|
چکیده
|
Avena ludoviciana, is a dominant weed species in winter cereal crop mostly in wheat in Iran. It is a continuous problem due to mon-cropping, consistent cropping system and lack of efficient control measure. Soil disturbance regimes may affect seedling emergence of weed species in the cultivation. Therefore, the aims of this study was to test the effect of soil disturbances on seedling emergence of A. ludoviciana. Three populations (2 from west of Iran and 1 from northern part of the country) were collected in wheat fields in late spring 2016. The treatments were sowing seeds at soil surface, simulating zero tillage; sowing seeds at the depths of 0 to 5 cm and 0 to 15 cm simulating reduced and conventional tillage, respectively. 100 seeds were sown per pot, with four replications. Sowing was performed in 25 cm diameter pots in November 2016. The pots were buried in the soil outdoors. Samplings were done every 2 days by destructive counts, from late autumn to early winter 2016. Seedling emergence mainly took place in end of December 2016 to early January 2017. Statistical analysis showed a significant difference among populations and soil disturbance regimes in total seedling emergences. Total seedling emergence was between 1.8 to 5.8 % in all populations for seeds buried at soil surface. It was between 9.3 to 26 % for seeds buried at the depth of 0 to 5 cm and between 1.8 to 11.8 % for seeds buried at the depth of 0 to 15 cm. Therefore, seedling emergence was low for seeds buried at the soil surface, it increased for seeds buried at the depth of 0 to 5 cm followed by a decrease for seeds buried at the depth of 0 to 15 cm. It is concluded that zero tillage may result in reduced number of emerged seedlings in compare to reduced tillage in A. ludoviciana. Deeper burial of seeds may also result in reduced numbers of emerged seedlings. However, burial of seeds in deeper layers of soils by heaver soil disturbance may lead to building of long term soil seedbank in addition to accelerating loss of water from the soil. Thus, it may not be a beneficial operation to adapt consistently. Reduced tillage may be only considered for stimulating larger numbers of seedlings to emerge and reduction of soil seedbank. Comparatively, zero tillage could be a beneficial operation to adapt due to reduction of numbers of emerged seedlings, in addition to exposure of seeds to possible predation and conservation of soil moisture.
|