Ploidy manipulation in guinea grass (Panicum maximum Jacq., Poaceae) utilizing a Hybridization-supplemented Apomixis-components Partitioning Approach (HAPA)

Ploidy manipulations are achieved by utilizing unreduced gametes, somatic chromosome doubling or haploidization. Apomixis, the asexual mode of reproduction through seeds, involves two of these phenomena viz., apomeiosis (unreduced embryo-sac formation) and parthenogenesis (fertilization-independent embryogenesis). The two components when partitioned may yield high frequencies of triploids and haploids, and thus, serve as a tool to manipulate ploidy levels when appropriately supplemented with hybridization schemes. Utilizing this H ybridization-supplemented A pomixis-components P artitioning A pproach (HAPA), the largest ploidy series in a crop plant was generated in guinea grass ( Panicum maximum Jacq.). Eighty-nine diverse guinea grass accessions were characterized for their reproductive capacities to identify tetraploid (2 n  = 4 x  = 32) accession(s) with high apospory but reduced parthenogenetic capacity, thereby producing a high frequency of hexaploid seeds. Seeds from accession IG 04-164 were utilized to produce a ploidy series by appropriately combining partitioned apomixis components and hybridizations in two seasonal cycles. We successfully obtained plants representing ploidies 3 x, 4 x , 5 x , 6 x , 8 x and 9 x , all derived from a single 4 x progenitor. Production methodology, reproducibility and utilization of HAPA in cytogenetic and molecular studies are discussed.     

Malathion toxicity: Skeletal deformities in zebrafish (Brachydanio rerio,cyprinidae)

Toxicity tests reveal that the zebrafish (Brachydanio rerio) is very sensitive to malathion, an organophosphorus insecticide, and 24 to 96-h LC₅₀ values showed a gradual decrease as the exposure time was increased. Zebrafish exposed to long-term sublethal concentrations failed to spawn and invariably exhibited skeletal deformities. Possible causes of the reduced gonadosomatic index and skeletal deformities are discussed.     

Effect of botanical extracts on the biological activity of granulosis virus against <Emphasis Type="Italic">Pieris brassicae</Emphasis>

A granulosis virus strain infecting Pieris brassicae (PbGV) was isolated from the dry temperate region of northwestern Himalayas as a potential microbial agent for its management. The effect of different botanicals (having insecticidal action against P. brassicae) on the bioefficacy of PbGV was evaluated under laboratory conditions using leaf disc bioassays on cabbage for improving the insecticidal performance of the PbGV. The synergistic action of different botanical extracts was evident in terms of reduction in LC₅₀ values against different botanical extracts. Among different extracts, petroleum-ether extract of neem seed kernel (NSK) when combined with PbGV resulted in maximum reduction of LC₅₀ value (4.39 × 10² occlusion bodies [OBs] ml⁻¹) followed by methanolic extract (7.38 × 10² OBs ml⁻¹) and aqueous extract (9.36 × 10³ OBs ml⁻¹) as compared with PbGV alone (1.85 × 10⁴ OBs ml⁻¹) for 2nd instar larvae of the test insect. These trends were found analogous in cases of 3rd and 4th instars of P. brassicae with different solvent extracts of NSK. The other botanicals evaluated, viz., Eupatorium and Artemesia, also resulted in reduction of LC₅₀ values for 2nd, 3rd and 4th instars as compared with PbGV alone when different extracts were combined with virus for bioassays. The studies suggest that the PbGV in combination with botanical pesticides could be more useful as a bio-pesticide against cabbage butterfly (P. brassicae) in IPM programs.     

