EFFECT OF SOWING TIMES AND MUSTARD VARIETIES ON THE INCIDENCE OF APHID

Abstract

The study on the effect of sowing times and varieties on the incidence of mustard aphid was conducted at the experimental field of Sher-e-Bangla Agricultural University, Dhaka during the winter season from November, 2013 to February, 2014. The experiment was laid out in two-factorial randomized complete block design with three replications. Eight mustard varieties such as V1 (Tori-7), V2 (BARI Sharisha-6), V3 (BARI Sharisha-9), V4 (BARI Sharisha-11), V5 (BARI Sharisha-13), V6 (BARI Sharisha-14), V7 (BARI Sharisha-15) and V8 (BARI Sharisha-16) sown in three sowing times considering 7 days interval such as S1 (9 November, 2013), S2 (16 November, 2013) and S3 (23 November, 2013) were studied in terms of aphid infestation on plants, inflorescence and pods aiming to find out the tolerant variety(ies) against aphid as well as effective sowing time(s) to escape aphid infestation. Out of eight mustard varieties, Tori-7 was found as the most preferred host for aphid infestation followed by BARI Sharisha-9, where as BARI Sharisha-13 performed as least preferred varieties in terms of aphid infestation on plants, inflorescence, and siliqua. On the other hand, out of three sowing times, late sowing (23 November) was found as the most suitable for aphid infestation followed by 16 November, where as the earliest sowing time (9 November) was found as the worst for aphid infestation on mustard whatever the variety was cultivated. The most aphid susceptible variety Tori-7 produced the lowest grain yield per hectare followed by BARI Sharisha-9. Conversely, the least aphid susceptible variety BARI Sharisha-13 produced highest grain yield per hectare. From the combined effect, the study revealed that the BARI Sharisha-13 manifested the lowest aphid infestation and produced highest yield when sown at early season (9 November). Conversely, Tori-7 manifested the highest aphid infestation and produced lowest grain yield when sown in late season (23 November).