Effect of variety, fertilization and mixture sowing on oat biomass allocation in the alpine cultivated pasture

ObjectivesThis study focused on the response of biomass allocation of oat artificial grassland in alpine region to oat variety, fertilization and common vetch mixture level for providing a theoretical basis to establish the artificial grassland.

MethodsAccording to the orthogonal design of three factors (variety, fertilization and legume mixture) and four levels, there were four oat varieties, namelyAvena sativa L. cv. Qingyan No.1,A. sativa L. cv. Lena,A. sativa L. cv. Qinghai 444 andA. sativa L. cv. Qinghai, four fertilization measures, including without applying any fertilizers (CK₀), 75 kg/hm² urea + 150 kg/hm² NH₄H₂PO₄(NP), 1500 kg/hm² organic manure (OM) and 37.5 kg/hm² urea + 75 kg/hm² NH₄H₂PO₄ + 750 kg/hm² organic manure (NP + OM), and four common vetch mixture levels with 0 kg/hm², 45 kg/hm², 60 kg/hm²and 75 kg/hm². Different organ biomass of oats and common vetch were measured at the jointing, heading, flowering and milk stages of oats respectively.

ResultsThe aboveground biomass allocation of the oat artificial grassland was the highest under the fertilization of 37.5 kg/hm² urea + 75 kg/hm² NH₄H₂PO₃ + 750 kg/hm² organic manure (NP + OM) (84.91%) with theA. sativa cv. Qingyan No.1 (85.57%) without common vetch mixing (85.81%), while the underground biomass allocation was the highest under the common vetch mixture level 30 kg/hm² (16.29%) with theA. sativa cv. Lena (18.04%) without fertilization (16.02%). The ranges of the biomass allocation rates of stems, leaves, ears and roots were 44%–48%, 19%–24%, 17%–22% and 14%–18% respectively. The biomass allocation rates were changed with the growth stages: increasing, decreasing at the beginning and increasing later, increasing, and decreasing for stem, leaf, ear and root respectively. Under the influence of various factors, it was the oat’s leaves that played a dominant role in the early growing period, and the stems took place in the mid-late period. The common vetch’s root biomass, on the contrary, was leading at the beginning and its leaves took place in the mid-late period. Obviously, the biomass allocation of the oats played a significant role in the whole growing process. Meanwhile, there was a relationship defined as the allometric growth relationship, in other words, the aboveground biomass was always higher than the underground biomass in the whole growth period. The stem and root biomass allocation at the early and late growth stages were affected by the fertilization and variety separately, while the level of mixed sowing in the whole growth period affected the leaf growth, and the fertilization and the mixture level mainly influenced the ear biomass allocation.

Conclusions It was variety, fertilization and the common vetch mixture level that significantly affected the biomass allocation in the alpine region. The highest aboveground biomass allocation was under the fertilization of 37.5 kg/hm² urea + 75 kg/hm² NH₄H₂PO₃ + 750 kg/hm² organic manure with theA. sativa cv. Qingyan No.1 without common vetch, and the highest belowground biomass allocation was the treatment without fertilization with theA. sativa L. cv. Lena mixed with common vetch of 30 kg/hm².