Rapid Assessment of Rind Hardness in Sugarcane and Its Association with Biochemical Traits

Rind hardness in sugarcane plays a major role in lodging resistance, and internode borer resistance,screening of sugarcane for rind hardness is essential for reducing yield loss. In order to identify the suitability of soil penetrometer for rapid rind hardness measurement, the rind hardness testing was carried out in two sugarcane clones of different rind hardness variability viz., Co 13003 (hard rind type) and Co 14002 (soft rind type). The investigation was carried out by three methods viz., pendulum type impact test rig, texture analyzer,and soil penetrometer and theresults revealed that thehard rind type Co 13003 sugarcane clone was observed with significantly greater hardness. Significant correlation between the three methods for the rind hardness trait and among the three methods the soil penetrometer method of determination of rind hardness is easy and rapid. Two-way hierarchical cluster analysis of studied biochemical traits has revealed a better classification of hard-rinded and soft-rind sugarcane clones. The Co 13003 was recorded as least susceptible to borers with high rind hardness (>200 psi), along with better fibre. The NG 77 a hard rind type clone was also observed with high lignin compared to soft rind Gungera.

Regulation of urease in Bradyrhizobium colonizing green gram (Vigna radiata (L.) Wilczek).

In the present study attempts have been made to characterize urease expression in slow growing Bradyrhizobium strains TAL442 and MO5 which are endosymbionts of green gram (Vigna radiata (L.)Wilczek). It was found that urease activity in vegetative cells of both the strains was inducible unlike their fast growing counterparts. Mode of regulation in TAL442 was governed by presence of ammonia. Urease expression was also detectable in bacteroids of both the strains which was not influenced by presence of external nickel chloride in high concentration, a situation detrimental to the vegetative cells.

Phage typing of indigenous soybean-rhizobia and relationship of a phage group strains for their asymbiotic and symbiotic nitrogen fixation.

A total of 354 indigenous bradyrhizobia were isolated from soybean nodules collected from five major crop grown regions. Host-specific 12 phages, each active on particular strains were selected. Factors, which influence the interaction between the host and phage, were examined. Four different types of plaques were detected. Nearly 17% of isolates were found resistant to all phages. Phage sensitivity patterns revealed a total of 32 distinct phage genotype groups. Different set of phage combinations expressed variation in specificity for parasitizing against particular group of rhizobia. Distributions of isolates in each phage types differed markedly between regions. Interestingly, nine strains belonging to phage group 16 exhibited high ex planta nitrogenase activity in culture. However, no correlation could be established between high ex planta nitrogenase activity and their symbiotic effectiveness with soybean cultivars. Soybean cv. JS335 showed relatively superior performance than Bragg and Lee with indigenous bradyrhizobial strains. Phage typing revealed the existence of large genetic diversity among native rhizobia and selection of the superior bradyrhizobial strains can also be possible for a given soil-climate-cultivar complex.