THE INFLUENCE OF SEED SIZE ON EMERGENCE OF SEEDLINGS AND PLANT DEVELOPMENT IN GRAIN CROPS WITH SPECIAL REFERENCE TO SEEDING DEPTH Rolf Manner Agricultural Research Centre, Department of Plant Breeding, Jokioinen Received March 29, 1963 The dependence of grain yields on the size of the sown seed has been studied in a number of trials by earlier investigators. Very little or no influence of seed size has been observed in the experiments (3, 4). Shallow seeding depth (2.5 cm) was best for winter wheat if the soil contained enough moisture in the experiments of Stephans, Wanser and Bracken (5). The relative grain yield was 8 % smaller with 6.2 cm and 18 % smaller with 10.0 cm seeding depth than with 2.5 cm seeding depth. Nielsen and Overgaard (4) obtained in field trials greater grain yields from oats sown at 5 cm than at 10 cm seeding depth. Table 1. The quality of sown seed Kind of cereal Variety Year Small seeds Large seeds 1000-seed Germina- 1000-seed Germina- weight, g tion % weight, g tion % Winter rye Kungs II 1960 20.2 82 33.6 91 1961 20.8 95 33.3 95 1962 20.7 96 33,1 92 Winter wheat Odin 1960 25.5 92 49.5 95 1961 26.2 93 49.6 96 1962 26.0 86 49.2 89 Spring barley Rika 1961 22.0 90 50.9 96 1962 I 26.0 83 56.0 83 1962 II 25.9 82 55.7 81 Spring wheat Drott 1961 20.1 85 47.1 85 Ring 1962 I 26.0 90 50.0 93 Ring 1962 II 25.9 76 49.8 79 Oats Sol II 1961 16.6 93 38.6 95 1962 I 15.4 85 27.5 86 1962 II 15.3 90 27.2 90 139 Material and methods Data on the seed batches used in the study are compiled in Table 1. In each pair of small seeds and large seeds both seed batches were obtained from the same cultivation lot by grading. All seed batches were treated with mercury seed dressing preparation Betoxin. After preliminary cleaning, the seed was graded to effect a division of each seed lot into three parts: (1) about 10 %, small seeds; (2) about 80 %, »medium large» seeds; and (3) about 10 %, large seeds. Differences in germination per- centage between the small and large seeds could not be avoided. These differences were compensated so that the experimental results for small and large seeds became mutually comparable. The experiments were conducted in a greenhouse. The water supply and other environmental factors were the same in all tests of different seeding depths, seed sizes and species. The experiments were conducted in wooden pots 0.16 m 2 in size and with 20 cm soil depth. 192 germinating seeds were placed in each pot. Loam soil was used. The number of replications was three. The plants were counted 40 days after sowing. The seeding depths were 1 cm, 6 cm and 11 cm. The t-values were calculated as presented by Fisher (1) and the significance levels determined according to Fisher and Yates (2) denoting them by asterisks as follows: *** = P 5 0.001, *’|i ;P> 0.01, but > 0.001, and * = P <: 0.05, but > 0.01. Percentage of emerging seedlings Rye. In all comparisons, the large seeds gave a higher percentage of seedlings and plants than the small seeds used in the test (Table 2). The difference, in per cent of seedlings that emerged from small and large seeds was greater with greater seeding depth than with shallow seeding depth (Fig. 1). Table 2. Emergence of seedlings in per cent, 1960—62 Seed size and seeding depth Per cent seedlings emerged All crops in total Winter rye Winter Spring Spring Oats Difference t value wheat barley wheat between for the small and differ- large seeds ence Small seeds 1 cm 77.6 81.8 82.7 55.8 78.1 - - 6 cm 43.6 63.7 69.8 44.6 73.2 - 11 cm 4.0 28.1 34.9 19.4 42.0 - - Large seeds Icm 84.0 84.7 84.7 63.7 83.8 + 5.0 6.11*»* 6cm 57.4 69.0 77.7 53.2 80.6 + 8.6 4.43*** 11cm 17.1 41,2 45.6 32.5 56.8 +13.0 7.B2*** t value for the difference be- tween small and large seeds 4.62** 3.90** 1.93 5.69*** 4.56** + 8.9 B.BB*** 140 Winter wheat. A higher percentage of seedlings was obtained with large seeds than with small ones (Table 2). The tendencies were consistent with those observed in winter rye, but the influence of seed size and seeding depth seems to have been less with winter wheat. Spring barley. The percentage of emerging seedlings was higher for large seeds than for small seeds. It was higher in all individual experiments at 11 cm seeding Fig. 1. The relative emergence of seedling from small seeds in comparison with the emergence from large seeds (= 100.0). 