ENHANCEMENT OF PEA PRODUCTION USING LEAF EXTRACT OF WITHANIA SOMNIFERA L. UNDER SUB-TROPICAL FIELD CONDITIONS OF KULLU,NORTHWESTERN HIMALAYA,INDIA

The present study investigates the promoting effects of leaf extract of Withania somnifera L plant on growth, biomass, and yield of Pisum sativum L plants. The growth and biomass of pea plants increased significantly over control due to leaf extract (LE-WS) treatment. Pea plants treated with LE-WS and ascorbic acid (L-AA) showed higher number as well as total dry weight of nodules over the control. The economic yield of pea plants due to LE-WS and L-AA treatments increased by 84 and 114%, respectively over control. The economic yield was significantly correlated with number of nodules (R² = 0.75, P <0.001). The study suggests that LE-WS may be used to promote the growth and increase the production of pea plants in areas having multiple stresses. Detailed study on the use of extracts of medicinal plants as a tool to reduce the adverse effects of single stress is further required.     

Classification of features selected through Optimum Index Factor (OIF) for improving classification accuracy

The present investigation was performed to determine if the features selected through Optimum Index Factor (OIF) could provide improved classification accuracy of the various categories on the satellite images of the individual years as well as stacked images of two different years as compared to all the features considered together. Further, in order to determine if there occurs increase in the classification accuracy of the different categories with corresponding increase in the OIF values of the features extracted from both the individual years’ and stacked images, we performed linear regression between the producer’s accuracy (PA) of the various categories with the OIF values of the different combinations of the features. The investigations demonstrated that there occurs significant improvement in the PA of two impervious categories viz. moderate built-up and low density built-up determined from the classification of the bands and principal components associated with the highest OIF value as compared to all the bands and principal components for both the individual years’ and stacked images respectively. Regression analyses exhibited positive trends between the regression coeffi- cients and OIF values for the various categories determined for the individual years’ and stacked images respectively signifying the prevalence of direct relationship between the increase in the information content with corresponding increase in the OIF values. The research proved that features extracted through OIF from both the individual years’ and stacked images are capable of providing significantly improved PA as compared to all the features pooled together.     

Development and characterization of interspecific hybrids of Trifolium alexandrinum×T. apertum using embryo rescue

This is the first report on the development of interspecific hybrids between Trifolium alexandrinum and T. apertum using embryo rescue and characterization of F₁ plants. T. apertum was used as the male parent and T. alexandrinum as the female parent. Development of interspecific hybrids under natural conditions is not successful and so embryo rescue was attempted. Of the several combinations tried, pollination 2 days after emasculation and embryos rescued 11 days after pollination was found to be the best. For embryo culture, EC3 medium consisting of MS basal supplemented with 2.3 μM kinetin and 3% sucrose was used. Germinated embryos were transferred to LSP3 medium 25 days after inoculation wherein most of the cultures showed multiple shoots that were split and subcultured on RL1 medium for rooting. After hardening, about 75% of hybrids were successfully transferred to the field. The hybrids, in general, showed morphological traits intermediate between the two parents; however, a few hybrids showed better growth than either parent. Some F₁ plants were almost 3 weeks later in flowering than the female parent. Pollen fertility among these plants ranged from 78 to approximately 100%. Chromosomal associations at diakinesis and isozyme banding patterns for acid phosphatase (ACP), superoxide dismutase (SOD) and peroxidase also confirmed the hybrid nature of the plants.     

Pollination behaviour among different breeding populations of Egyptian clover

Pollination behaviour and the extent of self‐compatibility were studied in Trifolium alexandrinum, commonly known as Berseem or Egyptian clover, an important fodder legume cultivated in Egypt, the Mediterranean basin and the Indian subcontinent. Four treatments were imposed on 16 populations comprising three diploid exotic, three diploid advanced breeding, five induced tetraploid and five diploid pentafoliate lines. The different treatments were open pollination, caging, hand tripping and controlled bee visits. Compared with the open pollinated condition, reduction in seed set in different populations ranged from 12.3 to 99.2% under caged condition. Eight of 16 populations registered more than 90% reduction in seed set. Hand tripping and/or controlled bee visits improved seed set considerably in a few populations, whereas, in one population, no significant effect of these four treatments was observed. The results indicated considerable variation for self‐compatibility, together with a requirement of tripping for pollination and seed set, even in self‐compatible lines.