192 | 1.19 LD Nw LAO - 465 TS) “|P2eaiue las lode |e cos TaBLE 4.—Influence of spacing on yield, weight of ear, and number of ears per plant in single ear and prolific types of corn grown at the Arlington Experiment Farm, Rosslyn, Va., in 1917, 1918, 1919, and 1920.1 Weight of dry ear corn (pounds). of hills. page ne: : = “- | Number occupied Yield Number Number Pa ofplants per plant | ; of ears of suckers S perhill. (square Average | per plant. per plant. yaar | feet). perear. Per hill. | Per plant. : ae | gle | PE | | : 1c. . Ee: Se _Pro- Single Pro- Single Pro- |Single Pro- Single Pro- Single} Pro- Single Pro- a lific.| ear. | lific. | ear. | lific. | ear. lifie. | ear. | lific. | ear. | lific. | ear. | lific. | ae | : 2 20 17 4 4. 2.72; 2.72) 1.720) 1.890) 0.430) 0.472) 0. 454| 0.287) 0.95) 1.65) 0.0120 1917 20 20 3 3} 3.63) 3.63) 1.500] 1.562) .506, .521) .517) .292 96} 1.78 0 0 ; 21 26. 2 2} 5.45) 5.45) 1.362) 1.548) .681, .774) .651} .338) 1.05) 2.29, .095) .019 23 27 1 1) 10. 90) 10.90} .891) .940) .891; .940) .732) .343] 1.21) 2.74) .348) .553 4 30} . 38 4) 4) 2.72| 2.72] .883 1.010] .221, .252)' .268| .241/ .S2| 1.05| .0350 1918 37 38 3 3} 3.63) 3.63) 1017). 977) .339)' -.326; 372) -283 -91) 1.15 0 . 050 : 28 40 2 2; 5.45! 5.45] 1.017) 1.025) .509 513) -. 518 315) .98) 1.62) .035 .100 39 39 df 1, 10.90; 10.90; .813; .920; .813) .920) .773) .421) 1.05) 2.18) .0259 | (37, 29 4 4 2.72 2.72 1.960) 1.960| .490, .490| .475, .304) 1.03] 1.61 .027 138 1919... 33 32 3 3), 3.63) 3.63) 1.770) 1.850) .590) .616}- .590) .331} -1.00) . 1.87) .033) .094 rae: 140 35 2 2) 5.45 5.45) 1.392 1.717| .696) .858) .705) .364) .99) 2.36, 0 0 (38 34 1 1)-10.-90} 10.90) . 728): 1.245) .728| 1.245] .655}. .399} 1.10) 3.12) .05210 | } | 22) 39 4 4, 2.72; 2.72) 1.836} 2,020} .459) .505) .470| .332) . .98} 1.51) .091| .026 = 1990. | 31 34 3 3 3.63, 3.63 1.354 1.620) .451 .540) .483) .326 . 93) 1.66) - £581) 176 36. 39 2 2) 5. 45} + 5. 45) 1..233).1.764| © .617) ..882) .510); .391) 1.21) 2.26) 1.333) .462 . 4 39 1 1) 10.90} 10.90). . 836) 1.253) .836) 1.253) .613) .394| 1.35) 3.18) 1.383 .898 | / | | | - In 1917, 1918, and 1919 the single-ear variety was the Wilson, and in 1920 it was the Delaware White- Cap. Biggs Seven-Ear was the prolific variety used in each of the four years. = 7 7 : i ) end > — .- 8 BULLETIN 1157, U..S. DEPARTMENT OF AGRICULTURE. The data from the experiments at the Arlington Experiment Farm, |} Rosslyn, Va., from 1917 to 1920 are recorded in Table 4. The figures in the columns “Number of plants per hill” represent the actual number in each hill and not a calculated average. In 16 com- parisons the prolific outyielded the single-ear type 14 times and tied once. A comparison of the two types, based on the results obtained at the closest spacing in each experiment, shows that in 12 com- parisons the-single-ear type made the greater gain five times in yield per plant, eleven times in weight of ear, and once in the number of ears per plant. ANALYSIS OF THE YIELDS. A summary of the results of the nine experiments conducted at Clarksdale, San Antonio, and at the Arlington Experiment Farm shows that in a total of 41 comparisons of yield per plant the prolific exceeded the single-ear type 38 times, tied once, and was exceeded twice. In the number of ears per plant the prolific led in every comparison, whereas in the weight of ear the single-ear type led in every comparison. In a total of 32 comparisons the prolific exceeded the single-ear type 22 times in the relative gain in yield per plant, 26 times in the relative gain in number of ears per plant, and 7 times in the relative gain in the weight of ear. Three of the comparisons in which the single-ear type made rela- tively greater gains than the prolific in number of ears per plant and four