Capability evaluation of 50 hairy vetch cultivars (lines) as autumn green manure in Qinghai Province, Northwest China

Objectives Hairy vetch (Vicia villosa Roth.) is one of China’s most important fertilizer and forage dual-purpose green manure crops. The nitrogen (N), phosphorus (P), and potassium (K) accumulation and aboveground biomass of different hairy vetch cultivars (lines) were investigated to select those suitable for green manure cultivation in the Qinghai area.

Methods The N, P, and K accumulation and aboveground biomass of 50 cultivars (lines) and soil nutrients were analyzed under field conditions at the branching and initial flowering stages. Hairy vetch’s N, P, and K absorption capacity were evaluated using principal component and cluster analysis.

Results The range of values recorded for fresh grass yield, N, P, and K accumulation was 18.35–46.94 t/hm², 101.51–278.98 kg/hm², 10.39–29.80 kg/hm², and 59.33–157.54 kg/hm², respectively, for hairy vetch cultivars at the initial flowering stage. Cultivar ‘Maojiayeshaozi ’ had the highest fresh yield and ‘78-14’ had the highest N, P, and K accumulation capacity. The yield and N, P, and K accumulation in ‘Maojiayeshaozi ’ exceed the main local ‘Qingshao 1’ by 61.47%, 92.81%, 67.51%, and 86.50%, respectively. Principal component analysis showed that the top five cultivars were ‘78-14’, ‘Shaotengxuan’, ‘Maojiayeshaozi’, ‘Shandongzaoshushao’, and ‘78-171 shaozi’. Moreover, ‘78-14’ had the highest score (4.85) while ‘Soviet Union shaozi’ had the lowest score (−5.06). Cluster analysis showed that the absorption capacity of N, P, and K clustered into four groups in each case. For N, the high, higher, medium, and general absorption capacities were recorded for 1 cultivar, 12 cultivars, 15 cultivars, and 22 cultivars. For P, the high, higher, medium, and general absorption capacities were observed for 4 cultivars, 24 cultivars, 6 cultivars, and 16 cultivars. For K, the high, higher, medium, and general absorption capacities were recorded for 4 cultivars, 12 cultivars, 19 cultivars, and 15 cultivars. The group with high N, P, and K absorption capacities recorded 278.98, 27.94, and 145.91 kg/hm², respectively. Compared with pre-sowing, planting hairy vetch decreased inorganic N, available P and K contents at the branching and initial flowering stages, enhancing nutrient utilization in the fallow season.

Conclusions The biomass and nutrient absorption capacity of different hairy vetch cultivars (lines) in Qinghai are different. Overall, ‘78-14’ showed higher N, P, and K absorption capacity, and ‘Shaotengxuan’ and ‘Maojiayeshaozi’ shows higher P and K absorption capacity. Therefore, these cultivars are proposed as potential candidate cultivars for further field evaluation in Qinghai.