Inorganic fertilization of wheat in relation to aphid infestation, natural enemies population, growth and grain yield

A field study was carried out to evaluate the impact of inorganic fertilization to wheat variety Sehar-2006 on aphid infestation, enemies population, growth and grain yield according to randomized complete block design with three replications at Adaptive Research Farm, Vehari during 2009-2010 and 2010-2011. Five NPK doses of 170-0-0 (T1), 170-114-0 (T2), 170-0-62 (T3), 170-114-62 (T4) and 0-0-0 (T5) (Control) kg per ha were tested in the experiment. Average results of the both years showed that NPK doses affected all the growth and yield parameters significantly. Application of 170-114-62 NPK kg per ha gave maximum plant height (110.1 cm), highest germination counts (240.2), increased No. of productive tillers (376.3), highest No. of grains per spike (42.33), heavier grain weight (41.57 g) and maximum grain yield (3732 kg per ha) as compared to recorded with 170-0-62, 170-114-0, 170-0-0 and 0-0-0 (control) NPK kg per ha. Results also indicated that main effects of time of sampling, NPK doses, and their interaction significantly affected aphid and predator population. On 15.03.2010, maximum aphid population per tiller (12) was observed, where 170-0-0 NPK kg per ha was applied followed by (11.78) at 0-0-0 NPK kg per ha as against the minimum (6) with 170-114-62 NPK kg per ha. Maximum aphid population per tiller (7.445) was observed, where 170-0-0 NPK kg per ha was applied followed by (5.963) at 170-0-62 NPK kg per ha as against the minimum (2.852) with 170-114-62 NPK kg per ha recorded on 15.03.11. A highest population of predators per plant (1.259 and 1.562) was observed during 31.03.2010 and 31.03.2011, respectively followed by (1.018) on 22.03.10 and (0.424) on 22.03.2011. Significant negative relationships (R2=-0.86 and -0.75) was depicted between NPK doses and No. of aphids during 2009-2010 and 2010-2011, respectively. Gradual decrease in aphid population was noted when balanced NPK was applied. Significant relationship (R2=0.71 and 0.87) was found between maximum temperature and predators per plant during 2009-2010 and 2010-2011, respectively. Negative correlation (r=-0.82 and -0.57) was observed between aphid population and grain yield during 2009-2010 and 2010-2011, respectively with respect to inorganic fertilization on wheat crop.