Sowing

About: Sowing is a research topic. Over the lifetime, 33888 publications have been published within this topic receiving 273438 citations. The topic is also known as: seeding.

Agronomic evaluation of a tiller inhibition gene (tin) in wheat. I. Effect on yield, yield components, and grain protein

Abstract: Reduced tillering cereals have been proposed as being advantageous under terminal drought conditions through their reported reduction in non-productive tiller number and reduced soil water use prior to anthesis. This study was conducted to determine whether wheat (Triticum aestivum L.) lines containing the tiller inhibition (tin) gene have a yield penalty over their commercial near-isogenic counterparts. A terminal drought was experienced in all experiments. The effects of the tin gene were investigated in 4 different near-isogenic pairs of lines grown at 2 sowing densities at 4 locations in the eastern Australian wheatbelt over a 3-year period. Averaged over all experiments and lines, grain yield was unaffected by the presence of the tin gene. However, the highest yielding line contained the tin gene and its yield was 5% higher than all other lines. Averaged across the different genetic backgrounds, the tin gene decreased fertile spike number by 11%, increased the number of kernels/spike by 9%, and there was a 2% increase in kernel weight. The tin gene increased the harvest index by an average of 0.02, whereas above-ground biomass was reduced by 7%. Increasing sowing density from 50 to 100 kg/ha had little influence on yield or yield-related characteristics in both the restricted tillering and freely tillering lines. There was an interaction between sowing rate and the presence of the tin gene on yield, with tin lines yielding 0.2 t/ha more than the freely tillering lines at the higher sowing rate, whereas there was no effect at the lower sowing rate. The response of several lines containing the tin gene to nitrogen fertiliser was also investigated at 2 sites. Nitrogen increased spike number in all lines but the number remained around 20% less than in the freely tillering cultivars. The yield of wheat lines containing the tin gene was 6% greater than their near-isogenic pairs where nitrogen status was high in the presence of terminal drought. Grain protein concentration was unaffected by the presence of the tin gene at high grain protein sites, whereas at lower grain protein sites it had a positive effect.

Assessment of weed and crop fitness in cover crop residues for integrated weed management

Abstract: Cover crop residues are not widely used for weed control because, as a stand-alone tactic, they do not effectively suppress all weeds and their duration of weed control is too short. Field experiments were conducted in 1995 and 1996, under both irrigated and rainfed conditions, to quantify Amaranthus spp., Setaria spp., and soybean emergence and growth in residues of fall-planted, spring-killed barley, rye, triticale, wheat, and hairy vetch. For both weed species, seedling emergence was reduced 3 wk after soybean planting by rye and wheat residues (≥ 2, 170 kg ha−1) in 1996. In 1996, Amaranthus spp. canopy volume was reduced 38 to 71% by residues 3 wk after planting. Likewise, Setaria spp. canopy biomass was reduced 37 to 97% in residues 5 wk after planting over both years. The response comparison index was used to identify frequency by which weed growth was placed at a disadvantage relative to soybean growth. Amaranthus spp. and Setaria spp. growth suppressions 3 to 5 wk after planting indicate potential times for intervention with other integrated weed management tactics such as reduced postemergence herbicide rates and interrow cultivation.

Effect of waterlogging on the growth, grain and straw yield of wheat, barley and oats

Abstract: Wheat, barley and oats were grown in undrained plastic buckets containing soil collected from upper, mid and lower slopes of a valley that was subject to winter waterlogging. Two weeks after planting, the water content for each soil was either maintained at 80 per cent of full water holding capacity or subjected to intermittent or continuous waterlogging for six weeks. In a second experiment, using lowerslope soil only, the same three cereals were subjected to similar waterlogging treatments commencing at two or six weeks after planting or at ear emergence. In this experiment the plants received either no nitrogen fertilizer or 100 kg nitrogen ha-1. Both soil composition and waterlogging had a significant effect on plant yield but the effect of waterlogging was much greater. Waterlogging reduced root growth and penetration, the production of tillers and fertile heads, and delayed ear emergence and plant maturation. Reduction in plant growth rate was measurable within three days from the onset of waterlogging. In the first experiment intermittent and continuous waterlogging reduced vegetative growth yield (mean of three cereals in three soils) by 37 per cent and 55 per cent respectively; and wheat grain yields by 40 per cent and 53 per cent respectively. However, there was no differential effect of the two waterlogging treatments on the grain yield of barley and oats, the mean reduction being 39 per cent for barley and 48 per cent for oats. In the second experiment waterlogging at the earliest growth stage resulted in the greatest reduction in root, herbage and grain yield. Waterlogging at ear emergence killed some tillers and roots and reduced the plants stability at maturity. Grain size was reduced in some treatments. Application of nitrogen fertilizer compensated, either partially or fully, for reduction in grain yield due to waterlogging treatments on all three cereals. Some reasons for yield reduction in the three species and the practical implications of the results are discussed.

Presence of the a.i. imidacloprid on vegetation near corn fields sown with Gaucho ® dressed seeds

Abstract: In recent years the widespread use of corn seed hybrids dressed with the systemic insecticide Gaucho ® (a.i. imidacloprid), has been frequently linked, by beekeepers with bee colony losses registered during the corn sowing season. On the basis of a preliminary experiment, where the loss of imidacloprid from the pneumatic seed drills was highlighted, the aim of the study was to verify both the amount of contamination and the persistence of the active ingredient on leaves and flowers of spontaneous plants growing near corn fields in which Gaucho ® dressed seeds had been used. The observations were carried out in north eastern Italy on five different commercial corn hybrid seeds, three dressed with Gaucho ® [hybrids 2 (H2), 4 (H4) and 5 (H5)], one with a new adjuvant (H5). The escape of the active ingredient from the fan drain of the pneumatic seed drill was monitored using paper filters, whereas samples of grass and flowers were collected from the borders of sown fields. Meteorological data were registered. The samples (paper filters, grass and flowers) were analyzed using a gas chromatography method. Paper filters on the output of the drill fan have shown, at different concentrations, an escape of imidacloprid from the fan for each kind of Gaucho ® dressed seed; the order of magnitude of the escape ranged on average for H2, H4 and H5 from 120 to 240 µg of imidacloprid for 1 g of paper filter at 240 seconds. Therefore the new adjuvant did not eliminate the loss of active ingredient. Even if at different concentrations for each kind of Gaucho ® dressed hybrid, imidacloprid was found the same day of sowing on spontaneous vegetation near the corn fields; H2 showed the highest level of residues with values of 123.7 and 58.2 ng/g of imidacloprid respectively on flowers and grass. Residual imidacloprid on grass and flowers was found at least four days after sowing (H2), while the washing effect of heavy rain has been observed, which seemed to hide the detection of the active ingredient (H4 and H5). The investigation showed that Gaucho ® dressed corn seeds during sowing operations can release imidacloprid into the environment, and therefore bees and wild pollinator insects could bee exposed to the insecticide molecule. Plants could accumulate the active ingredient released during different sowing operations in the same area and become polluted for a time depending on the length of the sowing period. The same problem could be extended to other pesticides, at present or in the future, used in seed dressing.