STUDIES IN F, AND F 2 OF CROSSES BETWEEN WINTER AND SUMMER TURNIP RAPE Rolf Manner Linköping, Sweden Received September 10, 1958 The seed yield of summer turnip rape has in many cases been small or in- sufficient, which seems to be largely due to the rather small specific yield of this turnip rape type. One of the reasons for the interest in and for the initiation of crosses between summer and winter forms of turnip rape was the hope of obtaining types giving higher yield. An other reason for the interest in these crosses was the possibility of developing leafy turnip rape types which could be used for green fodder production. Further, the author was interested to see the influence of different winter turnip rape varieties used as parents, on crosses with one common summer turnip rape. Material and methods The present investigation was carried out at the Plant Breeding Institute Gulläker, Hammenhög, Sweden. The study was undertaken in connection with the practical plant breeding work at the institute. The crosses were carried out by the author in 1951. The hybrid seeds and the seeds of parents were sown in planting-boxes in the early spring of 1952. The plants were planted in the field at the beginning of May. The planting was successful with the exception of the Mette plants, which had begun to shoot before planting and consequently had reached a developmental stage where the plants would not survive planting. In order to have some possibilities for comparison Mette was at the same time sown. These Mette plants were then used for comparisons with Fj of the crosses, and the winter turnip rape varieties used as parents in the crosses. The plants were planted at distances of 45 X 45 centimetres. The numbers of investigated plants are given in Table 1. The developmental stage and the plant height of the Fj plants were determined on August Ist. Seed yield per plant, seed weight per silique, length of silique and number of seeds per silique were investigated. 32 The F 2 plants of the investigated crosses were grown in the summer of 1953 and were partly compared with Mette and partly with the winter turnip rape varieties used as parents in the actual crosses. The plants were grown in sown stands. The x 2 tests were undertaken in conformity with Finney (2) and determined with the help of Fisher and Yates (3). The development of F 1 The developmental stage of the F v plants in comparison with parents on August Ist, 1952 is given in Table 1. At this date all the plants of the summer turnip rape variety Mette had reached the ripening stage. The varieties of winter turnip rape used as mothers did not shoot with the exception of two plants of Rapido. All hybrid plants were later than Mette and earlier in development than the corresponding mother. In some cases, however, plants were classed in the same group as Mette and the mother variety plants, respectively. The slowest rate of development was shown by the hybrids between Storrybs and Mette. In all four cases the height of the hybrids was on an average larger than that of Mette and the corresponding mother variety of winter turnip rape. The tallest hybrids on August Ist were on an average those of the cross Rapido X Mette, which were on an average twice as high as the father and mother varieties (Tabel 1). Of the whole number of plants about half of the hybrids Gruber X Mette and Sprengel X Mette gave seed yields, whereas about threefourths of the plants of Rapido X Mette gave seed yields. The smallest number of the hybrids giving rise to seed-bearing plants was found in Storrybs X Mette, which indicates that the smallest part of the plant number gave seed for the hybrids with the latest flowering Table 1. The development and height of F x in comparison with the parents. Develomental stage August Ist Plant height August Ist iS o . Variety or .4 s"&■■% S v gm-5 ' c S 1 "C ■§ 'S c C u cross 5 -5 -o ?: c c o---=so>ci a 3 c x *= | -5 £ E | J 55 |J f I I g | ac PQ Mette 30 30 45.0 Rapido x Mette.F, 120 1 53 21 19 4 22 94.4 36 140 Rapido 8 6 2 25.0 5 65 * Gruber x Mette, F, 98 G 43 14 15 8 12 70.7 2 ISO Gruber 4 4 ______ _ 16.3 10 30 Storrybs X Mette, F, 