Hormonal priming alleviates salt stress in hot Pepper (Capsicum annuum L.)

Germination and seedling establishment are critical stages in the life cycle of plants especially under stress conditions. Different methodologies have been adopted by plant physiologists in different crops to alleviate salt stress. Seed priming has proven beneficial in this regard in many important agricultural crops. The effect of seed priming with salicylic acid (SA) and acetylsalicylic acid (ASA) in improving seed vigour and salt tolerance of hot pepper seedlings was evaluated. Concentrations over 1.0 mM of ASA or SA showed adverse effects on seed emergence. Seeds primed with SA (0.8 mM) and ASA (0.2 mM) were sown in medium at different salinity levels [0, 3, 6 and 9 dS m-1]. Both, SA and ASA treatments showed significantly better results over the control by improvement in time taken to 50% emergence, final emergence percentage, root and shoot length, seedling fresh and dry weight and seedling vigour. Overall, acetylsalicylic acid exhibited superiority over salicylic acid. Our results indicate that hormonal priming, especially with acetylsalicylic acid, can be a good treatment for hot pepper to enhance uniformity of emergence and seedling establishment under normal as well as saline conditions

Tritrophic interactions between parasitoids and cereal aphids are mediated by nitrogen fertilizer

Host plant nutritional quality can directly and indirectly affect the third trophic levels. The aphid–parasitoid relationship provides an ideal system to investigate tritrophic interactions (as the parasitoids are completely dependent for their development upon their hosts) and assess the bottom up forces operating at different concentrations of nitrogen applications. The effects of varying nitrogen fertilizer on the performance of Aphidius colemani (V.) reared on Sitobion avenae (F.) and Aphidius rhopalosiphi (D.) reared on Rhopalosiphum padi (L.) were measured. Parasitism and percent emergence of parasitoids were positively affected by nitrogen fertilizer treatments while developmental duration (egg, larval, and pupal stages) was not affected by increasing nitrogen inputs. In males and females of both parasitoid species, adult longevity increased with the increasing nitrogen fertilizer. Hind tibia length and mummy weight of both parasitoid species increased with nitrogen fertilizer concentrations, as a result of larger aphids. This study showed that nitrogen application to the soil can have important consequences for aboveground multitrophic interactions