UNIVERSITY OF CALIFORNIA COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA Crown-Grading Experiments With Asparagus H. A. JONES and G. C. HANNA BULLETIN 633 January, 1940 UNIVERSITY OF CALIFORNIA BERKELEY, CALIFORNIA CONTENTS PAGE Introduction 3 The production of spears 4 Yield of spears per acre 5 Yield of spears per plant 7 Number of spears harvested per plant 7 Mean weight of spear 9 Size grades of spears 10 The production of stalks 11 Weight of stalks per acre 11 Weight of stalks per plant 13 Mean number of stalks per plant 14 Mean weight of stalks 15 Summary 15 CROWN-GRADING EXPERIMENTS WITH ASPARAGUS 1 H. A. JONES 2 and G. C. HANNA 3 INTRODUCTION Growers of asparagus have often debated the value of sorting the crowns according to size and planting only the larger ones. Although the results of previous experimental work have been rather meager, those reported seem to indicate that crown selection is beneficial. Myers 4 in Pennsylvania conducted crown-grading experiments with the varieties Palmetto and Argenteuil. In the spring of 1908, one-year- old crowns were divided into three size grades and planted. The plots were cut for the first time in 1910. Apparently there was no significant difference in yield between the no. 1 (or large) size and the no. 2 crowns. In no case, however, did the no. 3 (or small) crowns produce so much as the other two grades, even after six years. To secure experimental data for California, crown-grading studies were conducted at Davis over several years with the varieties Palmetto and Mary Washington. Crowns grown at the University Farm in 1923 were dug in January and February, 1924. Within a few days these were separated into three grades, according to size, and planted. The mean weights per crown of grade nos. 1, 2, and 3 of Palmetto were 0.49, 0.22, and 0.09 pound; of Mary Washington, 0.38, 0.16, and 0.07 pound respec- tively. Since the seedlings were not spaced in the nursery, the differences in size of crown were caused by variation in spacing, by other environ- mental factors, and by heredity. The crowns were set 8 inches deep and spaced 2 feet apart in rows 7% feet apart. Plots consisted of single rows 236% feet long, extending east and west, and were planted in triplicate. Since, however, early in the life of the bed, the soil in one replicate proved very unsatisfactory for as- paragus, the crop was plowed up ; hence the data presented are for dupli- cate plots only. In the statistical analysis as applied in this paper, 2 x S. E. of a differ- 1 Received for publication August 31, 1939. 2 Professor of Truck Crops and Olericulturist in the Experiment Station. Re- signed July 1, 1936. 3 Associate in Truck Crops. 4 Myers, C. E. Experiments with asparagus. Pennsylvania State College Ann. Rept. 1915-16:557-78. 1918. [3] 4 University of California — Experiment Station ence has been taken as the limit of experimental variability ; differences between means that exceed this are considered significant. The time of first irrigation each year varied somewhat with the amount of winter rainfall ; during the summer the field was surface-irrigated whenever it was considered necessary. A heavy irrigation was always given immediately after the cutting season to help insure a good growth of "fern." The last application of water came usually about the first of September. About 15 tons of barnyard manure was applied to the acre each fall except in 1933 and 1934. The field was then plowed or disked to form ridges of soil over the rows and to facilitate rotting of the manure and stubble during the winter. In preparation for the cutting season the ridges were disked down, and then rebuilt to mark the rows for the cut- ters and to facilitate irrigation. On the last harvest day each year the ridges over the rows were again disked down to kill weeds and to loosen the soil packed by heavy rains and by the walking of the cutter ; they were then