Effects Of Magnesium, Iron, Boron Deficiency On The Growth And Nutrition Absorption Of Major Citrus Rootstocks

In our country, the citrus-growing regions are mostly located in the mountainous where have poor conditions of soil and geography. In recent years, the nutrient is difficult to absorb because of the discomfort soil pH value and the serious nutrient loss, the visible symptoms of nutrient deficiency in citrus trees became increasingly serious. Deficiency of magnesium, iron and boron are very common and prominent in many nutrient deficiency symptoms that has became an important question to be solved. This study is according to the actual problem and need of production, five citrus rootstock seedlings were as experimental materials in hydroponic culture, compared the effect of plant growth, photosynthetic characteristics and the difference of nutritional absorption on citrus rootstocks in magnesium, iron and boron deficiency. Find out the resistant rootstock in five citrus varieties at last. The results indicated that:(1) Magnesium deficiency on each rootstockThe lower leaves showed different levels of leaf chlorosis and part of the leaf venation in magnesium deficiency. It represent that Red tangerine has high photosynthetic capacity and high resistance in plant high, total leaves, leaf area, chlorophyll content, net photosynthetic rate, total root length, number of tips, total root surface, Carrizo citrange has less resistance than Red tangerine, but more resistance than Trifoliate, Fragrant citrus and Chongyi Wildmandarin; Red tangerine plant has higher resistance capacity of dry matter accumulation, relative growth rate and magnesium specific absorption rate than other citrus rootstocks, Carrizo citrange and Chongyi Wildmandarin followed by Red tangerine, Trifoliate, Fragrant citrus are more sensitive than others.(2) Iron deficiency on each rootstockIn the middle and later periods of iron deficiency treatment, the most evident effect is mesophyll chlorosis. Fragrant citrus in plant high, total leaves, leaf area, number of tips, total root volume and total root surface have shown a strong resistance in Fe deficiency. Furthermore, Fragrant citrus showed high growth and absorption capacity in relative growth rate and iron specific absorption rate than other four rootstocks. Except Fragrant citrus, Red tangerine is second only to Fragrant, but more resistant than Trifoliate, Carrizo citrange and Chongyi Wildmandarin.(3) Boron deficiency on each rootstockAfter boron deficiency treatment, leaf showed the symptoms of chlorosis, vein cork and finally burst. The root of Red tangerine showed high absorption capacity and Brorn deficiency resistance in the number of tips, total root surface, total root volume, the shoot of Chongyi Wildmandarin showed high resistance in total leaves, leaf area, the dry weight of shoot and rate of relative growth. Carrizo citrange, Fragrant citrus and Trifoliate are more sensitive than other rootstocks.