فهرست مطالب

Plant Production - Volume:12 Issue:3, 2018
  • Volume:12 Issue:3, 2018
  • 76 صفحه،
  • تاریخ انتشار: 1397/09/01
  • تعداد عناوین: 7
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  • Nitrogen Accumulation Characteristics of High-Yield Spring Maize in Northeast China
    Yuhui Geng, Guojun Cao, Shuhua Wang Pages 149-157

    Achieving a high yield is an ongoing major challenge to meet China’s increasing food demand. The N accumulation characteristics of high-yield spring maize are likely different from those of conventional-yield spring maize. A 2-year field experiment was conducted to investigating the N accumulation characteristics of high-yield (HY) (> 15 t ha−1) spring maize in comparison with spring maize of medium yield (MY) and low yield (LY). The maximum N stage accumulation appeared between stages V6 and V12. N stage accumulation of LY decreased rapidly after the V12 stage, while N stage accumulation of HY remained high until the R2 stage and was two times that of LY at the R2 stage. The percentage contribution of N stage accumulation to the total accumulation was lower for HY than for LY during the vegetative stages (VE to VT), but higher for HY than for LY during the reproductive stages (VT to R6). The N remobilization amount in different organs was higher for HY than for MY and LY. The total apparent contribution to grains of HY (58.1%) was lower than that of MY (60.2%) and LY (75.5%), suggesting that most of the final grain N of HY was directly derived from the root system supply during the reproductive stages. Overall, these results indicated that maintaining a sufficient N supply during the growing stages, especially the reproductive stages, can increase the amount of N uptake, delay leaf senescence and maintain high photosynthetic activity, leading to a high yield.

    Keywords: N uptake , Spring maize , Remobilized N, High yield, Northeast China
  • Soybean Yield Gap in the Areas of Yield Contest in Brazil
    Rafael Battisti, Paulo Cesar SentelhasEmail author, Jo?o Augusto Lopes Pascoalino, Henry Sako, Jo?o Paulo de S? Dantas, Milton Ferreira Moraes Pages 159-168

    Soybean yield is mainly influenced by the interaction among genotype, environmental conditions and management practices. Based on that, the aim of this study was to quantify the soybean yield gap caused by water deficit (YGWD) and sub-optimum crop management (YGCM), considering data from the areas of soybean yield contest in Brazil. Potential (Yp) and attainable (Ya) yields were estimated by a crop yield simulation model, whereas actual farmers yields (Yf) were obtained from the contests conducted by the Brazilian Soybean Strategic Committee (CESB), comprising 200 sites. The YGWD and YGCM were, respectively, calculated by the difference between Yp and Ya, and Ya and Yf. The climate efficiency (EFC) was obtained by the ratio between Ya and Yp, while crop management efficiency (EFM) considered the ratio between Yf and Ya. The mean Yf from CESB was 5021 kg ha−1, higher than the national average of about 3000 kg ha−1. The YGWD and YGCM were, respectively, 2931 and 3458 kg ha−1, representing 46 and 54% of total yield gap. The weather conditions did not affect Yf in the studied sites with lower EFM. For sites with EFC higher than 0.80, Yf increased in a rate of 92 kg ha−1 per percentage of increase in EFM. When comparing the national average and CESB winners, the results showed that average Yf could be increased in 2514 and 2584 kg ha−1, respectively, by closing YGCM and YGWD, which shows that there is room to double the present Brazilian soybean yield by adopting the technology already available to the farmers. These results can serve as reference to guide other studies about soybean yield gap around the world, helping policy makers and other stakeholders to elaborate strategies for closing yield gaps and making soybean production more sustainable.

    Keywords: Crop simulation model , Closing yield gap , Rainfed crop , Climat and management efficiencies
  • Adaptation and Productivity of Selected Grain Legumes in Contrasting Environments of Kwazulu-Natal, South Africa
    Tendai P. ChibarabadaEmail author, Albert T. Modi, Tafadzwanashe Mabhaudhi Pages 169-180