24 1 3 16 4 73.5 40 125 Storrybs 16 16 13.1 10 SO Sprengel X Mette, F, 103 8 3 56 23 8 3 2 66.7 2 115 Sprengel 8 8 __ - 40.0 40 40 33 Table 2. Plants giving seed yields 1932. Parents Mother Father Hybrids Rabido x Mette non all 93 out of 120 Gruber x Mette non all 42 » » 98 Storrybs x Mette non all 4 » » 24 Sprengel x Mette non all 49 » » 103 Table 3. Beginning of flowering and the plant height of the winter turnip varieties used in the crosses as parents. Variety Beginning of flowering Plant height days + Rapido cm + Rapido Rapido May 9th 80 Gruber +2 +5O Storrybs +4 +6O Sprengel +2 +2O and ripening parents and w ith the highest plants, whereas the Rapido-hybrids gave the largest number of seed-bearing plants, Rapido having been the earliest and lo- west of the mother varieties at maturity. This indicates a relationship between the characteristics of the parents (Table 3) and the characteristics of the hybrids (Table 2). A corresponding difference between different hybrids is also found in Table 1 as regards the developmental stage of the F, hybrids on August Ist, 1952. The differences between the different groups of hybrids in the number of Fj-plants giving seed yields (Table 2) are in most cases significant, namely; Rapido X Mette Sprengel X Mettex* = 22.14xxx , Gruber X Mette Storrybs X Mette z 2 = 4.87 x , Rapido X Mette —Gruber X Mette x 2 = 27.87 xxx , Rapido X Mette Storrybs X Mettez2 = 18.76xxx and Storrybs X Mette—Sprengel X Mette z 2 = 7.61 xx. The seed yield and seed-setting characters of F 1 of the crosses In all the investigated crosses the seed yield per plant was on an average considerably higher per seed-bearing plant than in Mette summer turnip rape. The same was applied to the seed weights per plant, if all the plants were taken into consi- deration.The only exception was F x of the cross Storrybs X Mette (Table 4). The highest seed weights per silique, the largest length of silique and the highest number of seeds per silique were found in F, of the cross Gruber X Mette. The smallest average seed weights and numbers of seeds per silique were found in F, of the cross Storrybs X Mette (Table 5), but these hybrids were very late in develop- ment. 34 Table 4. Seed yields in Fj of the crosses. Variety and Number of Milligrams Milligrams cross investigated of seeds of seeds per plant plants per investi- if all plants are included gated plant Mette 30 193 193 Rapido x Mette, F, 93 2327 1803 Gruber x Mette, F, 42 1118 509 Storrybs x Mette, F, 4 775 129 Sprengel x Mette, F, 49 1102 524 Table 5. Seed-setting characteristics in F, of the crosses. Variety Number of Seed weight Lenght of Number of and cross investigated milligrams silique in seeds per plants per silique millimetres siliipie Rapido x Mette, F, 75 17.3 37.9 13.7 Gruber x Mette, F! 35 26.7 48.8 15.7 Storrybs x Mette, F! 4 13.0 45.0 9.8 Sprengel x Mette, F, 44 15.3 43.7 13.0 Development of F 2 of the hybrids F 2 of the crosses began to flower 3—5 days later than Mette. The varieties of winter turnip rape used as mothers did not reach the flowering stage in the summer of 1953 in any sigle case. In comparison with the flowering of Mette that of the hybrids was much later and slower. Further, the flowering of the hybrids was much delayed through the large size of the plants and their leafiness. Owing to this the seed yield of the hybrids was uneven and not of the same high quality as that of Mette. The plant height of the hybrids was on an average smallest for Sprengel X Mette and largest for Storrybs X Mette, whereas the plant height of varieties used as mothers was the reverse according to the information given in Table 6, when sown the same spring. The seed yield and seed-setting characteristics of F 2 of the crosses The mean length of the siliques was about the same for Mette and the hybrids. The same is also largely valid for the number of seeds per silique, though a small tendency to higher mean numbers is to be found in the hybrids (Table 6). 