A study of some aspects of the taxonomy, cytology, genetics and physiology of the tropical legume Indigofera spicata Forsk, and allied species

Guerassimoff, Julius. (1965). A study of some aspects of the taxonomy, cytology, genetics and physiology of the tropical legume Indigofera spicata Forsk, and allied species Master's Thesis, School of Land, Crop and Food Sciences, The University of Queensland.

       
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Author Guerassimoff, Julius.
Thesis Title A study of some aspects of the taxonomy, cytology, genetics and physiology of the tropical legume Indigofera spicata Forsk, and allied species
School, Centre or Institute School of Land, Crop and Food Sciences
Institution The University of Queensland
Publication date 1965
Thesis type Master's Thesis
Supervisor Dr. E. M. Hutton
Total pages 95
Language eng
Subjects 0703 Crop and Pasture Production
Formatted abstract The genus Indigofera has a wide distribution throughout tropical and subtropical regions of the world and also extends into regions with a more temperate Mediterranean climate. All species known have a basic chromosome number of eight (8), and diploid, tetraploid and hexaploid types are found. Only diploids and tetraploids were encountered in this work.

Varying degrees of toxicity have been reported for different Indigofera species and Indigofera spicata Forsk., the species dealt with in this study, is highly toxic, preventing its successful use as a pasture plant. A number of lines of I. spicata and some related species were introduced from various world sources by the C.S.I.R.O.
Cunningham Laboratory, Brisbane, Australia. The main purpose was to find genetic material which showed promise of eliminating the toxic principle from I. spicata by application of various breeding techniques. Chromosome counts were made on all these introductions as well as observations on their growth habit and flowering behaviour.

Using special techniques involving the raising of the relative humidity around the emasculated and pollinated flowers, hybrids were obtained from four I. spicata introductions. In the F2 and F3 populations of the crosses 16O69* x 18557 and 16110 x 18557 (18557 used as male parent in both hybrids), observations were made on the inheritance of eight different characters. These included:- stem thickness, stem colour, leaf shape, plant density, amount of adventitious rooting on lateral stems, perenniality, flowering, and podsetting. A certain amount of sterility was encountered in the populations and this was investigated also. The more promising agronomic types in the F3 population were compared with the parents in an F4 yield trial.

I. spicata seed was given different dosages of Co60 gamma irradiation, to determine the critical dose and with the hope of producing mutant plants free of the toxic principle. Time did not permit the evaluation of the population. The effects of irradiation dosage on pollen fertility were studied on the highest dosages used, viz. 100 Krads, 110 and 120 Krads.

A diploid (2n = 16) type (C.P.I.24205) closely resembling I. spicata and proving to be non-toxic has shown promise as a pasture species at the C.S.I.R.O. Pasture Research Station, Samford, Queensland. Using colchicine an autotetraploid was induced from this diploid type. It was thought that non-toxic I. spicata strains could be bred by crossing this induced autotetraploid with the best F4 selections from
the hybrids made previously. Chromosome doubling produced interesting changes in plant morphology- A comparison was made between the raw autotetraploids and their diploid progenitors, the differences in certain characters being measured.

All lines of I. spicata and selected F4, hybrids from them as well as the diploid line O.P.I. 24205 were found to have a day neutral response for flowering. The photoperiodic requirements were studied in a controlled environment chamber under two day lengths and six different day and night temperature combinations. The growth of plants under the different treatments was also observed.
Keyword Indigofera spicata

 
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