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.

How to model the effects of farming practices on weed emergence

Abstract: Summary Early weed emergence models directly relate the weed seedbank to emerged seedlings, with constant emergence rates for each tillage tool. These models compare cropping systems at long term in a given region. Other models relate emergence to rain and air temperature. They are useful in no-till systems with seeds close to soil surface. Recently, other authors split emergence into germination and pre-emergence growth, depending on soil climate. But seed survival and dormancy as well as tillage were not yet integrated. Models advising farmers for strategic farming decisions in a large range of situations must split emergence into mechanistic relationships distinguishing the various underlying biological subprocesses in order to correctly quantify the effect of cropping system. The model AlomySys for Alopecurus myosuroides emergence follows this principle, based on submodels predicting (a) soil environment resulting from the cropping system, (b) vertical soil seed distribution after tillage, and (c) seed survival, germination and pre-emergence growth depending on soil environment, seed depth, characteristics and past history. This model can be used to determine the optimal tillage modes and sowing dates, depending on the preceding crop succession, the following crop and the work constraints of the farmer.

Faba bean (Vicia faba L.) response to tillage and soil residual nitrogen in a continuous rotation with wheat (Triticum aestivum L.) under rainfed Mediterranean conditions

Abstract: The present field study was undertaken to determine the effects of tillage systems on faba bean (Vicia faba L.) yield over 11 yr and the effects of tillage systems and residual N on faba bean yield, yield components, and N uptake over 4 yr in a wheat (Triticum aestivum L.)-faba bean rotation under rainfed Mediterranean conditions. Tillage treatments included no-tillage and conventional tillage. Nitrogen fertilizer rates were 0, 50, 100, and 150 kg N ha -1 , applied only to wheat. The weather had a marked influence on seed yield, which ranged from 587 to 2964 kg ha -1 . Thousand-seed weight rose with increasing seed yield and seeds per pod, seeds per pod decreased with increasing pods per square meter, and harvest index rose with increasing seeds per pod but decreased with rising pods per square meter. Over the 11-yr study period, the tillage system did not significantly influence seed yield. However, in three rainy years, conventional tillage was more productive than no-tillage. Seed yield, total dry matter, and N uptake were lower at 0 kg N ha -1 , and no significant differences were recorded among other N rates. Total N uptake ranged from 50 to 127 kg N ha -1 while seed N uptake fluctuated between 34 and 107 kg N ha -1 . Soil nitrate at wheat sowing after faba bean was not affected by the type of tillage system used while the effect of the N rates applied to wheat 2 yr before was very reduced due to N fixed by the faba bean crop.

Effect of weed management and seed rate on crop growth under direct dry seeded rice systems in Bangladesh.

Abstract: Weeds are a major constraint to the success of dry-seeded rice (DSR). The main means of managing these in a DSR system is through chemical weed control using herbicides. However, the use of herbicides alone may not be sustainable in the long term. Approaches that aim for high crop competitiveness therefore need to be exploited. One such approach is the use of high rice seeding rates. Experiments were conducted in the aman (wet) seasons of 2012 and 2013 in Bangladesh to evaluate the effect of weed infestation level (partially-weedy and weed-free) and rice seeding rate (20, 40, 60, 80, and 100 kg ha−1) on weed and crop growth in DSR. Under weed-free conditions, higher crop yields (5.1 and 5.2 t ha−1 in the 2012 and 2013 seasons, respectively) were obtained at the seeding rate of 40 kg ha−1 and thereafter, yield decreased slightly beyond 40 kg seed ha−1. Under partially-weedy conditions, yield increased by 30 to 33% (2.0–2.2 and 2.9–3.2 t ha−1 in the 2012 and 2013 seasons, respectively) with increase in seeding rate from 20 to 100 kg ha−1. In the partially-weedy plots, weed biomass decreased by 41–60% and 54–56% at 35 days after sowing and at crop anthesis, respectively, when seeding rate increased from 20 to 100 kg ha−1. Results from our study suggest that increasing seeding rates in DSR can suppress weed growth and reduce grain yield losses from weed competition.

Quantification of allelopathic potential of sorghum residues by novel indexing of richards' function fitted to cumulative cress seed germination curves.

Abstract: The inhibitory activity of aqueous extracts of field-grown sorghum (Sorghum bicolor cv. Bird-a-boo) herbage and roots was quantitatively indexed by three aspects of cumulative cress (Lepidium sativum cv. Curlycress) seed germination: the germination onset; weighted mean rate; and final germination percentage. Extract potency was greatest for herbage collected four weeks after planting but declined sharply thereafter as the plants matured. About 91% of the inhibitory activity obtained from four-week-old herbage was in a low molecular weight fraction. Differential effects of herbage and root extracts on cress seed germination suggest that the nature and/or proportion of biologically active substances extractable from these plant parts is dissimilar.

A comparison of different chemicals for osmotic treatment of vegetable seed

Abstract: SUMMARY Samples of carrot, celery, leek and onion seed were treated before sowing by imbibition in osmotic solutions of polyethylene glycol 6000 (PEG), glycerol and potassium dihydrogen orthophosphate (KH2PO4). The solutions were sufficiently concentrated to prevent germination during treatment, and within each species, the amount of water taken up by the seeds during treatment did not vary greatly between solutions. All treatments increased the rates of seed germination and seedling emergence compared to untreated controls, but glycerol-treated seeds germinated and emerged significantly more slowly than did PEG- and KH2PO4-treated seeds. The effects of PEG and glycerol treatments on percentage germination and seedling emergence were small, but KH2PO4 treatment tended to reduce percentage germination and emergence, most markedly in leek and one cultivar of celery. It is concluded that PEG treatment gives the most consistently beneficial effects for the range of species tested.