EFFECT OF SEED SIZE AND DEPTH OF PLANTING ON

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1 ALAM AND LOCASCIO: BROCCOLI-BEAN STUDIES 107 EFFECT OF SEED SIZE AND DEPTH OF PLANTING ON BROCCOLI AND BEANS1 Z. Alam and S. J. Locascio2 The quality of seed planted is universally recognized to be of major importance in success ful crop production. However, the relationship between size of seed planted and planting depth on the characteristics of the developing plant is less apparent. The relation of size of seed planted to various aspects of plant growth has been studied by a number of workers. With sweet corn, Cameron, et al., (3) found that the number of large plants from large seed was nearly always greater than from smaller seed. By harvest time, differences were still significant in terms of earliness. Hoff man (5) and Schmidt (14) found that large corn seed produced greater yield than small seed. Kisselbach (7) summarized all available pub lished data in his work on grains. He reported that seedlings from small seed usually showed lower vigor and sometimes yielded as much as 18 percent less than large seed over seed unsorted for size. Wester and Magruder (17) did not find any effect of seed size on percent germination of Baby Fordhook bush lima beans, but large seed produced significantly heavier seedlings and higher yields than smaller seeds (18). Rudolfs (13) obtained similar results with beans. Re cently Tompkins (16) found that in broccoli more plants matured earlier from large seeds than from small seeds and had substantially higher early yields of center heads. Transplants grown from graded seed were more uniform and needed less labor for sorting before transplanting. Other workers have also studied the effects of seed size (1, 2, 4, 11) mostly with agronomic crops. Germination rate and plant vigor were found to be reduced as the planting depth in creased (8, 10). The purpose of this investigation was to study the effect of seed size and depth of planting on growth and yield of broccoli and beans. Experimental Procedure Greenhouse experiments were initiated in January, 1965 at Gainesville. Later in the spring, iflorida Agricultural Experiment Stations, Journal Series No Research Assistant and Associate Horticulturist, Vege table Crops Department. Florida Institute of Food and Agri cultural Sciences. Gainesville, Florida. studies were continued under field conditions. Two kinds of vegetables, Waltham 29 broccoli and Contender beans, were included in the studies. In the greenhouse studies a 3 x 4 factorial with four replications was used in a randomized block design. The factors were three seed sizeslarge, medium and small, and, four planting depths,,, and inches. A Kanapaha fine sandy soil was placed in a bench to a depth of 6 inches, and fertilizer was broadcast at the rate of 1,000 pounds per acre of s of these crops were planted in rows feet long and foot apart. Accurate depth of seeding was accomplished by use of wooden boards feet in length with thickness corresponding to the planting depth. These were pressed into the soil to their respective depths. Broccoli seeds were spaced 2 inches apart, while beans were placed 3 inches apart. were covered with the bedding soil, and the soil was slightly packed. Soil moisture was kept near optimum during the experiment by watering with a fine sprinkler. Air temperature was main tained between 60 F. and 80 F. was separated into three sizes by screen ing through sieves. Five samples of 100 seed of each size ranged in weight as follows: broccoli, large seed from 0.60 to 0.70 grams, medium 0.45 to 6 grams, and small 0.30 to 0.40 grams. Large bean seed samples weighed from 64.8 to 66.3 grams, medium 47.8 to 49.5 grams, and small 29.0 to 32.2 grams. In the field studies, a 3 x 3 factorial with five replications was used for each crop. The factors were used size large, medium and small, and, planting depth,, and inches. Soil used was a Kanapaha fine sand. Treatments were arranged in single row plots 20 feet long and 3 feet apart. Fertilizer was banded to the side of the seed at planting time at the rate of 700 pounds per acre of s were drilled on a well prepared soil using a Planet Jr. garden seeder. Planting depths were obtained by adjust ment of the planting shoe. Immediately after seeding, each crop was irrigated lightly with an overhead sprinkler system. Thereafter, irriga tion and other cultural operations, such as weed ing, hoeing, side-dressing and pesticides were given as needed.

