EXPLORING THE DIVERSITY OF CYANOGENIC POTENTIAL IN SORGHUM (SORGHUM BICOLOR (L.) MOENCH) AT DIFFERENT GROWTH STAGES THROUGH TREND ANALYSIS
BALASAMY JAYARAMAN KARTHIKEYAN, CHAKRAPANI BABU AND JOHN JOEL AMALRAJ
Department of Plant Genetic Resources, Centre for Plant Breeding & Genetics
Tamil Nadu Agricultural University,
Coimbatore-641 003 (Tamil Nadu), India
*(e-mail : bjkarthi@gmail.com)
(Received : 7 June 2017; Accepted : 21 December 2017)
SUMMARY
The cultivated species of sorghum is a very high valued fodder crop. However, it cannot be used as feed until it reaches its maturity stage as its high cyanogenic potential (HCNp) poses various
threats to the ruminants when fed as fodder. This research focuses on understanding the dilution pattern of dhurrin and identifying safe forage sorghum lines to avert its poisoning behaviour. Sorghum accessions were screened for HCNp through Feigl-Anger densitometry tests. Picrate paper test was performed to select ideal genotypes with low HCNp through trend analysis at various crop growth stages of 8th (seedling), 35th (vegetative) and 50th (flowering) days after sowing. The reference set accessions were evaluated for their fodder yielding traits viz., plant height, stem girth, number of tillers, number of leaves, leaf length, leaf breadth, leaf-stem ratio, green fodder yield per plant and dry fodder yield per plant. Variability and association studies showed selection for fodder potential could be focused on the traits green fodder yield, dry fodder yield per plant and plant height as they exhibited high heritability; genetic advance and strong association. Trend analysis indicated a downward trend of HCNp proving that dhurrin dilutes as the crop ages. There were genotypes performing superior to K 11, but K 11 recorded low HCN content on the 8th day; showed a gradual dilution towards 50th day and had high GFY. Consequently, K 11 was selected as the ideal genotype for low HCNp and high fodder yield. Moreover, the accessions K 3 and TKSV 1050 showed superior performance for fodder potential over the local check and could be adopted for general cultivation. Of the various methods followed the rapid screening assay proved successful for screening large number of accessions efficiently and rapidly. The traditional biochemical method though efficient is time consuming and laborious, whereas the picrate paper test is effective in screening the accessions even at field level.
Key words: Sorghum, Fodder, Cyanogenic potential, Feigl-Anger densitometry, Picrate test