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.

Effects of sowing time and nitrogen fertiliser on canola and wheat, and nitrogen fertiliser on Indian mustard. II. Nitrogen concentrations, N accumulation, and N fertiliser use efficiency

Abstract: Canola, Indian mustard, and wheat were grown at Ariah Park and Cowra (canola only) in the cropping belt of New South Wales, Australia, to determine the effects of sowing time (canola and wheat) and nitrogen (N) fertiliser on N concentrations and N accumulation in shoots, N fertiliser use-efficiency, and N removal in grain of the crops. Concentrations of N in shoots of all crops decreased during the season, irrespective of sowing time or N fertiliser rate. Late sowing decreased N accumulation by 55% and 40% for canola and wheat, respectively, at Ariah Park, and by 50% for canola at Cowra, but increased canola and wheat grain N (protein) concentrations more than the applied N. All crops accumulated most of their N before anthesis, and there was little N accumulation after the end of flowering; however, sowing canola late increased the proportion of N accumulated during flowering. Indices of N fertiliser use efficiency were reduced by sowing late, but N use efficiencies of the oilseeds at each sowing time were similar to values for wheat after accounting for differences in the biosynthetic costs of grain and straw production. Removal of N in canola grain from an April sowing was 35% greater than N removal by wheat grain sown at the same time, but was similar for both crops from late May and July sowings. Consequently, more N fertiliser should be applied to canola than wheat to obtain high grain yields when both crops are sown early in the season. It was concluded that sowing early was essential to achieve high N use efficiency, reduce potential losses of N, and maximise economic returns from N fertiliser.

Reduced growth and yield of wheat with conservation cropping. II. Soil biological factors limit growth under direct drilling

Abstract: Wheat was grown in intact cores of soil removed from a field experiment in which seedlings had grown more slowly in direct-drilled soil than in cultivated soil. Experiments were conducted in controlled environments to resolve (1) whether shallower sowing of direct-drilled crops caused slower growth, (2) whether the soil factors causing the slower growth were physical or biological and (3) if biological, whether Rhizoctonia solani was the major pathogen. The conditions of the experiments removed possible constraints of water and nutrient supply but otherwise simulated the environment of wheat seedlings in southern Australia. Shallower sowing led to faster emergence and increased seedling growth, but irrespective of sowing depth, direct-drilled plants grew more slowly than plants in cultivated soil. Shoot growth of direct-drilled plants was 25-65% less than that of cultivated plants. These growth reductions were largely overcome by sterilizing the soil with y radiation or by fumigation with methyl bromide, indicating that biological factors were primarily responsible. Rhizoctonia was implicated as the cause of the reduced shoot growth when infection was severe (>3 on a 0-5 scale). There was no correlation between infection severity and shoot growth at moderate levels (<3) and significant reductions in shoot growth occurred in the absence of Rhizoctonia. These reductions were evident on the first leaf suggesting a direct influence on shoot growth rather than one mediated through inadequate uptake of water or nutrients. Infection of the germinating seed by Pythium spp. or the effects of phytohormones produced by inhibitory bacteria on the roots are possible causes of reduced shoot growth of direct-drilled seedlings. The dominant role of biological factors in determining plant response to soil management indicates the need for further studies to identify the organisms responsible, to determine the mechanism by which they influence shoot growth, and the effect of management on their populations and activity.

Symbiotic N2 fixation in pea and field bean estimated by15N fertilizer dilution in field experiments with barley as a reference crop

Abstract: The total amount of nitrogen derived from symbiotic nitrogen fixation in two pea and one field bean cultivar, supplied with 50 kg N ha−1 at sowing (‘starter’-N), was estimated to 165, 136, and 186 kg N ha−1, respectively (three-year means). However, estimates varied considerably between the three years. At the full bloom/flat pod growth stage from 30 to 59 per cent of total N2 fixation had taken place. The proportion of total N derived from N2 fixation at maturity was higher in seeds than in vegetative plant parts and amounted to 59.5, 51.3 and 66.3 per cent of total above-ground plant N in the two pea cultivars and field bean, respectively (three-year means). The recovery of fertilizer N was 62.2, 70.2, 52.1, and 69.5 per cent in the two pea cultivars, field bean and barley, respectively. Growth analysis indicated that barley did not meet the claims for an ideal reference crop in the15N fertilizer dilution technique for estimating N2 fixation in pea and field bean. ‘Starter’-N neither increased the seed yield nor the N content of the grain legumes.

Multispecies forest plantations outyield monocultures across a broad range of conditions

Abstract: Multispecies tree planting has long been applied in forestry and landscape restoration in the hope of providing better timber production and ecosystem services; however, a systematic assessment of its effectiveness is lacking. We compiled a global dataset of matched single-species and multispecies plantations to evaluate the impact of multispecies planting on stand growth. Average tree height, diameter at breast height, and aboveground biomass were 5.4, 6.8, and 25.5% higher, respectively, in multispecies stands compared with single-species stands. These positive effects were mainly the result of interspecific complementarity and were modulated by differences in leaf morphology and leaf life span, stand age, planting density, and temperature. Our results have implications for designing afforestation and reforestation strategies and bridging experimental studies of biodiversity–ecosystem functioning relationships with real-world practices. Description Diversity boosts plantation biomass Across experimental and natural systems, more diverse plant communities often have higher primary productivity. This effect can be due to complementarity between different species, which can more effectively use resources together, or a higher likelihood of more productive species being present. Feng et al. used data from 255 sites to test whether forest plantations with multiple species have greater productivity than monocultures (see the Perspective by Gurevitch). They found that multispecies plantings, on average, have taller and thicker trees and greater aboveground biomass accumulation than monocultures. This effect was mainly due to complementary between species, with greatest benefits from pairing species with different traits. —BEL Mixtures of tree species tend to grow better timber than monocultures, especially when species have complementary traits.

Growing Zostera marina (eelgrass) from Seeds in Land-Based Culture Systems for Use in Restoration Projects

Abstract: The use of aquaculture systems to grow the seagrass Zostera marina (eelgrass) from seeds for restoration projects was evaluated through laboratory and mesocosm studies. Along the mid-Atlantic coast of North America Z. marina seeds are shed from late spring through early summer, but seeds typically do not begin to germinate until the late fall. Fall is the optimal season to plant both seeds and shoots in this region. We conducted studies to determine if Z. marina seeds can be induced to germinate in the summer and seedlings grown in mesocosms to a size sufficiently large enough for out-planting in the fall. Seeds in soil-less culture germinated in the summer when held at 14°C, with percent germination increasing with lower salinities. Cold storage (4°C) of seeds prior to planting in sediments enhanced germination and seedling survival. Growth rates of seedlings were significantly higher in nutrient enriched estuarine sediments. Results from preliminary studies were used in designing a large-scale culture project in which 15,000 shoots were grown and out-planted into the Potomac River estuary in the Chesapeake Bay and compared with an equal number of transplanted shoots. These studies demonstrate that growing Z. marina from seeds is an alternative approach to harvesting plants from donor beds when vegetative shoots are required for restoration projects.