2 108 FLORIDA STATE HORTICULTURAL SOCIETY, 1965 Broccoli was direct seeded on February 5, After germination, plants were thinned to feet apart. At harvest, on May 11, 1965, very few heads had formed; therefore, instead of recording head weights, fresh weight of ten randomly selected plants in each treatment was recorded. Beans were seeded on April 16, 1965, on raised beds. After germination, plants were spaced 4 inches apart. Harvesting was accom plished on June 8, Similar studies were also conducted with sweet corn and watermelons which will be pub lished later. Results Broccoli: The effects of seed sizes and depths TABLE 1. Effect of seed size and depth of planting on rate.of emergence, percent germination, plant height and fresh weight of "broccoli in greenhouse and field studies1. OffiENHOUSE I 3T0DY FIELD Size Depth Inches 8 Days 10 Germinatioi 1 percent after 12 seeding Plant Height cm 20 Fresh Plant at Maturity Large Medium ^ U U U * k * Small H h k.l Depth mean 73-1 ko.-j ^ T.U k 5.h k.l lia.5 1 Large seed was significantly different ( 01$) than small seed for all measurements. The mean of large and small seed was significantly ( 01$) different than medium seed. The effect of planting depth was linear for all measurements except for fresh weight which was quadratic ( 01$). Interactions between seed size and planting depth were significant for all measurements.

3 ALAM AND LOCASCIO: BROCCOLI-BEAN STUDIES 109 of planting on the rate of emergence, percent germination, height and fresh weight of plants in the greenhouse and plant weight at maturity in the field are given in Table 1. The main effect of seed size on germination was that large and medium seeds began earlier germination than from small seed. On the 8th day after seeding 37.5 percent emergence was recorded from large seed, 34.0 percent from the medium seed and 13.9 percent from the small seed. A significantly higher percent of seed germination was obtained with large seed as compared with small seed. Very little difference occurred between large and medium seed. germination increased linearly as the depth of planting decreased. Germination was reduced from 88.0 percent at the inch plant ing depth to 74.1 percent at the inch plant ing depth. An interaction between seed size and depth of planting indicated that the percent germination was greatly reduced with the in creased depth of planting in the small seed. With large and medium seed, germination per centages were little affected by planting depths from to inch depth. Both plant height and fresh weight samples of 20 day old plants (Table 1) were significantly greater from large seed than small seed. Plants from medium size seed were only slightly larger than from small seed. A significant linear reduction in plant height occurred as planting depth increased from to inches. The effect on plant weight, how ever, was quadratic. The largest reduction in weight occurred between the and inch depth with relatively less weight reduction with deeper plantings. Due to a significant interaction, plant height was reduced linearly as planting depth increased only with the large and medium seed. With the small seed, the plant height was reduced more sharply with planting depths over inches. Plant weights were reduced linearly for the me dium and small seed with increased planting depth. With the large seed, the greatest weight reduction occurred between the and inch depth with relatively less reduction with deeper plantings. Figure 1 ilustrates these effects of seed size and planting depth on 20 day old plants. i Flff^e i-tteffect8j t seed size and planting depth on the grrowth of 20 day old broccoli plants. sizes were large, M-medium, and S-small. Planting depths were %, 1, lms and 2 inches.

4 110 FLORIDA STATE HORTICULTURAL SOCIETY, 1965 Broccoli head formation was quite poor due to prevailing high temperatures. Yields of plants, taken as fresh weight, are shown in Table 1. Yields are significantly greater from large seed than small seed. Medium seed yielded inter mediately but slightly closer to the small seed. The effect of planting depth was a linear decrease in yield as the planting depth increased. An interaction between seed size and depth of planting significantly affected yield. Plant weight decreased linearly with increased plant ing depth only with the small seed. With the large and medium seed, the largest reduction in yield occurred between the and inch depth with relatively less reduction at the inch depth. Beans: Results of greenhouse and field ex periments with beans are given in Table 2. germination was about two to three days more rapid with the large seed than with the small seed. Planting depths from to inches also resulted in about a two to three day interval in germination. Germination of large seed planted inches deep was complete by the sixth day. Small seed planted inches required nine days to complete germination. Although the rate of germination was influenced by treat ments, neither seed size nor planting depth af fected the final perecnt germination. Plant heights and weights taken 35 and 55 days after seeding (Table 2) were significantly affected by both seed size and planting depth. The main effect of seed size was that both plant height and weight were significantly greater TABLE 2. Effect of seed size and depth of planting on rate of emergence, percent germination, plant height, fresh weight and yield of beans in greenhouse and field studiesl. C21EENH0USE STUDY FIELD Size Depth 6 fl Days after seeding 9 35 Plant Fresh 55 Plant Fresh Bean Yield Large Medium Small Inches B7. 5 U Germination Percent Height cm k Q.k k.h 3.3 k.l Height cm fc.l If 2k.k li U7-3 kh.l u lbs/plot k.6 k U.2 Depth' mean k.l k9.2 kl.k Large seed was significantly different ( 01$) than small seed for all measurements except in final germination. The mean of large and small seed was significantly different (05$) than for medium seed for fresh weight 55 days after seeding. A significant linear affect ( 01$) of planting depth was obtained for all measure ments except total germination. Interactions were significant "between seed size and planting depth on plant fresh weights 35 and 55 days after seeding.

