Morpho-biochemical and nutritional value of some early- and late-bolting spinach (Spinacia oleracea) accessions

Spinach (Spinacia oleracea L.) is a well-known leafy plant with valuable nutritional properties. The nutritional and marketing values of vegetables are highly affected by bolting. So far, researchers have studied the morphological properties of spinach, but its traits and characteristics in accessions with different bolting times have not been comprehensively studied. Therefore, the study was carried out to investigate the variations in morpho-biochemical characteristics of different spinach accessions based on bolting time. This study aims to find out whether or not bolting time causes morpho-biochemical changes in different spinach accessions. Here, "Varamin 88", "Matador", "D'inverno", "Viroflay" and "Spinagh" were used as late-bolting accessions groups, while "Lorestan" and "Kashan" were applied as early-bolting accessions groups. This spring field experiment was set up in a complete randomized block of 3 replicates and 18 observations. The results revealed significant differences between the early- and late-bolting spinach accessions (comparisons between groups) in their leaf number, plant height, yield, fresh and dry shoot weight, day to bolting, flavonoid, phenol, vitamin C, carbohydrate, nitrate, calcium (Ca), and iron (Fe) content. Late-bolting spinach group had more leaf numbers (23.9% increase), yield (64.3% increase), fresh and dry shoot weight (56.4% and 74% increase), day to bolting (55.9% increase), flavonoid (40.6% increase), phenol (37% increase), vitamin C (7.2% increase), and nitrate (37% increase), while early-bolting spinach group only had more plant height (45.9% increase), carbohydrate (21.8% increase), calcium (87.5% increase), and iron content (more than 100% increase). The biplot analysis showed the superiority of the late-bolting spinach accession dry and fresh weight, flavonoid, phenol, and vitamin C in spring planting. Conclusively, it was found that early-bolting spinach accessions were taller in leaf and petiole form, which is an advantage for mechanized harvesting. Late-bolting spinach accessions, particularly "Viroflay" and "Varamin 88" among the non-Iranian and Iranian masses, respectively, were preferred for spinach production and biochemical features, according to PCA and cluster analysis. This study recommends that if the quantity of production is important, the farmers use late-bolting plants for cultivation, and if mechanization is important, they use early-bolting plants for cultivation.