of the comparisons in which it made relatively smaller gains than the prolific in the weight of ear occurred at San Antonio in 1919. In these experiments the single-ear type showed a marked tendency to produce more than one ear per plant and showed losses in the weight of ear as the spacing increased, producing its heaviest ear at the closest spacing. This was the only instance in the ex- periments that the single-ear type reacted in this manner. The average yield per plant, the weight of ear, and the number of ears per plant of the two types in the nine experiments are given in Table 5. TABLE 5.—Average yield per plant, weight of ear, and number of ears per plant in nine experiments at Clarksdale, Miss., San Antonio, Tex., and Rosslyn, Va. { Weight of ary, ear corn (pound). Nuebae oe e of ears Yield Yield per plant. per plant.) per ear. ST ts ag ep ee ORMRS eet A SR Fret ped Eh MEL cent bid | 0.536 0.514 2 388 1. 04 Prous <5 2 otis wc oat eee c See ee Mek oe ear Ct eee oe eer oceans . 640 5 65 These averages of the results of the nine experiments again indi- cate that an increase in the number of ears per plant has been more effective than an increase in the weight of ear in increasing the yield per plant. Considering the nine experiments as a unit, the yields of both types at each of the first four spacings are compared on a ratio basis — in Table 6. The relative yields within each type at the different spacings are shown in the same table on a basis of 100 for the yields at the closest spacing. INFLUENCE OF SPACING ON PRODUCTIVITY OF CORN. 9 -Tas_e 6.—Ratio of total yields of single-ear and prolific types of corn at each of four spacings on a basis of 100 for the single-ear type and relative yields within each type on = a basis of 100 for the closest spacing, all years and at all stations. q ; awe - F F Relative yields ey Stand Ratio of yields. | vithin gS < ; ' (number %. 1S Spacing. of plants); __ | te peracre.} Single | protific.| Sigle | protific. be ee oe 3 SS a Be Se ee re | 11,820 100 | 110 100 100 EE ee ote sheen ees 8, 523 100 113 | 88 90 Err reas asi eee PS. 2 eet See 6, 034 | 100 132 80 a) no /5 2 ann Soccer ones 3,098 | 100 129 68 | 77 _ The larger yields of the prolific type indicate its better adjustment _ to variations in stand. Both types gave their maximum yields at the closest spacings. As the spacing increases, the yields of the _single-ear type decrease more rapidly than those of the prolific and reach a considerably lower minimum. _ The extreme variation in ear weight and in the number of ears per plant of both types for the nine experiments is shown in Table 7. _ TasLe 7.—Extreme variation in weight of ear and in number of ears per plant in single- ear and prolific types of corn on a basis of 100 for each of the minima. 7 | Weight of ear. | Number of ears per 3 plant. ; Type. re ae Se 2 Minimum. | Maximum. Minimum. Maximum. I — = 2) Se SS See ee 100 289 100 211 ee eae SS ke ES i ag ie a a ee 100 255 | 100 331 _ Tasie 8.—Number of experiments in which the relative gains in the weight of ear either exceed or are less than the relative gains in the number of ears per plant in single-ear and prolific types of corn, showing also the average gains expressed in percentages of the results obtained at the closest spacing. ee, er Number of experiments in| Average gains expressed in which the gainsin the weight | percentages of the results : per ear— | at the closest spacing. Total | a | num- Exceed the | Are less than Single ear. Prolific. a Rate of spacing. ber of gainsin the | the gainsin the : experi- | number of ears number of ears | an Fie ‘ / ments. per plant. per plant. Num- | | Num- 3 . —| Weight! Det Of | weight} Der of Single |p. 4.-, Single | Of ear. ee | of ear. | a ear. |Prolific.| “car. Rane plant. | plant ee ee 9 7 2 2 7 19.4 6.4; 10.1 | 15:0 | eae 19 6 0 2 | 9) 37.2| 17.0) 19.7] 49.8 el ae 9 5 0 | 4 | 9} 52.0) 41.0] 29.3) 79.1 icin SS ees See 4 1 0 3 | 4 21.7 37.5 | 15.2 | 81.5 | 1 The relative gains in the weight of ears and in the number of ears per plant in the single-ear type were equal in one experiment. In the single-ear type there was a greater range in the weight of ear than in the number of ears per plant. In the prolific type the - range of variation was greater in the number of ears per plant than in : 2 10 BULLETIN 1157, U. S. DEPARTMENT OF AGRICULTURE. the weight of ear. The ear showed greater variability in weight i the single-ear type, whereas the number of ears per plant was mor variable in the prolific type. | am In Table 8 the experiments have been classified to show in per centage form the relation of increase in the weight of ear to increas in the number of ears per plant. The percentages are based on th performance of each type at the closest spacing. Im general, the experimental evidence supports the assumptions made earlier in this bulletin as to the reaction of the two types of corn to a better environ- ment. , CONCLUSIONS. In these experiments the prolific type has been more productive than the single-ear type. The prolific type has been more efficient than the single-ear type in increasing the yield per plant and in increasing the number of ears per plant. In increasing the weight of ear the single-ear type has been more efficient. Increasing the number of ears per plant has _ been more effective in increasing the yield per plant than has in- creasing the weight of ear. The experiments indicate that in sections to which both types are adapted the prolific would be the more productive type under the conditions of general field culture because of its better adjustment to varying conditions. ORGANIZATION OF THE U.S. DEPARTMENT OF AGRICULTURE. IIE CROTICIIOUTE =. = =< = a Se in i =e = - Henry C. WALLACE. Fg] a C. W. PuesLey Muenar er aseienijic Work.......2..-:-.------+-- E. D. Batu. mueettor of Heguilatory Work......-..--------.--- SE ee CHARLES F.. Marvin, Chief. Bureau of Agricultural Economics... -.-----.----- Henry C. Taytor, Chief. memraw of Animal Indusiry...-.-.-.-..--------- Joun R. Mouter, Chief. Sumemerge tant Industry. o- -. 2. i. sine n- ese WituraM A. Taytor, Chief. DS Spo: SS Se ee W. B. GREELEY, Chief. eg ee WaLTER G. CAMPBELL, Acting | Chief. Se Mitton Wuaitney, Chief. Bere OF Piniomelogy..---. 352: .5....----+.---- L. O. Howarp, Chief. | Bureau of Biological Survey........-.------------ E. W. Nexson, Chief. men, Of Puvise Roads: .-...--...+-2---.----- Tomas H. MacDonatp, Chief. _ Fixed Nitrogen Research Laboratory........------ F. G. Cotrrett, Director. | Division of Accounts and Disbursements...-...~.--- A. ZAPPoNneE, Chief. SmI OPP OUICOLONS >. 225521222... see ee Epwin C. PowEtL, Acting Chief. Sic gg Ts 2 oS ge CLARIBEL R, BarNneEtt,Librarian. musiaies Relations Service. .-.2.--/-...------...--. A.C. True, Director. Rumer t70rineriural board... -5.-.-..2.-.----<- C. L. Maruatt, Chairman. Insecticide and Fungicide Board................. J. K. Haywoon, Chairman. Packers and Stockyards Administration.......--..-- yee MorrILu, Assistant to the Grain Future Trading Act Administration......-.-. Secretary. OLED ROT) 1 i ae R. W. Wiitrams, Solicitor. This bulletin is a contribution from Ce CT PUMP ROUSI . «So. osc ccd cece nse a Witiram A. Taytor, Chief. Office of Cereal Investigations........-------- CaRLETON R. Batt, Cerealist in Charge. ll ADDITIONAL COPIES OF THIS PUBLICATION MAY BE PROCURED FROM THE SUPERINTENDENT OF DOCUMENTS GOVERNMENT PRINTING OFFICE WASHINGTON, D. C. AT 5 CENTS PER COPY PURCHASER AGREES NOT TO RESELL OR DISTRIBUTE THIS COPY FOR PROFIT.—PUB. RES. 57, APPROVED MAY II, 1922 A