5 ALAM AND LOCASCIO: BROCCOLI-BEAN STUDIES 111 from the large than the small seed. Medium seed produced plants ranging in size between those from the large and small seed. The main effect of planting depth was a linear reduction in plant height and weight as the planting depth in creased. Plants 35 days after seeding were 65 percent as tall at the inch depth as at the inch depth. Due to a significant interaction, plant fresh weights were relatively more reduced by deep planting of the small seed than the large seed. Effects of seed size and planting depth on the cotyledon leaf and the first trifoliate leaf 35 days after seeding are illustrated in Figure 2. Under field conditions, little difference in the time required for the different seed sizes to ger minate was noted. Depth of planting also had little effect on emergence rate. Yield of beans, shown in Table 2, was sig nificantly affected by both seed size and depth of Figure 2. Effects of seed size and planting: depth on the size of the cotyledon leaf and first trifoliate leaf of 35 day old bush beans. sizes were L-large, M-medium and S-small. Planting depths were yst 1, 1V2 and 2 inches. S planting. However, the effects of planting depth were slight. Yields were significantly greater with large seed than small seed. Yields from medium and small seed were 78 and 49 percent respectively of the yield from the large seed. Discussion Germination rates of both broccoli and beans were reduced as seed size decreased and plant ing depth increased. Only with broccoli was the final percent germination influenced by treat ment. Similar reductions in percent germination have been reported for forage crops with a de crease in seed size (9) and an increase in plant ing depth (1, 2, 4, 6). However, germination of small broccoli seed was more reduced by in creased planting depth than large or medium seed. Stickler and Wassom (15) reported a similar interaction of seed size and planting depth with birdsfoot trefoil. As reported here, germination of bush beans was not affected by seed size or planting depth. Germination of lima beans (17) have been reported to be little affected by seed size. Work by Rotunno (12) indicate that varieties of the same crop may respond differently. He found that in some varieties of radish, highest germination percentages occurred with large seed, in others the medium, and in still others, the small seed. size had significant effect on plant height and fresh weight. Larger and more vigorous seedlings were obtained in both the crops with large seed. Smaller seeds showed lower seedling vigor. Similar results have been reported (7, 13, 14, 17, 18). There was a linear reduction in plant height and weight with the increased depth of planting of both broccoli and bush beans. Plants from shallow depths were larger and more vigorous. Interaction of seed size and depth of planting on plant height and fresh weight was significant. Kalton et al. (6) and Erickson (4) also found that small seed resulted in more decreased vigor than large seeds with increased depth of plant ing. This suggests that the plant is entirely dependent for survival on the initial food stored for early growth until the plant starts producing its own food. The poor performance of small seeds at deep depth may be attributed to an exhaustion of reserve food supply as emergence is accomplished. In the field, heads formed in broccoli were

6 112 FLORIDA STATE HORTICULTURAL SOCIETY, 1965 few due to unfavorable environmental conditions; however, the fresh weight of plants indicates the superior value of large seed. Early yields may be obtained from large seed as pointed out by Tompkins (16). The effect of seed size on the yield of beans was that large seed produced significantly higher marketable beans than medium and small seed. Wester (18) found that plants of Fordhook 242 lima beans from large seed were more productive than smaller seeds. Only a slight but significant linear decrease in yield occurred as the seeding depth of beans was increased. It is evident from the field studies that seed ing depths used in this study has little effect on large seeded crops like beans but had marked in fluence on small seeded crops like