Rabindra Krishna Basu

Investigations on a new Beta (Chenopodiaceae)

Both the common sugar beet and Indian spinach (locally called Palong) have so far been considered to be the same species, Beta vulgaris L. Critical morphological, karyological, and biochemical studies revealed that Indian spinach is strikingly different from B. vulgaris and is described here as Beta palonga Basu & Mukherjee sp. nov.

Induction of high-yielding mutants in jute

Abstract Repeated selection of tall and thick-stemmed plants made in a number of generations after treatment with X-rays and 32 P on jute seeds led to the isolation of 4 high-fibre-yielding mutants, 2 each in Corchorus olitorius and C. capsularis . The capsularis mutants had an unusual combination of characters of early-flowering and short-flowering period. Evidence is presented to indicate that high-fibre yield of an X-ray mutant, Tall Mutant , over the mother line R. 26 in C. olitorius is mainly due to increased number of ultimate fibre cells.

THE INDUCTION OF EARLY FLOWERING MUTANTS IN CORCHORUS OLITORIUS L

Abstract From the X-irradiated and P 32 treated populations of two varieties of Corchorus olitorius , mutants were isolated which on average flowered earlier than the control and had greater plant to plant variation. The earliness of 79 days in a X-ray induced mutation and of 81 days in a P 32 induced mutation in mean time of flowering over their respective controls are remarkable. The early mutants had long flowering periods. Evidence has been presented to show that earliness was associated with reduction in node number at first flowering. Four early mutants were superior to the control in yield of seed per plant, in addition to good quality fibre extracted from them. The ultimate plant height and the time taken for first flowering were found to be negatively correlated.

Radiation induced morphological mutant of jute

SummaryTreatment of dry seeds ofCorchorus capsularis L. var. ‘D. 154’ with 18,000 r X-rays resulted in isolation of a true breeding morphological mutation in the X3 generation. The mutant was characterized by being dwarf, bearing small, narrow leaves, half opened flowers, fruits of varying sizes and low seed setting.The frequency and types of chromosomal abnormalities during meiosis in pollen mother cells and pollen grain sterility in the mutant and control plants in the X3 and X4 generations were studied. The regular occurrence of various types of meiotic abnormalities in a number of mutant generations was probably due to the presence of a mutated. gene or a number of genes.The inheritance of the mutant characteristic was apparently controlled by a recessive gene. The failure of formation of normal fruits and seeds was due to disturbances in megasporogenesis also.

RADIATION-INDUCED CRINKLED LEAVES IN JUTE

Crinkled leaf chimeras appeared regularly, as phenocopies, in the X1 and P1 generations of three varieties ofCorchorus olitorius L. The S1 populations were devoid of this abnormality. These plants were also characterized by late flowering and reduction in the number of flowers per plant. The frequency of crinkled leaf chimeras increased with increase in dosages of X-rays and32P beta rays. Inheritance studies revealed no immediate genetic background of these abnormal plants. However, mutations showing crinkled leaves were isolated in some X3 and P2 lines and their segregation in later generations was found to be disturbed. Chromosomal abnormalities during meiosis were considered as one of the factors responsible for the disturbed segregation. Crinkled leaf mutations also showed variable manifestation of the mutant characteristic in different years.Crinkled leaf chimeras appeared regularly, as phenocopies, in the X1 and P1 generations of three varieties ofCorchorus olitorius L. The S1 populations were devoid of this abnormality. These plants were also characterized by late flowering and reduction in the number of flowers per plant. The frequency of crinkled leaf chimeras increased with increase in dosages of X-rays and32P beta rays. Inheritance studies revealed no immediate genetic background of these abnormal plants. However, mutations showing crinkled leaves were isolated in some X3 and P2 lines and their segregation in later generations was found to be disturbed. Chromosomal abnormalities during meiosis were considered as one of the factors responsible for the disturbed segregation. Crinkled leaf mutations also showed variable manifestation of the mutant characteristic in different years.

Radioresistance of experimentally-produced hybrid of indian spinach (Beta palonga basu & mukherjee)

Abstract An experimentally-produced hybrid between red and green plants of Beta palonga and the segregating population in F 2 showed more resistance to acute X-irradiation of seed than did their parents, as measured by seed germination, plant height, abnormal plant growth, chromosomal abnormality during meiosis and pollen grain sterility. In every measurement the F 2 plants were more sensitive than the F 1 hybrid. The radiosensitivity could not be interpreted in terms of average interphase chromosome volume. The resistance of the hybrid is suggested to be due to factors associated with heterozygosity and heterosis, although this has not been definitely established.

The induction of grain size and colour mutations in rice (Oryza sativa L.) by radioisotopes.

SummarySeven mutants with changes in grain size and in pigmentation of various organs were isolated in the M2 and M3 generations of the Patnai variety of winter rice after treatment with 32P and 35S. Some of these could be useful for breeding.The narrow grain mutant, isolated in the M3 generation after treatment with 32P, was high-yielding and had fine grains and an increased number of long panicles.Two short grain mutants with changed husk colour were obtained in the M2 generation after treatment with 32P. One was also early maturing.One purple apiculus and three purple husk mutants were isolated in the M2 generation after treatment with 35S. Some of these also had reduced plant height and short grains. The purple apiculus mutant bred true for stigma and apiculus colour, but segregated for leaf sheath colour. In purple husk mutants the segregation of mutant characteristics was unusual and there was manifestation of new characters.