The laxatum (lax) genes reduce spike internode density (= s.i.d.). To date 79 induced mutants have been localized by diallelic crosses to 26 loci.

Mutants with two figure indices are in Bonus barley (s.i.d. 34.4mm) and with higher indices in Foma barley (s.i.d. 32.5mm). Loci from d to o and froin df to nf are preliminary. This means that the first series is allelism tested within the Bonus material only and not yet to the loci df to nf of the second series comprising Foma-lines. The second series has similarly been tested for allelism only within Foma material.

Lax spikes are also found as pleiotropic effects in other mutant traits affecting the inflorescence such as branching compositum (com), accordian basal rachis internodes (abr) and some short awned breviaristatum (ari) mutants.

Locus lax-a: s.i.d. 34-40mm, florets with five anthers, thin grain with visible aleurone, awns with a broad base.

lax-a⁰¹, -a⁴, -a⁸, -a²⁰, -a³⁷, -a³⁹, -a⁵⁹, -a²⁰⁸, -a²¹⁸, -a²²², -a²²⁹, -a²⁴⁹, -a²⁵⁶, -a²⁷⁸, -a²⁸⁶.

Locus lax-b: s.i.d. 43.1mm, shrunken endosperm. with xenia, long spikes.

lax-b¹.

Locus lax-c: s.i.d. 36.1-37.5mm, angular, semi-naked grain with Visible aleurone (Tike in lax-a).

lax-c²¹, -c²³.

Locus lax-d: s.i.d. 33.9-36.5mm, early heading plants with normal to vigorous growth.

lax-d², -d²⁷, -d⁸³.

Locus lax-e: s.i.d. 39.5-41.6mm, plants with broad leaves.

lax-e⁶, -e¹⁶.

Locus lax-f: s.i.d. 35.8-39.1mm, spikes sometimes top-sterile, plants mostly vegetatively normal.

lax-f⁷, -f⁶¹.

Locus lax-g: s.i.d. 36.1-37.1mm, some sterile florets, few tillers per plant.

lax-g²⁵, -g⁵⁹.

Locus lax-h: s.i.d. 36.6-41.2 mm, some sterile florets, platns with dark-green leaves.

lax-h²⁶, -h³⁸

Locus lax-i: s.i.d. 36.9-40.7 mm, thin grain, plants with dark-green leaves.

lax-i²⁸, -i⁵⁰.

Locus lax-j: s.i.d. 30.6-42.5mm, some sterile florets.

lax-j²⁹, -j³³, -j⁴⁹.

Locus lax-k: s.i.d. 34.2-36.4mm, plants with narrow dark-green leaves.

lax-k⁴², -k⁴⁴, -k⁸⁴.

Locus lax-l: s.i.d. 36.0-42.2mm, spikes top-sterile.

lax-l⁶⁰, -l⁷⁸.

Locus lax-m: s.i.d. 36.7-39.9mm, some sterile florets, plants with broad, light-green leaves.

lax-m⁶⁵, -m⁸⁰.

Locus lax-n: s.i.d. 32.3-32.8mm, curly awns, plants with narrow leaves.

lax-n⁶⁷, -n⁶⁸.

Locus lax-o: s.i.d. 37.3-39.0mm, irregular spikes, relatively early mature.

lax-o⁷⁹, -o⁸⁸.

Locus lax-df: s.i.d. 32.8-33.Omm, relatively early maturing, plants with dark-green leaves and vigorous growth.

lax-df²⁴⁰, -df²⁴¹.

Locus lax-ef: s.i.d. 31.7-41.8mm, mostly long spikes and broad leaves.

lax-ef²⁰⁵, -ef²²⁵, -ef²³⁶, -ef²³⁷, -ef²³⁸, -ef²⁶³, -ef²⁸⁷, -ef²⁹⁰, -ef²⁹², -ef³⁰⁹.

Locus lax-ff: 3.i.d. 31.3-32.3mm, some sterile florets, round grain.

lax-ff²¹⁶, -ff²³³.

Locus lax-gf: s.i.d. 33.2-39.5mm, some sterile florets, relatively early maturing, plants with dark-green leaves.

lax-gf²¹⁷, -gf²⁸⁸.

Locus lax-hf: s.i.d. 38.4-40.6mm, long, slender to fusiform grain, plants with narrow -dark-green leaves.

lax-hf²³², -hf²⁴², -hf²⁴⁴, -hf²⁵¹.

Locus lax-if: s.i.d. 32.3mm, probably translocations in both mutants, plants Mostly vegetatively normal.

lax-if²⁴⁶, -if²⁴⁸.

Locus lax-jf: s.i.d. 35.2-36.9mm, relatively early maturing, plants mostly with dark-green leaves.

lax-jf²⁵³, -jf²⁵⁴, -jf²⁵⁵.

Locus lax-kf: s.i.d. 32.2-32.8mm, plants mostly vegetatively normal.

lax-kf²⁶⁸, -kf²⁹⁵.

Locus lax-lf: s.i.d. 34.1-37.8mm, plants mostly vegetatively normal.

lax-lf²⁷³, -lf²⁷⁴.

Locus lax-mf: 3.i.d. 31.5-37.3mm, dry grain yellowish, plants mostly with dark-green leaves.

lax-mf³⁰⁰, -mf³⁰¹, -mf³⁰².

Locus lax-nf: s.i.d. 41.9-43.4mm, thin grain, spikes sometimes top-sterile.

lax-nf³²², -nf³²³.

REFERENCES, DESCRIPTIONS AND INDUCTION DATA:

Larsson, H.E.B. 1985. Morphological analysis of laxatum barley mutants. Hereditas 103, 239-253.

Larsson, H.E.B. 1985. Genetic analysis of laxatum barley mutants. Hereditas 103, 255-267.

Larsson, H.E.B. 1985. Linkage studies with genetic markers and some laxatum barley mutants. Hereditas 103, 269-279.

Larsson, H.E.B. 1986. Morphological and genetic analysis of laxatum mutants in barley. Acta Univ. Ups., Comprehensive Summaries of Uppsala Dissertations from the Faculty of ~cience 22. 32 pp. Uppsala, Sweden.

Larsson, H.E.B. and Lundqvist, U. 1986. Description of genetic stocks. BGN: 16, section VII.

Persson, G. and Hagberg, A. 1969. Induced variation in a quantitative character in barley. Morphology and cytogenetics of erectoides mutants. Hereditas 61:115-178.