Impact of Certain Safe Treatments on Growth, Productivity and Protection against some Insect Pests of Cowpea Grown under Thermal Stress Condition

Abstract

Climate change threatens the world food security, especially in developing countries such as Egypt because of the impact of global warming on plant diversity and productivity, even plant that is considered warm vegetation e.g., cowpea. Field and storage experiments were conducted at El-Baramoun farm and Mansoura Horticulture Research Station, Dakahlia governorate, Egypt to study the agronomical performance response of cowpea cv. Kafr El -Sheikh-1 grown under high temperature and long photoperiod conditions of late summer seasons of 2017 and 2018 to some natural and safe treatments i.e., neem oil (2.5ml/L), chitosan (CS) at 200ppm, chitosan nanoparticles (CSNPs) at 100 ppm and potassium silicate (K-silicate) at 300ppm and their interactions compared with the recommended synthetic insecticide (lannate) at 75g/100L and unprotected control (tap water). The response of infestation of the pod borer (Etiella zinckenlla), as one of the determinants for yield and quality of green pods in the field and dry seeds in the store, to the assigned individual treatments and a treatment of magnetized sea water + iron (Fe) salts were also concluded. In this work, the subsequent storability and insect damage of dry seeds at the ambient temperature for 5 months were studied in terms of either the effect of prior treatments during the field experiment or the effect of post-harvest treatments i.e., natural essential oils of neem, camphor and thyme at 2.5ml/kg seed in comparison with unprotected control and synthetic insecticide (Celphos 57%) at 50mg/kg seeds.The most important results could be summarized as follows:The physiochemical characterization of chitosan nanoparticles cleared that the nanoparticles have, smooth surface, spherical shape and size about 32 nm.All protected treatments considerably differed in improving the agronomical performance over unprotected control at the two seasons. Both mixed treatments were more effective in this regard, since the treatments of neem oil+ K-silicate combined with either CSNPs or CS were superior in increasing vegetative traits, relative water and total chlorophyll contents, green pod yield (47.5% and 46.6%) and dry seed yield (82.8% and 73% ), respectively over unprotected control. The magnetized sea water + Fe salts recorded the highest reduction in pod borer infestation (82.16%), followed by CSNPs (81.16%) compared with the insecticide (76.14%).Concerning the seed storability as affected by prior treatments during field experiment, mixed treatments were more superior in protecting stored seed, especially neem oil+ K-silicate+ CSNPs treatment which reduced seed damage% and infested seed% from 100% (control) to 7.15 and 6.32 % and to 12.11 and 11.14% in 1st and 2nd seasons, respectively. As for the effect of post-harvest treatments, Celphos 57% was the most effective treatment, since damage% and infested seeds % reduced to 0%, followed by neem and thyme oils (less than 10%).Eventually, foliar spray of neem oil+ K-silicate combined with either CSNPs or CS five times during the growing seasons may introduce integrated solutions for biotic and abiotic stresses during field and storage of cowpea. Also for the best stored seeds at the ambient temperature for 5 months, neem and thyme oils (2.5ml/kg seed) are the most recommended natural and safe applications.