Effect of boron stress on yield, biochemical parameters and quality of tomato

摘要

Tomato cv. DL-3 was grown in refined sand at graded levels of boron ranging from deficiency to excess (0.0033 to 3.3 mg B/l). Variation in boron supply influenced the growth of plant which became perceptible after 32 days of sowing. Boron deficiency symptoms (0.0033 mg B/l) were shortening of internodes, affected young leaves were thick, brittle and curled outward. Biomass, weight and volume of fruits were maximum at 0.33 mg B/l. In B deficient tomato leaves, the specific activity of peroxidase, ribonuclease and polyphenol oxidase increased and that of acid phosphatase and phenylalanine ammonialyase decreased. At excess boron (> 0.33 mg B/l), toxicity symptoms appeared on d 51. At 3.3 mg B/l, growth of plants was markedly reduced, old leaves developed marginal necrosis, number and size of lamina reduced. At this level, the specific activity of peroxidase, ribonuclease and acid phosphatase increased and polyphenol oxidase and phenylalaninelyase decreased in tomato leaves. In low and excess B, the concentration of reducing, non-reducing and total sugars and phenols were high in fruits. In fruits, the concentration of starch, ascorbic acid and lycopene decreased in low B and that of ascorbic acid accumulated and lycopene content decreased in excess boron. The concentration of B increased in leaves and fruits with an increase in B supply from low (0.0033 mg B/l) to excess (3.3 mg B/l). The values of deficiency, threshold of deficiency, threshold of toxicity and toxicity were respectively 5,12.0,102 and 250 ug/g dry matter in young leaves of tomato.