rebuilt. THE PRODUCTION OF SPEARS The plots were first cut in the spring of 1925 ; and harvesting was con- tinued for twelve years, which is approximately the commercial life of an asparagus bed in California. From year to year the date of the first cutting varied somewhat with climatic conditions, but it was usually in late February or early March. The date of the last cutting for each season was as follows : 1925, April 13 ; 1926, April 25 ; 1927 and 1928, May 15 ; 1929, 1930, and 1931, May 20; 1932, May 28; 1933, May 24; 1934, May 10 ; and for 1935 and 1936, May 20. The date of the last cutting each year was determined by the general response of the bed and by the appearance of the spears toward the end of the season. An effort was made to stop cutting while the fleshy roots contained a sufficiently large reserve of plant food to insure a rapid and heavy top growth immediately after the harvest. The plots were harvested once each day throughout the cutting season except early in the year, when growth was slow because of low tempera- tures. The only spears cut were those l 1 ^ inches or more above the ground. The spears were cut long enough in the field to be trimmed later to a uniform length of 8% inches. All yield and weight records were based on spears 8% inches long. Spears too spindly to be included in the usual small grade of the fresh pack and spears very crooked and otherwise mis- shapen were not weighed, but at each harvest were cut and left lying in the field. Bul. 633] Crown-Grading Experiments with Asparagus 5 Yield of Spears Per Acre. — The yield of spears per acre (table 1) for both Palmetto and Mary Washington increased each consecutive year for the first seven cutting seasons. The highest yields were secured in 1931, the seventh harvest season, when all yields were over 10,000 pounds per acre. One should not infer that the peak yield is always to be expected on a bed eight years of age, but this age is perhaps the most productive from the standpoint of marketable spears. Although the yields after 1931 fluctuated somewhat, they were always below the 1931 peak. TABLE 1 Mean Yield of Spears from Three Size Grades of in Pounds per Acre* Crowns, Year Palmetto Mary Washington No. 1 No. 2 No. 3 No. 1 No. 2 No. 3 1925 1926 590 2,482 4,195 5,024 6,653 6,756 10,436 9,117 8,205 7,918 7,635 9,362 6,531 510 2,465 3,990 4,778 6,670 6,644 10,362 8,752 7,928 7,788 7,774 9,067 6,394 454 2,120 3,649 4,764 6,338 6,601 10,143 9,178 8,303 8,044 8,023 9,500 6,426 712 2,670 4,446 5,352 7,298 7,269 10,638 9,266 8,520 8,097 7,994 9,553 6,818 672 2,185 3,922 ,4,937 6,527 7,020 10,250 8,994 8,394 8,278 8,420 9,569 6,597 586 2,146 1927 1928 3,738 4,795 1929 6,366 1930 6,798 1931 10,108 1932 1933 1934 1935 8,692 7,592 7,702 7,858 1936 8,878 6,272 * Differences between means of duplicate plots in the table must exceed 538 pounds to be significant. This value can be used to compare years, grades, or varieties. t To be significant, differences between the means for the 12 years must exceed 155 pounds. The means of the twelve years for the Palmetto variety showed no sig- nificant difference in yield between the three grades of crowns. If, how- ever, we consider the means of only the first seven cutting seasons, then the no. 1 crowns outyielded the no. 3 by a mean of 295 pounds per acre, a difference of 203 pounds being required for significance. For the seven- year period the no. 1 crowns outyielded the no. 3 by a total of 2,067 pounds. The mean yields of the no. 1 and no. 2 crowns did not differ significantly up to the end of the seventh harvest season. Judging from the first seven years' data alone, it would seem advisable not to plant the no. 3 crowns even though the latter finally did catch up with the other two grades in total production. According to the means of the twelve years for the Mary Washington variety, the no. 1 and no. 2 crowns outyielded the no. 3 by 546 and 325 