The Effect of Sulfur Fertilizer on Glucoraphanin Levels in Broccoli (B. oleracea L. var. italica) at Different Growth Stages

Abstract

Three sulfur (S) treatements were imposed by applying gypsum to three broccoli cultivars (Claudia, Marathon, and TB-234) known to differ in glucoraphanin content of mature seeds. The S treatments were control (very low added S), low S (23 kg S ha(-)(1)), and high S (92 kg S ha(-)(1)). The gypsum applications during the early vegetative phase of the three broccoli cultivars increased S uptake and the glucoraphanin content in each plant organ. There were significant genotypic differences for the content of both S and glucoraphanin in all plant organs at different growth stages with gypsum applications. A large increase in S and glucoraphanin content was found in the green heads of broccoli and mature seeds. S present in glucoraphanin accounted for only 4-10% of total S content in broccoli heads. However, S present in glucoraphanin in mature seeds accounted for 40-46% of the total S in the seeds of moderate and high glucoraphanin cultivars (Marathon and TB-234). The partitioning of S into glucoraphanin also increased with gypsum applications. Differences in S uptake, S distribution between organs, and partitioning of S into glucoraphanin largely explained the differences in glucoraphanin content in the green heads and mature seeds for the three broccoli cultivars and three S treatments.

Agricultural practices for enhanced human health

“…However, other comparative studies of substrates and soil, with tomato plants, revealed that the concentrations of b-carotene, lycopene and lutein in fruits were almost halved when the plants were grown in rockwool (Petersen et al 1998) or perlite (Stamatakis et al 2003), compared with plants grown in soil (De Pascale et al 2001). Also, in broccoli plants grown in a mixture of silica sand, white peat and clay, a total concentration of glucosinolates three times lower than when plants were cultivated in soil was obtained (Rangkagilok et al 2004;Schonhof et al 2007). However, in other work no differences between substrates and soil have been reported.…”

“…However, differing effects were observed for specific glucosinolates (Aires et al 2006): some of the N and S fertilisation combinations had a detrimental effect on the level of aliphatic glucosinolates in broccoli sprouts whereas higher concentrations of indole and aromatic glucosinolates were obtained. Also, Rangkagilok et al (2004) studied the effect of sulphur fertiliser in three broccoli cultivars, showing an increase of total S and glucoraphanin accumulation in these cultivars during plant development, with a large increase in broccoli heads and mature seeds. However, different results were obtained with flavonoids, since they strongly decreased.…”

Minimal nitrogen and water use in horticulture: Effects on quality and content of selected nutrients

“…Glucosinolate synthesis in broccoli requires optimal (i.e. high) S (Rangkadilok et al, 2004). Once S supply is adequate, however, minimal N applications resulted in highest glucoraphanin content in broccoli (Table 1) (Jones et al, 2007), but N application rates that optimized glucoraphanin content in broccoli resulted in a significant decline in head weight (Jones et al, 2007) In a study with higher N application rates (50-600 kg ha À1 ), Omirou et al (2009) found glucoraphanin content in broccoli florets was maximized with a mid-range N application of 250 kg ha À1 .…”

Handbook of Plant Food Phytochemicals

“…Marathon but had no significant effect on two other cultivars [139]. In the study of Jones et al (2007) S application at levels of 50 and 100 kg/ha had no significant effect of glucosinolate or flavonol accumulation [75].…”