Genetic variability of sugarcane genotypes for red rot disease

Sugarcane is a vital crop grown for sugar and sugary products. The importance of sugarcane has been increased greatly as many countries have started the biofuel production using sugarcane as a source. This crop suffers many diseases caused by bacteria, fungi, and viruses. Red rot is one of the major diseases which limit the yield every year. We have screened six sugarcane genotypes for cane girth, height, sugar recovery, and red rot fungus resistance. All these genotypes are commonly adopted for cultivation locally. The screening was done using manually infecting the cane stalks with fungus inoculum and was graded for their response to the pathogen. The six genotypes (3 resistant and 3 susceptible) showed that there is a strong relationship between the sugar content in cane stalk and fungus propagation i.e., more sugar recovery rate helps the fungus to grow at a faster rate. Fungus usually grows much rapidly towards the aerial parts of the plant as compared to the roots, from the point of infection. Higher girth values also show a strong correlation with disease progression. We have also noted that in resistant cultivars the nodes are much more efficient barriers to let the infection progress to the next internode as compared to susceptible cultivars. The productivity level of sugarcane can be improved by identifying the red rot resistance genes in resistant and susceptible cultivars and use these genes to produce more productive varieties. The coefficient of variation was found lower for all traits which indicated that there was consistency among the results. The average cane height was recorded as 2.48789 ± 0.1185 m, cane weight 9.5033 ± 0.1246 kg, cane girth 2.1522 ± 0.0179 cm and sugar recovery 8.3572 ± 0.0758%. There was a strong and positive correlation of sugar recovery with cane girth, average cane weight and sugar recovery percentage The regression analysis indicated that the cane height showed a negative impact on sugar recovery, while cane weight showed the positive effect to increase sugar recovery. The cane girth showed higher and positive effects to improve the sugar recovery percentage. The selection of crop plant genotypes may be made depending upon the positive and strong correlation of the response variable with independent variables.