pounds per acre, respectively, a difference of only 155 pounds being re- 6 University of California — Experiment Station quired for significance. In total production the no. 1 and no. 2 crowns exceeded the no. 3 by 6,558 and 3,906 pounds. The data apparently indi- cate that with this variety, too, it would be profitable to discard rather than plant the smallest grade of crowns. The no. 1 crowns also outyielded the no. 2 by a mean of 221, or a total of 2,652 pounds for the twelve years. The three grades of crowns held their relative positions in production during the first nine cutting seasons. In the last three cutting seasons TABLE 2 Mean Yield of Spears from Three Size Grades of Crowns, in Pounds per Plant* Year Palmetto Mary Washington No. 1 No. 2 No. 3 No. 1 No. 2 No. 3 1925 0.20 0.86 1.45 1.74 2.30 2.33 3.60 3.14 2.83 2.74 2.64 3.23 2.26 0.18 0.85 1.38 1.65 2.30 2.30 3.58 3.02 2.74 2.68 2.68 3.12 2.21 0.16 0.74 1.26 1.64 2.18 2.28 3.50 3.16 2.86 2.78 2.76 3.28 2.22 0.24 0.92 1.54 1.84 2.52 2.50 3.67 3.20 2.94 2.80 2.76 3.30 2.35 0.24 0.76 1.36 1.70 2.25 2.42 3.54 3.10 2.90 2.86 2.90 3.30 2.28 0.20 1926 0.74 1927 1.29 1928 1.66 1929 2.20 1930 1931 2.34 3.48 1932 1933 1934 1935 1936 Mean\ 3.09 2.62 2.66 2.71 3.06 2.16 * Difference required for significance between one-year means, 0.18 pound, t Difference required for significance between twelve-year means, 0.05 pound. the no. 2 crowns produced slightly more than no. 1 ; no. 3, however, was lowest each year. When the data are studied by the analysis-of- variance method, the high values secured for grades show odds of more than 99 to 1 that the differences secured do not result from chance alone. To compare the production of the two varieties, the yields of the three crown grades of each variety were averaged and are presented in table 5. Mary Washington produced a slightly heavier yield than Palmetto in ten years out of the twelve, though the yearly differences were too small to be significant except in 1930. The means for the twelve years, however, show that Mary Washington outyielded Palmetto an average of 112 pounds a year, while a difference of only 90 pounds is required for sig- nificance. According to variance analysis, the difference in yield between the two varieties is significant but not highly so. A higher percentage of the spears of Mary Washington fall, however, into the larger size grades, which are more valuable. Bul. 633] Crown-Grading Experiments with Asparagus 7 Yield of Spears per Plant. — As the yields per plant are calculated from the same data as the yields per acre, they might be expected to parallel each other closely (table 2). The peak year was reached in 1931 with a yield of more than 3.5 pounds per plant. The means for the twelve years in the variety Palmetto showed no significant difference in yield between the three grades of crowns. The means for the first seven years, however, showed that the no. 1 and no. 2 crowns had produced signifi- TABLE 3 Mean Number of Spears Produced per Plant from Three Size G-rades of Crowns* Year Palmetto Mary Washington No. 1 No. 2 No. 3 No. 1 No. 2 No. 3 1925 5.2 15.2 22.1 27.0 31.8 38.8 56.8 54.6 51.1 53.0 46.2 65.6 89.0 4.8 15.6 21.7 25.8 32.1 38.4 59.6 56.6 53.6 55.5 50.4 67.4 40.1 4.3 13.7 20.3 26.1 30.5 37.8 56.8 57.2 52.2 54.4 49.8 68.3 39.3 4.8 13.0 19.9 23.6 29.2 34.6 50.0 49.5 47.0 47.8 44.1 60.5 35.3 4.4 11.0 18.2 22.8 28.0 34.0 49.2 49.6 46.4 49.4 41.9 61.2 84.7 4.0 1926 10.2 1927 16.0 1928 20.5 1929 25.1 1930 30.8 1931 46.6 1932 44.8 1933 50.0 1934 45.0 1935 42.3 1936 56.7 32.7 * Difference required for significance between one-year means, 4.89 spears, t Difference required for significance between twelve-year means, 1.41 spears. cantly more than the no. 3. For the variety Mary Washington, the mean for the twelve-year period shows that the no. 1 crowns yielded best and the no. 3 poorest, with a significant difference between the three grades