Estimation models of leaf biomass and nutrient content for Caragana korshinskii in Kubuqi Sandy Land of northern China

ObjectiveCaragana korshinskii is a kind of leguminous plant with rapid growth, exuberant foliage, strong wind and sand fixing ability. Meanwhile, the crude protein (CP) content of stem and leaf is relatively high and it has a wide range of forage development prospects. However, the leaf biomass and nutrient contents of caragana are different at various stages of development and its forage ability is limited. Therefore, in order to break the limitations of the use of caragana leaves, we should understand the changes of leaf biomass and nutrient content during the growth stages of caragana.

MethodThe study used caragana as research material in Kubuqi Sandy Land of northern China. Meanwhile, we measured leaf biomass and nutrient contents of caragana at different growth years and varied developing stages. In addition, we constructed the dynamic models of leaf biomass of caragana at different growth years, the estimation model of growth parameter and leaf biomass and the dynamic model of leaf nutrient contents.

Result(1) For different growth years, the leaf biomass of caragana increased first and then decreased within the year. The leaf biomass of 2, 3 and 5 years old caragana reached the peak value in July and the leaf content was 0.14, 0.32, 1.40 kg per plant, respectively, the determining coefficient of the growth fitting curve was greater than 0.8, and the results of F test all reached a significant level (P < 0.05). (2) The CP content of caragana leaves was all over 16.0% during different growth years, and the overall change showed a downward trend during the year (the determining coefficient of the fitting curve was greater than 0.8), and the highest CP contents appeared in May each year. (3) There were no significant changes in the contents of neutral detergent fibers and acidic detergent fibers in caragana at different growth years, and the change trend was different within the year.

ConclusionAccording to the results, it can be seen that July is the period when the biomass of caragana leaves reaches its maximum, and May is the period when the CP contents of caragana leaves reach its maximum value. Therefore, according to the comprehensive consideration of the growth period and nutrient value of caragana leaves, May and July are the main utilization periods.