ENHANCEMENT OF GROWTH AND YIELD QUALITY OF ONION PLANT VIA FOLIAR APPLICATION OF BIO-STIMULANTS UNDER DIFFERENT NITROGEN SOURCES

There are environmental hazards of synthetic nitrogen fertilizers, however, there is a general tendency to raise the yield and quality of strategic crops in Egypt i.e., onion plant. Also, a little is known about the joint effects of different nitrogen sources as soil addition plus foliar spraying with bio-stimulants on onion plants. Thus, this research paper aims to assess the possibility of using compost as a partial substitute for synthetic nitrogen fertilizer with onion plants sprayed with some bio stimulants. During two successive seasons (2020/2021 and 2021/2022), a field trial was performed aiming to evaluate the effect of nitrogen recommended dose (NRD) via different nitrogen sources i.e., plant compost (2.0 %N), ammonium sulphate (21.0%N), urea (46.5%N) and ammonium nitrate (33.5%N) and some bio stimulates on onion plant and some soil properties. The nitrogen treatments [N1:40% of NRD as plant compost +20% of NRD as ammonium sulphate + 20% of NRD as urea+20% of NRD as ammonium nitrate, N2:100% of NRD as ammonium sulphate, N3:100% of NRD as urea and N4:100% of NRD as ammonium nitrate] represented the main plots, while foliar application of bio-stimulants represented the sub main plots, where the foliar application treatments were F1: without (control), F2: liquorice extract (7.50 gL-1); F3: garlic extract (350.0 ml L-1) and F4: yeast extract (7.5 gL-1).The findings indicate that onion plants grown under N1 treatment had growth, yield and quality traits better than the corresponding onion plants grown under other nitrogen treatments, where N2 treatment came in the second order and N3 treatment came in the third order, while N4 treatment came in the last order. Regarding foliar application, the plants sprayed with garlic extract (F3) had the highest values of studied traits followed by that sprayed with liquorice extract (F2) then that spayed with yeast extract (F4) and lately that grown without bio stimulants (F1). Generally, the best performance of onion plants was recorded under N fertilization of 40% of NRD as plant compost + 20 % of NRD as ammonium sulphate + 20 % of NRD as urea+ 20 % of NRD as ammonium nitrate and spraying, simultaneously, with garlic extract. Also, all studied soil properties like soil EC, pH, Om and available N differed due to all studied treatments. Thus, it can be confirmed the possibility of using plant compost as a partial substitute for mineral N fertilizer with onion plants sprayed with some bio stimulants.