The effect of superabsorbent and integrated management of chemical and organic fertilizers on reducing boron toxicity in sure orange rootstock (Citrus aurantium)

The southern region of Kerman province with the production of citrus about 500 thousand tons per year, is ranked third in the country. One of the limiting factors of citrus production in this region in terms of quantity and quality is the concentration of some elements, especially boron in irrigation water. The effect of organic fertilizer, superabsorbent and chemical fertilizer with calcium on reducing the boron toxicity of irrigation water on sure orange rootstock in a factorial experiment was conducted in a randomized complete block design with 4 replications in 1996 and 1997. The factors include cow manure at two levels (0 and 2wt%), superabsorbent with three levels (0, 0.1 and 0.25wt%) and chemical fertilizers at three-level (control, balanced application chemical fertilizers without calcium based on soil test and balanced application of chemical fertilizers with calcium from calcium nitrate source based on soil test). The irrigation was done by drip irrigation with water with EC 845 μs / cm and boron concentration of 1.55 mg / l. The results showed that the simple and combined effects of superabsorbent, chemical and organic fertilizers on the percentage of leaves with boron toxicity symptoms, boron concentration was significant at the level of one percent. The highest concentration of boron per leaf (144.3 mg / kg) was observed in the control treatment with the highest number of leaves with symptoms of boron toxicity (22.97%) and the lowest concentration of potassium, magnesium, iron and zinc. Combined use of 2% organic matter + 0.25% superabsorbent + balanced use of chemical fertilizers based on soil test (without calcium) had the lowest percentage of leaves with symptoms of boron toxicity and the lowest amount of boron, but the highest percentage of magnesium increase (136.4) Showed potassium (197.4), iron (139) and zinc (123) compared to the control treatment. The results showed that separate and combined application of chemical and organic fertilizers with superabsorbent in soils with boron toxicity can reduce the effects of toxicity and improve plant nutritional conditions.