35 Table 6. Development of characteristics inF 2ofthecrosses. Be Plant height Mean Largest Variety Num- gl ' g About Length of Number Seed weight Length of Number of Seed weight and cross ber jjav J u ug' silique, of seeds per silique, ' ee W6lg ' silique, seeds per per silique flower- ' Bth sth ~,. ... „. milligrams .... ->f)tli millimetres per silique milligrams ö millimetres silique milligrams Mette 8 8.6 40 54 56 37.8 13.4 30.1 2.25 46.3 20.0 47.5 Rapido x Mette 55 11.6 8 56 106 34.4 14.2 36.5 2.56 42 3 21.3 55.6 Rapido 5 22 Gruber X Mette 25 11.6 8 53 105 38.1 13.7 36.7 2.67 47.2 20.5 59.9 Gruber 5 58 Storrybs x Mette 2 13.6 5 38 108 36.1 13.6 44.0 3.25 46.1 17.5 55.0 Storrybs 6 12 Sprengel X Mette 22 12.6 8 51 98 38.3 14.6 39.6 2.71 46.9 19.9 58.2 Sprengel 5 80 36 All the mean values as well as all the largest values as to seed weight per silique were considerably larger than the corresponding values in Mette. The higher seed weight per silique was in the main due to higher mean seed weights. The difference was in all cases larger than ten per cent, which must be considered exceptionally large (Table 6). Dicussion Earlier investigators (cf. Baur, 1) have stated that the hybrids are fertile. This has in the main been confirmed in the present investigation. It was very interesting to observe the difference in the developmental rhythm between hybrids with the same summer turnip rape, Mette, as father, and different winter turnip rape varieties as mother. These differences were especially pronounced as regards the percentage of plants giving seed yields. The differences in the seed yields the seed-setting characteristics were in some cases very small. The very large differences in the seed yields between Mette and the hybrids in Fj (Table 4) are largely due to the considerable distance between the plants and to the ensuing very large vegetative development of the hybrid plants, whereas Mette had a clearly limited vegetative development. Judging by the results of the present study the hybrids seem to be correspon- dingly larger and slower in development the larger and slower the winter turnip rape used in the cross. Summary In the present study four hybrids between winter and summer turnip rape are compared with each other and with their parents. In all crosses the father was the same summer turnip rape, namely Mette. Fj and F 2 of the hybrids were intermediate as regards their development in comparison with the parents. About three-fourths of the F t plants of the cross Rapido X Mette, one half of Fj of the crosses Gruber X Mette and Sprengel X Mette, and only a small part of the crosses Storrybs X Mette gave seed yields. The seed yield per plant of the F,-hybrids was larger than that of the summer turnip rape Mette. The seed weight per silique and the mean seed weight were considerably higher in F 2 of all the hybrids than in the summer turnip rape Mette. The green fodder production of the hybrids can be expected to be large. The hybrids seem to be usable in plant breeding work. REFERENCES (1) Baur, G. 1944: Der Riibsen. - Handbuch der Pflanzenziichtung. IV, Band, 238—242. Berlin (2) Finney, D. J. 1933: An introduction to statistical science in agriculture. 179 pp. Copenhagen’ (3) Fisher, R, A. and Yates, F. 1953: Statistical tables for biological, agricultural and medical research’ 126 pp. Edinburgh. 37 SELOSTUS: SYYS- JA KEVÄTRYPSIN VÄLISTÄ RISTEYTYSPOPULAATIOITA KOSKEVIA TUTKIMUKSIA Rolf Manner Linköping, Ruotsi Tutkimuksessa todetaan, että keväällä kylvetyt Fx- ja F2 -sukupolvet kasvavat ensimmäisenävuonna vanhempiaan paljon korkeammiksi. Näin ollen on syytä tutkia lähemmin risteytyspopulaatioiden arvoa vihantarehukasvina. Kehitysnopeudeltaan F - ja F 2-sukupolvet ovat vanhempiensa välimuotoja. Risteytyssekakasvustojen siemensato yksilöä ja litua kohti oli suurempi kuin kevätrypsillä. Mette oli kaikissa risteytyskombinaatioissa hedekasvina. Emikasvina on käytetty Rapidoa Gruberiä, Sprengeliä ja Suurrypsiä (Storrybs). Emikasvikannasta riippuen oli eri risteytyspopulaatioi- den kehitysnopeudessa todettavissa selviä eroja. Tämä merkitsee sitä että syys- ja kevätrypsiä ristey- tettäessä on syytä valita vanhemmat huolellisesti, koska mm. risteyssekakasvustojen kehitysnopeus näyttää olevan positiivisessa vuorosuhteessa risteytysvanhempien kehitysnopeuteen.