Phene Analysis, Overdominance, Variability
Total Page:16
File Type:pdf, Size:1020Kb
Hereditas 86: 251-266 (1977) Effects of the Pallas gene in barley: phene analysis, overdominance, variability AKE GUSTAFSSON, GUNNAR EKMAN AND INGEGERD DORMLING Institute of Genetics, University of Lund Semka AB, Sundbyberg The Phytotron, Swedish University of Agriculture, Stockholm, Sweden GUSTAFSSON,A., EKMAN,G. and DORMLING,I. 1977. Effects of the Pallas gene in barley: phene analysis, overdominance, variability. - Hereditas 86: 251 -266 Lund, Sweden. JSSN 001 8-0661. Received May 1, 1977 Pallas barley is a high-yielding mutant induced by X-rays in Bonus barley and was among the first cereal mutants released into practice. It is characterized by a high lodging resistance and surpassed its parent variety Bonus, under good soil conditions, in yielding capacity. It has been widely cultivated in several European countries. It wasconsidered worth while to analyse the phene reactions of the mutant, its parent strain Bonus and their F,-hybrid (Pallas x Bonus) in the Stockholm phytotron under varied climatic conditions. Three photoperiods and two thermoperiods were chosen for study. Fifteen phenotypic traits (phenes) were analysed concerning generative and vegetative production, occur- rence and expression of dominance and overdominance, as well as phene variability (flexibility). Overdominance was common and often highly significant. Variability of individual phenes changed widely. In generative traits Pallas was more variable than Bonus and the F,-hybrid. Under certain climatic conditions, the hybrid, in its turn, was definitely less variable than the parents. An evident interaction of genotype and climatic condition on productivity and variability was found. Ake Gustafsson, Institute of Genetics, S-223 62 Lund, Sweden The barley mutant erectoides 32 (ert-k3’)was isolated In the year 1974, cross materials of Pallas x Pallas, in 1947 from Svalov’s Bonus barley. It became the Pallas x Bonus, F,, and Bonus x Bonus were pro- first wide-spread mutant variety in cereal species after duced by ordinary hybridization methods in the field. its official approval in 1958. Its high yielding potential In the following, the three materials are registered was established by Swedish, Danish, British and Irish respectively as PP, PB and BB. Pallas was chosen as results of cultivation (literature and discussions by the female hybrid parent in order to exclude a conta- GUSTAFSSON1963a and b, as well as by BORC et al. mination with selfed offspring in the F, materials. 1958, BORG 1959). A strict relationship between its Pallas is morphologically deviating from Bonus by its yielding ability and lodging resistance was shown to short and dense erectoides spikes (Fig. 1). The occur in official Danish trials (GUSTAFSSONand EK- mutant factor is most likely on the gene level. No MAN 1967). In the last decade, the mutant has gained sterility of genetic nature is found in hybridization. a new market in Spain, where it, as also its hybrid The mutant behaves in ordinary field experimentation descendant Hellas barley from Svalov, has covered as a recessive and segregates in a regular fashion. wide areas. Its parent variety Bonus, at a time both wide- spread and high-yielding, was originally produced by NILSSON-EHLE(see FROIER1954). The two genotypes, Material and methods mutant and parent, together with their F,-mono- hybrid offer suitable materials for studies on growth Three genotypes were tested in parallel phytotron and productivity in the Stockholm phytotron under experimentation: varied climatic conditions. Also features of domi- 1. Pallas x Pallas (PP) nance, overdominance and phenotypic variability 2. Pallas x Bonus (PB) could be included in the analysis of the data obtained. 3. Bonus x Bonus (BB) 252 A. GUSTAFSSON ET AL. Herediras 86 (1977) Fig. 1. To the left: four spikes of Bonus barley, to the right: four spikes of Pallas barley (erectoides 32). Among previously tried phytotron conditions, cf. GUSTAFSSONet al. 1975). Each genotype was three photoperiods were selected, known to give represented by maximally 10 individuals and distri- reproducible and rather normal growth effects (GUS- buted over the two trucks counted as separate units TAFSSON et al. 1974, 1975; DORMLINCet al. 1979, viz. in randomization. No root competition occurred. 1. 24 hours of light; with ca 22 000 lux at seedling level Border effects of plant position were not found. 2. 20 7, 9, ,, Fifteen variables (traits, phenes) were registered: 3. 16 ,, ,, ,, Two temperature conditions were applied. In Generative traits previous experiments they gave a rather low pheno- 1. Spike fertility, % typic variation with regard to seed setting and spike 2. 1000-kernel weight, g fertility 3. Kernel weight/plant, g 1. 20-10°C (20" for 16 hours, 10" for 8 hours) 4. Dry weight of spikes/plant (air-dried), g 2. 