of crowns. Variance analysis revealed a highly significant difference be- tween crown grades. The mean yields per plant of the two varieties are compared in table 5, where the three grades of each variety have been averaged. Mary Wash- ington yielded slightly more in pounds per plant than Palmetto except in 1926, 1931, and 1932. The twelve-year mean for Palmetto was 2.23 pounds to the plant; for Mary Washington 2.26. A difference of 0.03 pound is required for significance. By variance analysis, the difference due to varieties is significant but not highly so. Number of Spears Harvested per Plant. — For both varieties and for all grades of crowns there was in a general a significant increase in the number of spears produced per plant (table 3) each consecutive year 8 University of California — Experiment Station until 1931, the seventh cutting season, after which there was a leveling off until 1936, when more spears were produced per plant than in any preceding year. Although the largest number of spears were harvested per plant in 1936, the yield was much below the peak year of 1931 because of the smaller size of spear. The means of the twelve years for the Palmetto variety (table 3) reveal no significant difference in number of spears produced by the different TABLE 4 Mean Weight, in Grams, of Single Spears from Three Size Grades of Crowns* Year Palmetto Mary Washington No. 1 No. 2 No. 3 No. 1 No. 2 No. 3 1925 17.8 25.5 29.7 29.0 32.6 27.1 28.8 26.2 25.1 23.2 25.8 22.4 26.1 16.8 24.7 28.8 28.9 32.6 27.0 27.2 24.2 23.2 22.0 24.2 21.1 25.0 16.4 24.2 28.2 28.6 32.6 27.4 28.0 25.2 24.9 23.2 25.2 21.8 25.5 23.6 32.1 34.8 35.4 39.0 32.7 33.2 29.3 28.4 26.4 28.3 24.7 30.7 23.9 31.2 24.0 33.9 36.6 32.3 32.8 28.5 28.5 26.4 28.8 24.6 80.1 22.8 1926 33.0 1927 37.0 1928 36.8 1929 39.9 1930 34.8 1931 34.1 1932 30.4 1933 28.5 1934 26.8 1935 29.2 1936 24.6 81.5 * Difference required for significance between one-year means, 1.41 grams, t Difference required for significance between twelve-year means, 0.41 gram. grades of crowns. For Mary Washington, crown grades no. 1 and no. 2 each produced significantly more spears than no. 3. By variance analysis the difference in number of spears harvested per plant due to size grades of crowns was significant but not highly so. The two varieties were compared as to number of spears per plant by averaging the three crown grades for each variety. Except in 1925, as shown by the data in table 5, Mary Washington produced significantly fewer spears every season than Palmetto. For the twelve-year period the Palmetto produced a mean of 39.5 spears per plant, the Mary Washing- ton 34.2, a difference of 5.3 spears, whereas a difference of only 0.81 spear is required for significance. According to variance analysis the odds are more than 99 to 1 that the difference between these two varieties in num- ber of spears harvested per plant does not result from chance alone. The high value for varieties when compared with interactions involving varieties shows that the difference between varieties in number of spears was highly consistent. Bul. 633] Crown-Grading Experiments with Asparagus 9 Mean Weight of Spear. — The mean weight of spear for both varieties increased until the fifth cutting season (table 4) , after which there was a somewhat irregular decline, probably because of seasonal conditions and not because of irregular behavior of the plants. In Palmetto the largest spears were produced by the no. 1 crowns, the smallest by the no. 2, and the difference between the means of twelve years was significant. For Mary "Washington the largest spears were TABLE 5 Comparison of Palmetto and Mary Washington Varieties of Asparagus in Spear Production Year Yield of spears, in pounds per acre Yield of spears, in pounds per plant Number of spears harvested per plant Mean weight of single spear, in grams Palmetto Mary- Washing- ton Palmetto Mary- Washing- ton Palmetto