Merajul Islam Robab

Effect of different inoculum levels of Meloidogyne incognita on growth and yield of Lycopersicon esculentum, and internal structure of infected root

Lycopersicon esculentum (tomato) plants, grown in sterilised clay pots, were inoculated with 50, 500, 1000, and 3000 second-stage juveniles (J2) of the root-knot nematode (Meloidogyne incognita) and were kept in a greenhouse. A non-significant reduction in plant growth and yield was noticed in T1 plants. Significant reductions in plant growth and yield were found in T2, T3, and T4 plants. Highest reductions, in growth and yield, were observed in T5 plants. Transverse and longitudinal sections revealed that M. incognita traversed through the cortical tissues of the root, caused infection in the differentiating vascular tissues and successfully established in the infected roots. The post-infection changes in the affected parts were hypertrophy and hyperplasia, around the head of the nematodes. Five to 10, among the hypertrophied cells, developed into very large, multinucleate, prominent, and highly specialised giant cells. The nuclei in each giant cell enclosed one or more nucleoli. Xylem and the phloem strands were found to be disoriented. Abnormal xylem and phloem comprised a substantial portion near the giant cells. The metabolic changes in the affected part led to the formation of galls, characteristic of the root-knot infection.

Histopathology of roots of Glycine max (L.) Merrill induced by root-knot nematode (Meloidogyne incognita)

In Glycine max, the second-stage juveniles of Meloidogyne incognita entered the roots through the apical meristem or elongation zone. The juveniles induced giant cells in the zone of vascular strands. Near the head of the nematode and adjacent to the giant cells, the vascular strands exhibited abnormalities in their shapes and structures; both xylem and phloem were found to be affected. The giant cells had dense and granular cytoplasm, and large nuclei with large nucleoli. Some parenchyma cells exhibited hypertrophy, while others exhibited hyperplasia. The distinctive feature of the study is reporting the occurrence of abnormal xylem, abnormal phloem and abnormal parenchyma.

Interaction between Meloidogyne incognita and Pochonia chlamydosporia and their effects on the growth of Phaseolus vulgaris

An experiment was conducted to test the effect of different doses of 2, 4 and 8 g/2 kg of soil of Pochonia chlamydosporia against the root-knot nematode (Meloidogyne incognita) on Phaseolus vulgaris. It was observed that inoculation of plant with the nematode alone, and 15 days prior to fungal inoculation, reduced the plant growth when compared with the plant with fungal application followed by the nematode. Plant length, fresh and dry weight, chlorophyll, carotenoid, protein contents and nitrate reductase activity decreased in nematode-infested plants. Application of higher dose of 8 g/2 kg of soil of P. chlamydosporia increased all the plant growth parameters as well as biochemical parameters. Highest number of galls per root system was recorded on the plants infested with nematode but not treated with the fungus. However, application of fungus prior to nematode inoculation improved the plant growth and reduced the number of galls and the number of egg masses per root system.

Induced variations in quantitative traits by EMS and SA treatments in Linum usitatissimum L.

The Linum usitatissimum L. var.NDL-2002 has high oil yield potential. The seeds of the variety were exposed to different concentrations (0.02–0.10%) of ethyl methane sulphonate (EMS) and sodium azide (SA). Observations on germination, germination inhibition, morphology, plant height, yield parameters, branches per plant, etc. were recorded in M1 generation in control and treated plants. Leaves notching, effect on internodal length were observed and also the more adverse effect of EMS was observed than SA.