Production of Doubled Haploids in Onion: A Review

Onion suffers from high inbreeding depression and, as a result, inbreds that are developed lack genotypic and phenotypic uniformity. Gynogenesis has emerged as a potential strategy to address this drawback. Efforts have been made since the 1980s for identifying highly-responsive genotypes and for overall improvement of the protocol for bettering gynogenic frequency in onion. Besides improving media composition, identification of responsive explants and increasing the chromosome efficiency has remained a major area of focus over the years. This article purports to review progress made thus far in the induction of gynogenic haploids in onion, and challenges/opportunities associated with it

Studies on Genetic Variability and Heritability in Bulb Onion (Allium cepa L.) in North-Western Plains of India

A study on genetic variability, heritability and genetic advance was carried out in bulb onion for 13 traits using 43 accessions. The range of variation was highest for bolting (0 to 51.30%), followed by days to maturity (110 to 155 days) and bulb weight (44 to 87.03g). Values for phenotypic coefficient of variation were higher than corresponding genotypic coefficient of variation for all the characters studied. Higher heritability estimates were obtained for plant height, leaf length, days to maturity, number of scales per bulb, polar diameter, equatorial diameter and TSS. Bolting, bulb weight, neck-to-bulb ratio and the lachrymatory factor showed moderate heritability, while, lowest values were observed for leaf girth and number of leaves per plant. Genetic advance varied from 0.06 to 21.82 for leaf girth and bolting, respectively

Plant regeneration in eggplant (Solanum melongena L.): A review

Eggplant is highly responsive to various tissue culture techniques. Somatic embryogenesis and direct organogenesis are widely studied protocols in this crop, but potential of regeneration varies with genotype, explant and culture media supplemented with different combination and concentration of growth hormones. The genotype is the most important factor affecting somatic embryogenesis and organogenesis. Embryogenic competence  occurs even within explant segments. Among growth regulators, auxins and cytokinins are of more significance as their ratio determines callogenesis,rhizogenesis, embryogenesis and regeneration in eggplant. Organogenesis and somatic embryogenesis related gene expression has been studied and transcripts have been analyzed through molecular studies. Efficient plant regeneration protocols would make a platform for exploitation of usefulsomaclonal variations, mutation breeding, induction of di-haploids, and genetic transformation with economically important genes for the improvement of eggplant.Key words: Callus, somatic embryogenesis, organogenesis, hypocotyl, cotyledon, leaf

Effect of Seed Disinfectants on in vitro Seed Germination and Seedling Development in Eggplant

The present investigation reports effects of disinfectants on culture contamination, seed germination and seedling growth in eggplant. Mercuric chloride hampers seed germination when seeds are treated with 0.1% solution above 2 min duration and lesser durations are not helpful in controlling in vitro contamination. The highest seed germination (89.97%) was recorded with 50% commercial bleach for 20 min in the genotype BL-3, followed by BR-16 (88.53%), BR-14 (86.19%), BL-5 (86.16%) and BSR-23 (85.57%). However, least number of seeds germinated in BR-18 (10.94%), BSR-25 (13.27%) and BL-7 (18.62%) when disinfected with 75% commercial bleach for 25min. Overall results revealed that 50% commercial bleach concentration (73.76%) was better than 75% (36.85%), and 20 min duration (60.82%) was better than 25 min (49.80%) for seed disinfection. Among the varieties, BL-3 was at the top (68.85%) and BR-18 at the lowest (34.16%) edge for per cent seed germination. Seedling growth (cm) with use of commercial bleach was quite satisfactory compared to disinfection with HgCl2, where, 50% commercial bleach favored a good stand of plant lets even after 10 days, showing a healthy root (3cm), hypocotyl (5cm) and cotyledons (1.5cm)

Genetic variability in CMS backcross generations and their maintainers in eggplant (Solanum melongena L.)

Twelve genotypes of eggplant in BC3, BC4 and BC5 generations of CMS-lines derived from Solanum ae-thiopicum × Solanum melongena cross along with their maintainers were evaluated for eighteen quantitative charac-ters at Punjab Agricultural University Ludhiana. Analysis of variance depicted significant variation (P ? 0.05) for all the characters in all generations. High PCV and GCV values were observed for fruit length, fruit girth, fruit weight, number of fruits plant-1 and yield plant-1 in all generations indicating high variability in the germplasm. High heritability coupled with high genetic advance was found for peduncle length, fruit length, fruit girth, fruit weight, number of fruits plant-1 and yield plant-1 in all generations indicating the predominance of additive gene action for these traits. Thus, selections can be made from present germplasm for the development of improved CMS inbred lines with varying fruit traits

Corporate Efficiency, Profitability, and Value Changes after the IPO

This study compares the profitability, operational efficiency, and firm value over the 1985-1990 period of 100 firms that had IPOs in 1985 compared to a matched sample of similar firms which had their IPO before 1980. We find that the 1985 IPO firms were more profitable, operationally more efficient, had more liquid assets, and had greater value over the 1985-1990 period