Effects of liquid organic fertilizer on the growth and nutrient absorption of young Newhall navel orange trees

【Objective】In order to provide technical support for the development and application of liquid organic fertilizer for irrigation of navel orange orchard in hilly areas, the effects of single application of animal and plant-based organic liquid fertilizer or combine with chemical fertilizer on growth and nutrient absorption of Newhall navel orange young trees was researched.【Method】Field experiment was carried out with two-year-old Newhall navel orange young trees and CK(100% chemical fertilizer nitrogen), T1(100% animal-based N), T2(100% plant-based nitrogen), T3(50% animal-based nitrogen+50% chemical fertilizer nitrogen) and T4(50% plant-based nitrogen+50% chemical fertilizer nitrogen) were set to measure the growth and nutrient absorption of Newhall navel orange trees under different treatments and principal component analysis was processed.【Result】Compared with CK, the biomass accumulation of Newhall navel orange saplings was promoted by applying organic liquid fertilizer from animal and plant sources alone or combined with chemical fertilizer(T1-T4 treatments). The dry weight and total dry weight of scion stem, rootstock stem, root system and whole plant of Newhall navel orange seedlings in T4 treatment were higher than those in other treatments, which significantly increased by 62.42%, 40.14%, 42.08% and 47.21% respectively compared with CK(P<0.05, the same below). For the growth of Newhall navel orange, T1-T4 mainly affected the basal diameter and chlorophyll relative content(SPAD value) of spring shoot leaves. Compared with CK, all treatments significantly promoted the increase of basal diameter, with the highest increase rate of 29.17%(T4 treatment). Except T2 treatment, other treatments significantly increased the SPAD value of spring shoot leaves, and T4 treatment had the most obvious effect, increase reached 9.19%. Except T3 treatment, other treatments significantly increased the spring shoot length and specific leaf weight of fruit trees, and T2 treatment was the most significant, increased by 36.67% and 12.10% respectively compared with CK. In addition, T4 treatment significantly increased the total root length and total root surface area of fruit trees, but significantly reduced the average root diameter by 18.42%. The absorption of nitrogen, phosphorus and potassium in different organs of young navel orange trees was affected by the application of organic liquid fertilizer alone or combined with chemical fertilizer(T1-T4 treatments). The results of principal component analysis showed that the order of comprehensive evaluation scores of growth and nutrient absorption of navel orange saplings under different fertilization treatments was T4>T1>T3>T2>CK.【Conclusion】The application of liquid organic fertilizer from animal and plant sources alone or combined with chemical fertilizer can promote the growth of Newhall navel orange young trees. The results of principal component analysis shows that 50% plant-based nitrogen+50% chemical fertilizer nitrogen(T4 treatment) has the best effect on the growth and nutrient absorption of navel orange young trees and it can be popularized and applied in the irrigation and application system of liquid organic fertilizer in young navel orange garden in southern of Jiangxi.