| In order to clarify the effects of post sowing soil compaction and pre winter irrigation on soil conditions and growth and development of winter wheat, a field experiment was carried out during 2012-2013 growing year at Gaobeidian, Hebei province, using two wheat cultivars, Shimai 12 and Shixin 828. The experiments for the two cultivars were designed as split plot arrangement, with irrigation as main plots (with and without pre winter irrigation, respectively), and soil compaction as split plots (with and without soil compaction after sowing, respectively). The data from the two cultivars had similar tendency, so that the averages of the two cultivars were used in the paper. The results showed that, the soil water contents during winter and spring were higher, and the soil temperature was more stable under the treatment with pre winter irrigation than that without pre winter irrigation. Compared with no soil compaction, the soil water contents during pre winter period and at double ridge stage increased, and the pre winter soil temperature was higher at night. The number of culms, LAI, dry matter accumulation amounts at all the growth stages was lower, and the photosynthetic rate of leaves at anthesis and chlorophyll SPAD at late grain filling was significant lower, the numbers of total spikelets, fertile spikelets, grains per spike and grain yield tended to decrease under the treatment with pre winter irrigation than that without pre winter irrigation. The pre anthesis dry matter accumulation of the treatment with compaction was lower. But the dry matter accumulation amounts were not significantly different between those with and without compaction at maturity, because the photosynthetic rate and chlorophyll SPAD of leaves of the treatment with compaction decreased slowly after anthesis, so that more dry matters were accumulated after anthesis. The spikes per hectare with compaction was less than that without compaction, but the grain yield difference between the treatments with compaction and without compaction was not significant, because more grains per spike and the higher 1 000 grain weight was obtained in the treatment with compaction. According to the results of the study, pre winter irrigation is an effective measure to protect wheat seedlings from freezing injury, but in terms of improving yield and water use efficiency, it is not needed under the conditions of sufficient soil moisture after sowing. Under such conditions, post sowing soil compaction should be applied to alleviate the adverse effect of low temperature and temperature fluctuation on winter wheat. |
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