Abstract:

Common vetch （Vicia sativa）is one of the most important fertilizer and forage dual-purpose green manure crops in China. Pre-cropping common vetch with wheat （Triticum aestivum） is a significant combination of agriculture and animal husbandry in Qinghai， Northwest China. The nitrogen （N）， phosphorus （P）， and potassium （K） accumulation and aboveground biomass of 47 cultivars （lines） and soil available nutrients were analyzed at the branching and initial flowering stage under field conditions in Qinghai. Principal component and cluster analyses were used to evaluate the crop N， P and K absorption capacity in order to identify cultivars suitable for use in Qinghai. The ranges of values for fresh herbage yield， and total N， P and K accumulation were 21.33-47.31 t·ha^-1， 100.34-212.51 kg·ha^-1， 10.31-25.25 kg·ha^-1 and 63.89-140.41 kg·ha^-1， respectively， for the 47 common vetch cultivars at the initial flowering stage. The cultivar ‘Hungary’ had the highest fresh grass yield and N and K accumulation capacity. The performance of ‘Hungary’ for those traits exceeded that of the local main cultivar， ‘Ximu 333’， by 58.92%， 44.78%， and 54.40%， respectively. Cultivar ‘7501’ had the highest P accumulation capacity， which was 27.78% higher than ‘Ximu 333’. Principal component analysis showed that the top five ranking cultivars were ‘Hungary’， ‘Grassland 79-1’， ‘Qingshui River （Linen）’， ‘324’ and ‘Black 741 common vetch’. ‘Hungary’ had the highest score （6.84）， and ‘751’ had the lowest score （-3.87）. Cluster analysis showed that the absorption capacity of N， P and K differed among cultivars and clustered into three groups in each case. For N， the groups with higher， medium and lower N absorption capacity contained， respectively， 4， 33 and 10 cultivars. For P， the groups with higher， medium and lower absorption capacity contained， respectively 7， 28 and 12 cultivars. For K， the groups with higher， medium and lower absorption capacity contained， respectively 8， 37 and 2 cultivars. For the cultivar groups with higher N， P and K absorption capacity contained respectively four， seven and eight cultivars as noted above， and the average N， P and K absorption was， respectively， 200.62 kg·ha^-1， 23.10 kg·ha^-1 and 115.23 kg·ha^-1. Planting common vetch significantly decreased soil inorganic N， available P and K levels at branching and initial flowering growth stages. Overall， among the top-five-ranked cultivars of the principal component analysis noted above， ‘Hungary’， ‘Grassland 79-1’， ‘Qingshui River （Linen）’ and ‘324’ showed the highest N and K absorption capacities， and ‘Grassland 79-1’ and ‘Hungary’ showed the highest P and K absorption capacities. These cultivars are therefore proposed as candidate cultivars for further field evaluation in Qinghai.

Key words: common vetch, nutrient absorption capacity, principal component analysis, cluster analysis