broccoli. With both crops, however, seed size had significant affect on plant growth and yields. With small seeded crops planting depth is quite critical and should be controlled. size and planting depth influenced the initial rate of germination in both crops even though final germination was not affected in beans. This early difference of 3 to 6 days in germination from various seed sizes and depths often accounts for poor uniformity of growth and maturity. Results of this study are conclusive, and strongly indicate the superior value of large seeds and shallow depth of planting. Summaky Greenhouse and field studies were initiated to study the effects of seed size and depth of planting on broccoli and beans. Results indicate that with both crops the rate of germination in creased as the seed size increased but decreased as planting depth increased. Differences in ger mination time required for large seed planted shallow and small seed planted deep were about five days for broccoli and three days for beans. With broccoli the percent germination, plant height, and fresh weight in the greenhouse and fresh weight in the field increased as seed size increased and planting depth decreased. Due to an interaction, a larger reduction occurred with deeper planting of small seed than medium and large seed. With beans, seed size or planting depth had no effect on the percent germination, but the rate of emergence, plant growth and yield were in fluenced by treatment. Plant height, fresh weights and bean yields increased as seed size increased, and decreased as planting depth in creased. As with broccoli, growth and yield from small bean seeds were more reduced by deeper planting than from large and medium seed. LITERATURE CITED 1. Beveridge, J. L., and C. P. Wilsie Influence of depth of planting seed size, and variety on emergence to seedling vigor in alfalfa. Agron. Jour. 51: Black, J. N The influence of seed size and depth of sowing on pre-emergence and early vegetative growth of subterranean clover (Trifolium subterraneum). Jour. Agr. Res. 7: Cameron, J. W., A. Van Mam and D. A. Cole, Jr size in relation to plant growth and time of ear maturity of hybrid sweet corn in winter planting area. Proc. Amer. Soc. Hort. Sci. 80: Erickson, L. C, The effect of alfalfa seed size and depth of seeding upon the subsequent procurement of stand. Jour. Amer. Soc. Agron. 38: Hoffman, I. C, The relation of size of kernels in sweet corn to evenness of maturity. Jour. Agr. Res. 31: (11) Kalton, R. R., R. A. Delong and D. S. Mcleod Cultural factors in seedling vigor of smooth bromegrass and other forage species. Iowa State Jour. Sci. 34: Kiesselbach, T. A Relation of seed size to the yield of small grain crops. Jour. Amer. Soc. Agron. 16 (10) : McKenzie, R. E., D. H. Heinrichs and L. J. Ander son Maximum depth of seeding eight cultivated grasses. Scientific Agriculture 26: Miller, P. G., and L. H. Pammel A study on the germination and growth of Leguminosae, especially with references to small and large seed. Iowa Agr. Expt. Sta. Bui Murphy, R. P., and A. C. Amy The emerg ence of grass and legume seedlings planted at different depths in five soil types. Jour. Amer. Soc. Agron. 31: Rogler, G. A size and seedling vigor in crested wheat-grass. Agron. Jour. 46: Rotunno. N. A Effect of seed on plant pro duction with special reference to radish. Botanical Gazette. 78: Rudolfs, W Influence of temperature and initial weight of seeds upon the growth-rate of Phaseolus vulgar is seedlings. Jour. Agr. Res. 26: Schmidt, David The effect of the weight of the seed on the growth of the plant. N. J. Agr. Expt. Sta. Bui Stickler, F. C. and C. E. Wassom Emergence and seedling vigor of birdsfoot trefoil as affected by planting depth, seed size and variety. Agron. Jour. 55: Tompkins, Daniel Broccoli maturity and pro duction as influenced by seed size. Abst. Amer. Soc. Hort. Sci. 62nd Ann. Meeting, p Wester, R. E., and Roy Magruder Effect of size, condition, and production locality on germination and seedling vigor of Baby Fordhook bush lima bean seed. Proc. Amer. Soc. Hort. Sci. 36: Wester, R. E Effect of size of seed on plant growth and yield of Fordhook 242 bush lima bean. Proc. Amer. Soc. Hort. Sci. 84: