Optimizing Protein-Rich Young Vegetative Quinoa (Chenopodium quinoa) Growth: Effects of Inter-Row Spacing and Genotype in Mediterranean Summer Cultivation

Young vegetative quinoa (YVQ) has gained attention as a high-protein leafy crop for human consumption with potential for cultivation in Mediterranean and semiarid regions. We investigated the effects of inter-row spacing and genotype on YVQ fresh and dry matter (DM) yield, protein content (PC), and protein yield during summer cultivation in northern Israel in two separate, independent, randomized field experiments over two consecutive years (2020–2021). We hypothesized that row spacing and genotypic differences would significantly impact yield and PC. Inter-row spacing significantly affected plant density, ranging from 55 to 366 plants m−2. Fresh and DM yields ranged from 4957 to 28,469 kg ha−1 and 661 to 3737 kg DM ha−1, respectively. PC ranged from 20.5 to 26.6% and was not significantly influenced by row spacing. Total protein yield ranged from 147 to 884 kg ha−1. Among the five tested genotypes, no significant differences were observed in fresh (7477–17,776 kg ha−1) or dry (1122–2199 kg DM ha−1) biomass, PC (21.2–26.5%), or protein yield (260–579 kg ha−1), suggesting limited genetic differentiation under the specific environmental and agronomic conditions tested. Amino acid analysis confirmed the presence of all nine essential amino acids, fulfilling over 30% of the recommended daily intake per 100 g DM. These findings highlight YVQ as a promising, sustainable, and protein-rich leafy crop for Mediterranean agriculture. Further research should explore multi-harvest potential, mechanical weeding, and optimized agronomic practices for commercial-scale production.