141 depth for large seeds than for small seeds (Table 2). The influence of seed size and seeding depth seems to have been less in spring barley than in winter rye. Spring wheat. In all comparisons, seedlings were obtained in smaller numbers with small seeds than with large seeds (Table 2). Greater seeding depth produced a lower percentage of emerging seedlings in all experiments. The greater the seeding depth, the bigger the difference established in the number of seedlings emerging from small and from large seeds. Oats. Large seeds produced greater numbers of emerging seedlings than small seeds in all experiments (Table 2). Formation of shoots The number of shoots developed from 100 seeds was in every experiment smaller with small seeds than with large seeds (Fig. 1). The greatest difference in this respect between small and large seeds was observed in barley. Summary The influence of seed size on emergence of seedlings and plant development was studied in a number of trials with special reference to seeding depth. The results of the study lead to the following conclusions: The number of emerging seedlings and the number of developing shoots per 100 sown germinative seeds were smaller with small seeds than with large seeds. 3 Fig. 2. The number of shoots developed from 100 germinative seeds sown at different depths. 142 The influence of seeding depth on the percentage of emerging seedlings was more marked with small seeds than with large seeds. Differences were found between different crops. The strongest dependence of the observed quantities on seed size was displayed by winter rye at a great seeding depth. The differences between the studied crops could not be explained on the basis of differences in 1000-seed weights. Acknovvledgements. My best thanks are due to my former employer, The Swedish Seed Association, for the permission to carry out this investigation, to the Seed Growers’ Association of Östergötland for the permission to use their greenhouse, and to the Längman Cultural Foundation for financial support. REFERENCES (1) Fisher, R. A. 1950. Statistical methods for research workers. 354 pp. Edinburgh. (2) Fisher, R. A. & Yates, F. 1953. Statistical tables for biological, agricultural and medical research. 126 pp. Edinburgh. (3) Iversen, K. & Lindhard, E. 1903. Fortsatte Forsog med storre og mindre Saakorn af Toradet Byg, Seksradet Byg og Havre 1882 1900. Tidsskr. Planteavl 20:697 730. (4) Nielsen, N. J. & Overgaard, P. O. 1926. Sorterings-, Saamaengde og Saadybdeforsog med Havre paa Sandjord. Ibid. 32: 739 761. (5) Stephans, D. E. & Wanser, H. M. & Brachen, A. F. 1932. Experiments in wheat production on the dry lands of Oregon, Washington, and Utah. U.S. Dept. Agr. Tech. Bull. 329: 1-68. SELOSTUS; KORSIVILJOJEN ORASTUMISEN JA TAIMIEN KEHITYKSEN RIIPPUVUUS KYLVÖSIE- MENEN KOOSTA Rolf Manner Kasvinjalostuslaitos, Maatalouden tutkimuskeskus, Jokioinen Vuosina 1959—1962 suoritti tekijä sarjan vertailevia tutkimuksia siitä, miten korsiviljan oras- tuminen ja taimien kehitys riippuu kylvösiemenen koosta. Tutkimuksen kohteena olivat syysruis, syysvehnä, ohra, kevätvehnä jakaura. Tutkimuksen tarkoituksena oli selvittää, onko pienien ja suurien kylvösiemenien arvossa todettavissa eroja. Tutkimuksessa vertailtiin kahta eri siemenkokoa sekä kolmea eri kylvösyvyyttä. Pieni- ja suurikokoisen siemenen arvossa todettiin eroja. Pienien jyvien orastumisprosentti oli alhaisempi kuin suurien jyvien. Tämän lisäksi oli pienistä jyvistä kehittyneiden taimien versojen luku- määrä 100 kylvettyä itävää jyvää kohti alhaisempi. Pienistä jyvistä kehittyneiden taimien orastuminen oli enemmän kuin suurista jyvistä kehitty- neiden tainten riippuvainen kylvösyvyydestä. Viljelykasvien välillä voitiin osoittaa olevan eroavuuksia sekä orastumisprosenttiin että taimien versoutumiseen nähden. Syysrukiissa on todettu suurin ero pieni- ja suurikokoisen kylvösiemenen orastumisprosenttien välillä. Syysruis osoittautui tutkituista viljakasveista myös eniten riippuvaiseksi kylvösyvyydestä. Tutkittujen viljelykasvien välillä todetut eroavuudet eivät ole selitettävissä tuhannen jyvän painon perusteella.