Mary Washing- ton Palmetto Mary Washing- ton 1925 518 2,356 3,945 4,855 6,554 6,667 10,314 9,016 8,145 7,917 7,811 9,310 6,450 657 2,334 4,035 5,028 6,730 7,029 10,332 8,984 8,169 8,026 8,091 9,333 6,562 0.18 0.82 1.36 1.68 2.26 2.30 3.56 3.11 2.81 2.73 2.69 3.21 2.23 0.23 0.81 1.40 1.73 2.32 2.42 3.56 3.10 2.82 2.77 2.79 3.22 2.26 4.8 14.8 21.4 26.3 31.5 38.3 57.7 56.1 52.3 54.3 48.8 67.1 39.5 4.4 11.4 18.0 22.3 27.4 33.1 48.6 48.0 47.8 47.4 42.8 59.5 34-2 17.0 24.8 28.9 28.8 32.6 27.2 28.0 25.2 24.4 22.8 25.1 21.8 25.6 23.4 1926 32.1 1927 35.3 1928 35.4 1929 38.5 1930 33.3 1931 33.4 1932 29.4 1933 28.5 1934 26.5 1935 28.8 1936 24.6 30.8 Differences re- quired for signif- icance between varieties 311 0.10 2.82 0.82 Differences re- quired for signif- icance between means of varieties 90 0.03 0.81 0.66 produced by the no. 3 crowns, the smallest by the no. 2. Though variance analysis shows a highly significant difference in size of spear between crown grades, large spears were not associated with any definite crown grade. The two varieties were compared as to mean weight of spear by aver- aging the three crown grades for each variety. The data are presented in table 5. As variance analysis shows, the spear weight for Mary Washing- ton was significantly higher than for Palmetto every year. For the 10 University of California — Experiment Station twelve-year period, Palmetto spears weighed 25.6 grams, Mary Wash- ington 30.8, a difference of 5.2, whereas only 0.66 gram is required for significance. An analysis of table 5 shows the difference in spear size between varieties to be highly consistent. TABLE 6 Distribution of Spears in Different Size Grades, Grown from Three Size Grades of Crowns ; 1928 Variety and crown grade Per cent spears in the following size grades: Under Z A in, to H inch ^AtoYz inch 5 Ato% inch Over % inch Palmetto \ 2 Mary I 1 Washington -j 2 3 10.29 9.47 3.87 5.72 4.53 37.58 38.57 39.40 25.49 29.48 24.73 34.27 35.45 34.73 37.73 35.23 34.94 16.10 15.54 14.50 26.91 24.28 27.50 1.77 0.97 1.51 6.00 5.30 8.30 Size Grades of Spears. — In 1928 the spears harvested from the three grades of crowns for both Palmetto and Mary Washington were sorted into five sizes (table 6). The diameter of the spears was measured 5% inches from the tip ; and each day's harvest was trimmed, graded, and TABLE 7 Yield of Different Size Grades of Spears, Grown from Three Size Grades of Crowns ; 1928 Pounds of spears per acre in the following size grades: Differences required for sig- nificance Variety and crown grade Under %inch % to y 2 inch V2toy s inch ^toM inch Over % inch f« Palmetto < 2 Is 517 452 470 480 207 282 217 235 1,888 1,843 1,877 1,869 1,364 1,455 1,186 1,335 1,722 1,694 1,654 1,690 2,019 1,739 1,675 1,811 809 742 691 747 1,440 1,199 1,318 1,319 89 46 72 69 321 262 398 327 246 246 246 142 246 Washington j 2 13 246 246 142 weighed. Grading was continued throughout the season. The percentage by weight of the different size grades appears in table 6. Palmetto had a much higher percentage of its crop in the grades under ^ inch in diam- eter than did Mary Washington. The two varieties differed very little in the percentage of the crop falling into the 1 / 4-to-%-inch grade ; but in the grades above % inch Mary Washington had a much higher percentage Bul. 633] Crown-Grading Experiments with Asparagus 11 than Palmetto. These differences would account for the larger mean weight per spear for Mary Washington. Table 7 gives the yield in pounds per acre of the different size grades of spears for crown grades nos. 1, 2, and 3. For Palmetto there was no significant difference between the no. 1, 2, and 3 crowns for any size grade of spear. In Mary Washington there were significant differences between the no. 2 and 3 crown grades in the spear size % to % inch and between crown grades nos. 1 and 3 in spear size % to % inch. In each instance the larger crowns gave the heavier yield. Mary Washington and Palmetto can be compared as to distribution of size grades of spears by averaging the yields of the no. 1, 2, and 3 crowns of each variety (table 7). In the spear size under % inch in diameter Mary Washington produced 245 pounds less than Palmetto ; in spear size % to % inch in diameter, 534 pounds less. Mary Washington produced 121 pounds more than Palmetto in the V 2 -to-%-inch size, 572 pounds more in the %-to-%-inch size, and 258 pounds more of spears over % inch in diameter. In other words Palmetto produced 779 pounds per acre more than Mary Washington in spear sizes below % inch in diameter, while Mary Washington produced 951 pounds more than Pal- metto in spear sizes above % inch. Variance analysis showed odds of more than 99 to 1 that the differences in the size grades of spears between varieties did not result from chance alone. THE PRODUCTION OF STALKS In addition to a record of spear production, data were kept of the weight and the number of stalks produced by the different crown grades. The stalks were cut and weighed each year about the middle of October while they were still green. All plots were cut and weighed on the same day. Though the tops could not be harvested at exactly the same stage of maturity each year, an attempt was made to get weights before any of the foliage began to fall. When dry the tops were burned except in 1933 and 1934, when they were chopped by machine and then plowed under. Weights were secured each year from 1924 to 1930 and again in 1932. Although, in good commercial practice, the stalks should probably not be cut while still green, such cutting was the only practical means of obtaining comparative top yields. The plants in the experiment were probably not injured appreciably by this early destruction of the tops. The number of stalks was determined, as a rule, by counting the stubs after cutting the tops. Weight of Stalks per Acre. — The yield of green tops per acre was very low in 1924, the year the crowns were set (table 8). Although the yield 12 University of California — Experiment Station of tops increased every year till 1929, the increase between consecutive years was not always significant. In both Palmetto and Mary Washing- ton the means for the eight years show that the no. 1 crowns produced a significantly heavier yield of tops than the no. 3, whereas the no. 2 TABLE 8 Tons of Green Stalks per Acre Produced from Three Size Grades of Crowns* Year Palmetto Mary Washington No. 1 No. 2 No. 3 No. 1 No. 2 No. 3 1924 1.46 4.32 4.78 5.34 6.10 7.62 8.42 8.60 5.83 1.17 3.80 4.46 5.21 6.30 8.00 7.50 8.19 5.57 0.98 3.38 4.02 4.74 5.73 7.68 7.20 8.52 5.28 1.25 3.70 4.52 5.69 6.44 8.80 8.06 8.30 5.84 1.10 3.24 4.16 5.10 6.40 8.48 8.48 8.90 5.73 0.96 1925 2.94 1926 3.98 1927 4.96 1928 5.49 1929 8.88 1930 1932 8.31 8.40 5.48 * Difference required for significance between one-year means, 0.85 ton. t Difference required for significance between eight-year means, 0.30 ton. crowns took an intermediate position. By variance analysis the differ- ences in weight of tops due to crown grades are highly significant, the odds being more than 99 to 1 that they did not result from chance alone. TABLE 9 Mean Weight, in Pounds, of Stalks per Plant from Three Size Grades of Crowns* Year Palmetto Mary Washington No. 1 No. 2 No. 3 No. 1 No. 2 No. 3 1924 1.00 2.98 3.30 3.69 4.22 5.26 5.82 5.93 4.02 0.80 2.62 3.07 3.60 4.34 5.52 5.17 5.65 3.85 0.67 2.33 2.78 3.26 3.96 5.30 4.97 5.88 3.64 0.87 2.55 3.12 3.93 4.45 6.07 5.56 5.74 4-04 0.76 2.23 2.87 3.52 4.42 5.86 5.86 6.14 3.96 0.66 1925 2.02 1926 2.68 1927 3.42 1928 3.78 1929 6.13 1930 5.73 1932 5.80 3.78 * Difference required for significance between one-year means, 0.58 pound, t Difference required for significance between eight-year means, 0.21 pound. The weights of tops of the three crown grades for each variety were averaged to permit comparison of the two varieties (table 12) . The yield of stalks of the two varieties differed very little from year to year. For Palmetto the mean production for the eight years was 5.56 tons, for Mary Bul. 633] Crown-Grading Experiments with Asparagus 13 Washington 5.68, a difference of only 0.12 ton, whereas a difference of 0.17 ton is required for significance. Weight of Stalks per Plant. — As might be expected, the results for TABLE 10 Mean Number of Stalks per Plant from Three Size Grades of Crowns* Palmetto Mary Washington No. 1 No. 2 No. 3 No. 1 No. 2 No. 3 1924 9.1 8.2 7.9 9.0 11.1 12.6 12.4 14.8 15.1 19.6 15.9 15.8 12.6 8.9 7.8 7.8 8.8 12.0 14.6 12.9 16.1 17.2 20.4 17.7 16.8 is. 4 8.8 7.6 7.0 9.1 10.3 12.8 12.2 14.9 16.4 20.6 17.6 16.0 12.8 7.0 5.8 6.5 8.2 9.6 11.1 10.8 13.6 14.2 19.0 16.7 16.6 11.6 7.2 5 3 5.6 7.8 10.0 13.6 11.9 15.3 15.7 19.0 17.6 17.1 12.2 7 1925 4.8 1926 5.6 1927 7.4 1928 1929 8.4 11.5 1930 9.2 1931 12.6 1932 12.7 1933 17.2 1934 16.0 1935 16.9 10.8 * Difference required for significance between one-year means, 2.39 stalks, t Difference required for significance between twelve-year means, 0.69 stalk. yield of stalks per plant closely paralleled those for yield per acre (table 9). The mean yield of stalks per plant (table 12) for Palmetto for the eight-year period was 3.84 pounds, for Mary Washington 3.92 pounds, TABLE 11 Mean Weight, in Pounds, of Single Stalks from Three Size Grades of Crowns* Year Palmetto Mary Washington No. 1 No. 2 No. 3 No. 1 No. 2 No. 3 1924 0.110 .366 .417 .422 .380 .420 .470 0.393 0.872 0.091 .335 .398 .408 .363 .380 .416 0.337 0.341 0.076 .308 .400 .358 .384 .416 .408 0.369 0.840 0.122 .449 .481 .478 .462 .550 .520 0.404 0.438 0.106 .422 .506 .456 .452 .431 .499 0.393 0.408 0.093 1925 .426 1926 .480 1927 .466 1928 .447 1929 .530 1930 .631 1932. . 0.456 0.441 * Difference required for significance between one-year means, 0.10 pound, t Difference required for significance between eight-year means, 0.04 pound. a difference of 0.08 pound, whereas a difference of 0.12 pound is required for significance. By variance analysis, differences caused by crown grades were highly significant, whereas those caused by varieties were not. 14 University of California — Experiment Station Mean Number of Stalks per Plant. — The number of stalks produced per plant after the cutting season was determined every year from 1924 to 1935 ; a record is given in table 10. In general there was very little difference in the number of stalks produced during the first four years, but thereafter a gradual increase occurred until 1933. The environ- mental conditions seemed to influence the two varieties similarly. An increase or decrease in the number of stalks was reflected about the same TABLE 12 Comparison of Palmetto and Mary Washington Varieties of Asparagus in Stalk Production Yield of stalks, in tons per acre Yield of stalks, in pounds per plant Number of stalks produced per plant Mean weight of single stalk, in pound Year Palmetto Mary Washing- ton Palmetto Mary Washing- ton Palmetto Mary Washing- ton Palmetto Mary Washing- ton 1924 1.20 3.83 4.42 5.10 6.04 7.77 7.71 8.44 5.56 1.10 3.29 4.19 5.25 6.11 8.72 8.28 8.53 5.68 0.82 2.64 3.05 3.52 4.17 5.36 5.32 5.82 3.84 0.76 2.27 2.89 3.62 4.22 6.02 5.72 5.89 3.92 8.9 7.9 7.6 9.0 11.1 13.3 12.5 15.3 16.2 20.2 17.1 16.2 12.9 7.1 5.3 5.9 7.8 9.3 12.1 10.6 13.8 14.2 18.4 16.8 16.9 11.5 0.092 .336 .405 .396 .376 .405 .431 0.366 0.851 0.107 1925 .432 1926 .489 1927 .467 1928 .454 1929 .504 1930 .550 1931 1932 0.418 1933 1934 1935 0.428 Differences re- quired for signif- icance between varieties 0.49 0.34 1.38 0.060 Differences re- quired for signif- icance between means of varieties 0.17 0.12 0.34 0.020 in both varieties. Each had peak numbers in 1933, followed by a decline in 1934 and 1935. The means for the twelve-year period show that the no. 2 crowns of Palmetto produced significantly more stalks than the no. 1 and in Mary