Breeding of Fruit and Plantation Crops

Mutation breeding scheme for the improvement of horticultural tree plants

	1st year	Generation	Activity
A.	Initial explant	Shoot meristem (cutting, scion, rooted scion, etc)	Mutagen application x-rays (stabilipan 220V, 15 mA), or gamma rays (90 Co), Chronic or acute to establish the suitable treatment dose, grafting, rooting etc.
B.	Occurrence of a chimeric situation (mericlinal, sectroial) in auxillary bud meristems.	Shoot growth (M1V1 generation)	Cutting back of the M1V1 shoot at the fourth basal node. Vegetative propagation of M1V1 buds (either from the basal or the median zone)
2nd Year
C.	Occurrence of possible uniform periclinal parts (scion, branch, tree)	Shoot growth (M1V2)	Isolation of induced somatic mutation, vegetative propagation of the mutated M1V2 shoots. Cutting back of the unmutated M1V2 shoots at the fifth basal node
3rd Year
D.	Genetic uniformity achieved within the plants of a mutated clone	Mutant growth (M1V2)	Further isolation of somatic mutations and preliminary evaluation of the mutants. Vegetative propagation of the mutated M1V3 shoots, normal pruning of the fruit trees.
4th – 9th year
E.	Verification of the genetic stability of the mutant and the sexual transmission of induced somatic mutations	Vegetative growth and fruit bearing phases of the mutants	Evaluation of mutant’s performance, vegetative propagation of the mutants for agronomic traits. Crossing of the mutant, if possible, with other variety, followed by segregation.
10th year
F.	Final assessment	M1 V10 generation of the mutants	Release of improved clones Registration and patenting of new variety, Plant production in a nursery and certification.