Sorghum crop (Sorghum bicolor) is considered as a significant crop in Indonesia. Barcelos and team1 reported that ethanol production from sorghum could be 5 times (450 L t–1) more as compared to those from sugar cane (80 L t–1). However, during its development, the supply of sorghum seeds is restrained through weevil pest such as corn weevil (Sitophilus zeamais Motsch.)2 and rice weevil (Sitophilus oryzae)3. These pests cause huge seed damage during its storage. Prevalence of weevils is all over the world but its development is much quicker in the warmer climate of tropical areas4, such as Indonesia.
It is reported that numerous genotypes of sorghum have capability to resist against weevil pests5. However, different seed varieties possess different level of resistance against these enemies. Moreover, physical properties like seed size of sorghum also affects the weevil priority to attack these seeds as weevils have a preference to larger size of seed as compared to smaller one6.
Scientists have introduced many variables to calculate seed resistance to the weevil, such as the %age of seed loss or loss of seed weight, number of weevil in seed lot, developmental period of weevil7 as well seed damage3,8. But, sorting out the level of resistance among different seed varieties is the still the main challenge for genetic engineers, i.e., which genotypes of sorghum in Indonesia possesses high, moderate or low resistance to weevil during storage.
Accordingly, research team led by Eko Pramono9 conducted a research to evaluate the seed resistance of various genotypes of sorghum to weevils during storage, both in high and low temperature through “choice method” based on painter theory. For this purpose, 3 kinds of this particular method (with the challenge, no challenge and control) were utilized to assess the seed resistance to weevil of thirty four genotypes of sorghum in Indonesia. Moreover, randomized complete block design was followed with 3 replications and 2 factors; genotype as well as kind of method.
At the end of this experiment, scientists found three levels of seed resistance against weevil (Sitophilus sp.) among 34 genotypes of sorghum, including high resistance, moderate resistance as well as low seed resistance genotypes. Conclusively, research team suggested that by reducing storage temperature from 26.9-18.1°C seed resistance to weevil (Sitophilus sp.) can be enhanced. Moreover, this temperature range can also lessen the weevil number from 14.0 individuals to 3.7 individuals per 200 seeds. These findings can also assist plant breeders to develop novel sorghum genotypes resistant to weevil and seed producers as well to supply competent sorghum seeds.
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17 November, 2019