تاثير سطوح عناصر پتاسيم ، روي و مس بر عملكرد و كيفيت پياز در شرايط شور در دو منطقه عمده توليد پياز استان آذربايجان شرقي

The effect of various rates of potassium, zinc and copper on the yield and quality of onion under saline conditions in two majoronion growing regions of east Azarbayjan

Nutrient requirements by plants are different under saline and normal soil conditions. A completely randomized factorial block experiment with 27 treatments and 3 replications was carried out during 2000-2001 growing seasons in Bonab and Khosroshahr regions of East Azarbayjan to determined the effects of rates of potassium, zinc and copper on the yield and quality of Azarshahr red onions (Allurn cepa L.) under saline soil conditions. Each nutrient was applied at three rates, namely, 1- based on soil tests (200 kg potassium sulfate, 40 kg zinc sulfate, and 20 kg copper sulfate); 2- One and a half times the soil test levels (300 kg potassium sulfate, 60 kg zinc sulfate, and 30 kg copper sulfate); and 3- twice the recommended soil test levels (400 kg potassium sulfate, 80 kg zinc sulfate and 40 kg copper levels were at deficient concentrations at both locations and medium salinity conditions were detected. The results showed that potassium and zinc significantly affected the onion yields (a=0.01), TSS contents, as well as tbe nitrate concentrations of the onion bulbs at Bonab region. The maximum shelf life was obtained with the use of potassium, zinc and copper at twice the soil test requirements. Similarly the best tissue hardness of 1.62 kg/cm: was obtained with the application of 400 kg potassium sulfate/ha. The effects of potassium, zinc and copper treatments on the onions protein contents were statistically significant at 1% levels. The higbest protein content was obtained with the application the Ki,Zn and Cu at rates twice the soil test requirements. The highest level of vitamin C was measured with combined rates of 400 kg potassium sulfate, 80 kg zinc sulfate and 40 kg/ha of copper sulfate. The highest pH level and sugar concentration in the onion juice was obtained with 400 kg potassium sulfate per hectare. The results at Khosrowsbabr where the soil salinity level was higher than that of Bonab were about the same as described for Bonab experiments. However, the yields at Khosrowshahr were lower due to bigher soil salinity levels.