Washington the no. 2 crowns produced significantly more stalks than the no. 3. In both varieties the no. 2 crowns produced the most stalks. By variance analysis, the difference in number of stalks per plant be- tween crown grades was highly significant; but there is evidently no constant association between crown grade and number of stalks per Bul. 633] Crown-Grading Experiments with Asparagus 15 plant, because the smallest number was produced in Palmetto by the no. 1 crowns and in Mary Washington by the no. 3. If the two varieties are compared by years (table 12) , Mary Washing- ton is seen to have produced fewer stalks than Palmetto in every year except 1935. The mean number of stalks produced per plant by Palmetto for the twelve-year period was 12.9, for Mary Washington 11.5, a differ- ence of 1.4, whereas a difference of only 0.34 stalk is required for sig- nificance. When studied by variance analysis, the difference in number of stalks between varieties is highly significant, and the difference in number of stalks between the two varieties is highly consistent and might be ex- pected to occur rather generally. Mean Weight of Stalks. — The mean weight of the individual stalks increased from 1924 to 1926, after which there was considerable fluctua- tion from year to year (table 11). Variance analysis reveals no signifi- cant difference in weight of stalk between crown grades. The data presented in table 12 show that every year the mean weight of the individual Mary Washington stalks was highest. Thus the greater weight of the spear of Mary Washington was projected into the mature stalk. The mean weight of the stalk for the eight-year period in which weights were made was 0.351 pound for Palmetto, 0.428 for Mary Wash- ington, a difference of 0.077 pound, whereas a difference of only 0.020 pound is necessary for significance. SUMMARY Crown-grading tests were run at Davis, California, from 1925 to 1936 on the Palmetto and Mary Washington varieties of asparagus. One-year- old crowns of each variety were segregated into three size groups at the time of planting. Data were collected on the production of both spears and stalks. The mean yield of spears for the first seven cutting seasons of the variety Palmetto showed that the no. 1 or large crowns significantly out- yielded the no. 3. In Mary Washington the mean yields for the twelve cutting seasons showed that the no. 1 and no. 2 crowns significantly out- yielded the no. 3. The significantly higher yields of spears in favor of the larger crowns indicate the desirability of discarding the small crowns. Over the twelve-year period the Mary Washington variety produced more heavily than the Palmetto. There was no significant difference between crown grades in the mean number of spears harvested per plant for Palmetto over the twelve-year period. In Mary Washington, however, crown grades nos. 1 and 2 pro- 16 University of California — Experiment Station duced significantly more spears than no. 3. Palmetto produced a mean of 5.3 more spears per plant than Mary Washington, a highly significant difference. There appeared to be no relation between size of crown planted and weight of spear. The mean weight of spear for Mary Washington was 5.2 grams greater than for Palmetto, a highly significant difference. When spears were sorted into various size grades, a greater percent- age by weight of Mary Washington than Palmetto fell into the larger grades. In both Palmetto and Mary Washington the no. 1 crowns produced a significantly heavier yield of stalks than crown grade no. 3. The no. 2 crowns for both varieties took an intermediate position. In total yield of stalks the two varieties produced about alike. The size of crown appears to bear no relation to the mean number of stalks per plant in either variety. Mary Washington produced a mean of 1.4 fewer stalks per plant than Palmetto, a highly significant difference. 10m-3, '40(2435)