15-10°C (15" for 16 hours, 10" for 8 hours) 5. Number of kernels/plant The experiments were arranged in the form of a semi-randomized distribution of the three geno- Semi-generative traits types. Two trucks were used for a genotype compari- 6. Number of spikelets of first spike son, covering 2 x 14 pots, each truck being 0.25 mz in 7. Length of first spike, mm area. The plants were numbered from 1-28 (Fig. 2, 8. Number of heading tillers/plant Herediras 86 (1973 EFFECTS OF THE PALLAS GENE IN BARLEY 253 Fig. 2. 28 semi-randomized positions of three genotypes (PP, PB and BB) in six different photoperiod- thermoperiod arrangements. Vegetative traits The traits measured are of the quantitative type. 9. Length of first culm to flag-leaf, mm Here, it may be pointed out that the pleiotropic 10. Length of first culm to spike base, mm differences, caused by the homozygous Pallas gene, 11. Number of shoots/plant are rather striking in field cultivation. In spite of the 12. Dry weight of straw (vegetative matter) quantitative changes involved, the mutant is of the per plant, g “macro”, not of the “micro”, type, as further indi- cated below. Traits of earliness The analysis of variance gives high significances for 13. Time from sowing to flag-leaf formation, days numerous individual traits: 14. Time from sowing to heading, days (1) with regard to genotype response in traits 2, (3), (15.Time to maturity, days) 4,(6),7,9,(10),(13),(14),i.e.especiallyin 1000-kernel weight, dry weight of spikes, spike length, culm length Thus, the materials analysed cover: 3 genotypes, to flag-leaf, 3 photoperiods, 2 thermoperiods, 15 variables at the (2) with regard tophotoperiodresponse in traits 1,2,6, end stage, with 56 PP, 58 PB and 54 BB individuals, 7, 9, 12, 13, 14, i.e. especially in spike fertility, 1000- which means 2520 measurements in all. Additional kernel weight, number of spikelets, spike length, culm measurements were continually carried out every 14th length to flag-leaf, dry weight of straw, earliness, day during the growth period. (3) with regard to thermoperiod response in traits 1,6, (7), 9, 13, (14), i.e. especially in spike fertility, number of spikelets, culm length to flag-leaf, earliness (time of 1. General processing of data: genotype, photoperiod, ’ flag-leaf formation), thermoperiod effects (4) with regard to interaction of genotype and photo- Trait 15, plant maturity, was excluded from the dis- periodin traits 2 and 11, i.e. in 1000-kernel weight and cussion owing to the difficult evaluation of the indi- number of shoots, vidual mixed genotypes. Traits 13 and 14 (time to (5) with regard to interaction of genotype and thermo- flag-leaf formation and heading) can be analysed with period in traits 2, 11 and 12, i.e. 1000-kernel weight, full accuracy, however. The number of measurements number of shoots and dry weight of straw, and used amounts to 2352. (6) with regard to interaction of photo- and thermo- Each plant and trait is considered one observation. period in all traits except for traits 7 and 9 (spike The data as processed in Table 1 suffice for a detailed length and culm length to flag-leaf). These two traits phenogenetic analysis. A noteworthy result is the high involve the two “macro” differences between Pallas degree of accuracy indicated for most conditions and and Bonus. traits, in spite of the low number of individuals of The high accuracy of phytotron cultivation, also in each genotype and condition (9-10 individuals). quantitative traits with small differences, is evidenced 254 A. GUSTAFSSON ET AL. Hereditas 86 (1977) Table 1. Processing of genotype, photo- and thermoperiod influences on 14 variables in phytotron cultivation of mutant barley (Bonus x Bonus, Pallas x Bonus, Pallas x Pallas) Variable I 2 3 Geno- Photo- Inter- Geno- Thermo- Inter- Photo- Thermo- Inter- type period action type period action period period action 1. Fertility - *** - - I** - *I* *** *** 2. 1000-grain weight *** *** ** *** - *** *** I** *** 3. Kernel weight * * - *** *** - - ~- *** 4. Spike weight ** - - *** *** - - ._ *** 5. No. of kernels - *** - - *** __ - ~- I** 6. No. of spikelets *** *** - * *** - *** I** *** 7. Spike length *** *** - *** *** - *** * __ 8. No. of heading tillers - *** - - __ __ - ~~ *** 9. Culm length flagleaf ** *** - ** ** - *** *** - 10. Culm length spike base * * - *** *** - - ~- *** __ - - .- 11. No. of shoots - *** *** *** *** 12. Dry weight straw - *** - - - *** I** I** *** 13. Flag-leaf formation *** *** - * ** - *** *** *** 14. Time of heading *** I** __ - * __ *** *** *I* by this set of experiments. Of 126 individual differen- 3. Generative traits (1-5 in Table 1) ces no less than 59 lie below P-values of 0.001 and 14 -spikefertility (Table2). -As evidenced by more lie below 0.05, with either** or*. Table 1 both Dhoto- and thermoDeriod exert a -areat influence on the fertility in the conditions applied. All three genotypes are less fertile at the high temperature (20-10°C) than at the low one (15- 2. Detail analysis of individual traits loo). Pallas values at 15-10" are lower than those of A complete analysis of the 14 traits is not included in Bonus.