其他摘要 | 【Objectives】The application of nitrogen fertilizer is one of the key measures to increase seed yield
of Gramineous forage. In this study, a field experiment was conducted in artificial Leymus chinensis (Trin.) Tzvel
grassland to understand the effects of nitrogen fertilizer on seed yield and its components, and to providetheoretical and practical basis for management of artificial Leymus chinensis (Trin.) Tzvel grassland.
【Methods】The experiment was conducted from 2013 to 2015 with Leymus chinensis (Trin.) Tzvel ‘Zhongke
No.2’ as materials. The experiment included five nitrogen level treatments (N 0, 60, 120, 180, 240 kg/hm2) with
three randomized blocks. In each treatment, half of N fertilizer was applied at green stage (late March) and half at
harvest stage (late July). Seed yield and yield components were measured at harvest stage. 【Results】The
experimental years and N fertilizer had significant effects on seed yield. The yield increased gradually with
experimental years. However, the seed yield was initially increased and then decreased in 2013 and 2014. In 2013,
the optimal N rate was 104.9 kg/hm2 with a highest seed yield of 395.2 kg/hm2, but the yield was not significantly
affected by N fertilizers. In 2014, the optimal N rate was 173.5 kg/hm2 with a highest seed yield of 857.8 kg/hm2,
which was 56% higher than control treatment. In 2015, seed yield increased with N rate, with the highest yield of
1865 kg/hm2 at N rate of 180 kg/hm2, which was 206.6% higher than control treatment. The results of path
analysis indicated that seed yield was significantly correlated with spike number (r = 0.883, P < 0.01). Spike
number had largest direct path coefficient to seed yield (0.717) among all the variables, while tiller number had
the highest indirect effect on seed yield through spike number, indicating that spike number contributes most to
seed yield. Spike number was not affected by N treatmetn in 2013, but had similar responding pattern to N
treatment to seed yiled in 2014 and 2015. The spike number increased significantly in 2014 and 2015 by
consecutive application of N fertilizer among the three years. Furthermore, the application of N fertilizer
significantly increased spike length, florets/spikelet, grain number/spike and seed setting rate, but did not affected
1000-seed weight and spikelet/spike. 【Conclusions】The optimal amount of N fertilizer for seed yield was
104.9–180.0 kg/hm2 and increased with planting year increasing (104.9 kg/hm2 in 2013 and 180.0 kg/hm2 in 2014
and 2015). The spike number was the key factor influencing yield, which was not affected by N fertilizer
application of current year, but was influenced by the precipitation from August to October and the amount of N
fertilizer after mature stage in the previous year. The negative direct coefficient for spike number to spike length,
1000-seed weight and florets/spikelet could be offset by adding N fertilizer. |
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