POSITIVE EFFECTS OF CO-CULTIVATION OF ENDODIAZOTROPHS ON GROWTH CHARACTERISTICS OF SUGARCANE

摘要

Aims: To observe co-cultivation effect of diazotrophic bacteria on growth characteristics of sugarcane. Methods and Results: The sugarcane seedlings were co-cultivated by using various strains of endophytic bacteria viz., Gluconacetobacter diazotrophs(LMG, PSL 01), and Herbaspirillum rubrisubalbicans (34-HR) in association with vascular arbuscular mycorhiza (VAM). The mixture of all these strains with VAM was also applied for sugarcane co-cultivation . However control was devoid of all these strains(without using any bacteria /VAM). The experiments were conducted as described by Muthukumarasamy et al (1999). One of the commercial cultivars of sugarcane CoPant 84212 was used for the study. The single cane bud was used for planting. These setts wereplanted in earthen pots having about 5 kg of fumigated soil (pH 7.0). In each pot, 15 ml bacterial broth culture (ca. 10~8 ml~(-1)) and 1 g VAM were added. The bacterial broth culture was applied again after 15 days. The pots were irrigated with tap water. The N-free Hoagland solution was added every after 15 days. The co-cultivation has enhanced plant height, nitrogent content, photosynthetic pigments, nitrate reductase activity and net photosynthetic CO_2 assimilation in a sugarcane variety CoPant 84212. The trend of enhancement of these characteristics continued till 4-5 months after co-cultivation with all combination of endophytes. Afterwards, it has shown a declining trend, but the values have always been higher than the control. The applicationof various strains of endophytes have represented an ability towards better plant growth and performance linked with the crop improvement. Significance of Study: The study shows that large -scale sugarcane co-cultivation practices by using suitable endophytes may enhance eco-friendly biological nitrogen fixation which may prevent an excess application of chemical fertilizer to sustain plant productivity and soil health.