Prodeep Kumar Borua

Meiotic behaviour and pollen fertility in three species of Zephyranthes (Amaryllidaceae)

Studies on meiotic behaviour and pollen fertility have been carried out in Zephyranthes candida, Z. grandiflora and Z. flava. Maximum meiotic abnormalities in chromosome behaviour were observed in Z. candida and Z. grandiflora. There were variations in the number of bivalent formation, multivalents and anaphasic separation. All types of abnormalities were found to be associated with low percentage of pollen fertility. In Z. flava, chromosomal aberrations were low and pollen fertility was high.

Failure in an interspecific cross between Solanum khasianum Clarke and Solanum mammosum L.

SummaryAttempts to obtain a successful interspecific cross between Solanum khasianum Clarke and Solanum mammosum L. were unsuccessful, and the probable reasons for this failure were investigated. A reduced number of viable pollen grains and low receptivity of the stigmas of S. mammosum L. and heterostyly in both species are the probable reasons for the failure of the attempted interspecific crosses between S. khasianum Clarke and S. mammosum L.

Improved micropropagation and in vitro fruiting of Morus indica L. (K-2 cultivar)

A rapid economically viable micropropagation protocol has been developed in the present work for Morus indica L. (K-2 cultivar) utilizing the readily available nodal explants. Explants were established on different plant growth regulators (PGRs) either individually or in combinations. MS medium containing 1 mg L−1 Kinetin (Kin) showed the best shoot multiplication with 4.8 ± 0.23 cm average shoot length and 6.5 ± 0.03 number of internodes. Regenerated shoots were elongated in MS medium supplemented with 1.5 mg L−1 gibberellic acid (GA3). Elongated shoots cultured in full-strength MS medium supplemented with 1 mg L−1 2,4-dichlorophenoxyacetic acid (2,4-D) for one week and then cultured in half-strength MS proved to be more effective in rooting compared to other PGRs in significantly shorter duration. Micropropagated plants transferred to soil fortified with the quarter-strength of MS salts along with humidity regulation process showed 89% survival frequency. In vitro flowering in the regenerated shoots was also observed in the MS medium supplemented with (1.5 mg L−1) Kin and carbon source replaced by commercial sugar cubes. This method can be effectively used for in vitro culture of M. indica in commercial scale owing to its enhanced quality and reduced time frame.

GA3 Assisted Seed Dormancy Breaking in Abelmoschus moschatus Medik. subsp. moschatus

Abstract Abelmoschus moschatus Medik. subsp. moschatus is a wild uncultivated variety of common lady’s finger (Abelmoschus esculentus) possessing a high degree of seed dormancy. Methods of dormancy breaking in the seed of the plant were investigated through different physical and chemical methods. Different preconditioning treatments including hot water, dry heat, physical scarification and chemical treatments including exogenous GA3 were applied to explore the initiation in germination. Seeds were germinated under the controlled photoperiod and temperature. The viability of the test seeds was estimated by topographical 2, 3, 5-Triphenyltetrazolium chloride (TTC) solution test. Highest germination percentage was obtained in the seeds treated with the exothermic reaction of H2SO4 and H2O, followed by exposure to gibberellic acid (GA3). The exposure time of exogenously applied GA3 had a significant influence on the germination response. The optimum germination temperature was found to be 30 ± 0.5°C. Treatment with 0.75% of 2, 3, 5-Triphenyltetrazolium chloride solution for 4 h at 35 ± 0.5°C enabled to correlate the viability of the seeds with the germinative values. Maximum germination was induced through this technique and dormancy of the seed can be attributed due to hard impermeable seed coat and endogenous physiological factor.