Effects of sulfur fertilization on yield, biochemical quality, and thiosulfinate content of garlic

Abstract

In the present study, three field experiments were conducted to study the effect of sulfur (S) fertilization on yield and biochemical quality of garlic as well as S uptake and thiosulfinate concentration in garlic during the period 2014-17. The experiment consisted of six S treatments (0, 15, 30, 45, 60 and 75 kg S ha?1), and each treatment was replicated four times. The yield, total protein concentration, concentrations of allicin and other thiosulfinate, and antioxidant activity were increased at S doses of 15, 30, and 45 kg ha?1, however, a decline was observed in the aforementioned parameters at 60 kg ha?1 and 75 kg ha?1. At doses 60?75 kg ha?1, S uptake increased whereas the nitrogen-to-sulfur ratio decreased. The concentrations of total protein, allicin, pyruvic acid, and total phenol increased significantly with S application in 2015-16 compared to those in 2014-15 and 2016-17, and the percentage increase varied from year to year. The concentrations of pyruvic acid, total S, allicin and other thiosulfinates, and total polyphenol exhibited strong positive relationships with the dose of S, although the higher yields did not necessarily increase with the S dose. Consequently, a judicious application of S is required to increase the yield and improve the quality of garlic.