Nitrogen Sources and Algae Extract as Candidates for Improving the Growth, Yield and Quality Traits of Broccoli Plants

Abstract

Increasing consumer awareness has contributed in establishing food safety issues and environmental concerns through introducing organic and bio-approaches as substitutes for the traditionally chemical fertilization. However, the efficiency of these fertilizers seemed to be relatively low when compared with the traditional mineral fertilizers. This study postulates that algae extracts of Chlorella sp. might stimulate the growth of plants. To examine this assumption, a field study was conducted for two successive seasons (2015/2016 and 2016/2017) using different N-sources e.g. organic (compost), bio (Azotobacter chroococcum and Azospirillium lipoferum) and mineral (ammonium nitrate) fertilizers with or without algeal extracts of Chlorella sp. to investigate their efficiency for improving the growth parameters and yield components of broccoli plants grown on a sandy loam soil. Results reveal that the highest increases in uptake of NPK were attained for the application of "compost + ammonium nitrate + biofertilizer". Such improvements resulted in concurrent increases in plant height, number of leaves per plant, leaf area; shoot fresh weight, chlorophyll a and b, curd weight and diameter, vitamin C, TSS, total phenol and antioxidants content in broccoli heads and the outcome head yield. Moreover, the combination between different N-sources and foliar spray of alga extract resulted in further significant increases in NPK uptake by plants and this in turn improved significantly, the abovementioned growth parameters and yield components. Accordingly, our results support the hypothesis indicating that algae extracts improved significantly the growth parameters and yield components of broccoli plants grown on a sandy loam soil.