    Underutilised grain legumes are being promoted as part of crop diversification efforts. However, the lack of comparable information to major legumes is limiting these efforts. The first benchmarking study to compare development and productivity of selected underutilised [bambara groundnut (Vigna subterranea) and cowpea (Vigna inguiculata) and major [groundnut (Arachis hypogaea) and common bean (Phaseolus vulgaris)] grain legumes under varying environments was conducted in KwaZulu-Natal, South Africa during 2015/16 and 2016/17. A completely randomised block design with three replications was used at all sites. Crop phenology, yield, water use (ET) and water productivity (WP) were determined for the crops. Data were analysed separately using ANOVA. Biplot analysis was done using GGE. Bambara groundnut was slow to emerge across sites and seasons (> 211 degree days). Common bean was early maturing (< 1677 degree days) while groundnut and bambara groundnut were late maturing (> 1699 degree days). Yield varied significantly (P < 0.05) across environments and seasons. For all environments, common bean had the lowest ET (208–313 mm); bambara groundnut had the highest ET (437 mm), which was recorded during 2015/16. The highest and lowest WP (0.98 and 0.12 kg m−3, respectively) were observed for groundnut. Cowpea had the most stable WP (0.28–0.38 kg m−3). Based on mean values, the major legumes out-yielded the underutilised grain legumes. Crops behaved differently across different environments. The potential of bambara groundnut was limited to sandy soils. There is need for investments in improving yield of underutilised grain legumes to make them more attractive for crop diversification.

    Keywords: Bambara groundnut , Cowpea, Common bean , Evapotranspiration, Groundnut , Water productivity
  • Sowing Dates and Seeding Rates Affect Soybean Grain Composition
    Renan Caldas UmburanasEmail author, Anderson Hideo Yokoyama, Leonardo Balena, Gabriela Caroline Lenhani, Angela Moraes Teixeira, Roberta Let?cia Krüger, Klaus Reichardt, Jackson Kawakami Pages 181-189

    The effect of agronomic practices in soybean grain composition lacks information. In addition, the importance of protein and oil contents in soybean grains is increasing due to the industry demand for grain quality. It is well known that soybean grain weight can change according to environmental conditions, like different sowing dates, however, the consequences in grain composition need to be better understood. The aim of this study was to evaluate the composition, oil and protein yield of soybean grains, in response to different sowing dates (early, mid, and late), seeding rates (15, 25, 35, and 45 seeds m−2), and two growing seasons. Late sowing reduced grain oil content, soybean oil yield, and protein yield. The increase in seeding rate from 15 to 45 seeds m−2 increased grain protein content from 33.8% to 35.1%, oil yield increased 10% and protein yield, 17%. The results of this study show that in the management of soybean crops the sowing date and seeding rate can change grain composition. This information demonstrates that agronomic practices should be considered by growers and breeders when considering soybean grain quality.

    Keywords: Glycine max , Densities , Plant management , Sowing times , Lipid
  • Mathematical-Economic Analysis to Determine Optimal Applied Water in Case of Crop Price Depends on Its Quality
    Ali ShabaniEmail author, Ali Reza Sepaskhah, Mohamad Khorramian Pages 191-202

    In some crops, crop price is variable and dependent on yield quality e.g., price of sugar beet root. Therefore, all parameters that increase the sugar content, increase the unit sugar beet root price e.g., irrigation water and nitrogen application rate. In this study, the required equations were derived for determining optimum applied water for sugar beet at variable crop price as a function of sum of irrigation water and seasonal rainfall under land and water limiting conditions. Results showed that the optimum applied water depth under land limited resulted in 1.2% increase in net income per unit area compared to maximum yield condition. Whereas, under water limiting condition, the net benefit per unit water is maximized and increased by 12% compared to maximum yield conditions. Increase in base crop price resulted in decrease and increase in optimum water depth under water and land limiting conditions, respectively. Under water limiting conditions, increase in seasonal rainfall from 0 to 6 and 12 cm decreased the optimum applied water from 47.4 to 54.8 and 65.3% and increased the irrigated area from 90 to 135 and 225%, respectively, compared with the full irrigation conditions.

    Keywords: Irrigation water optimization , Sugar beet , Crop price , Rainfall
  • Effect of Irrigation Method on Adaptation Capacity of Rice to Climate Change in Subtropical India
    Yogesh Anand RajwadeEmail author, Dillip Kumar Swain, Kamlesh Narayan Tiwari Pages 203-217

    Water management technologies under projected climate change will play key role in sustainable rice production. Modeling approach was used to assess the impact of climate change on rice production under drip irrigation (DIR) and conventional puddle transplanted (PTR) in subtropical India. The genotype coefficients of CERES-Rice model (cv. Naveen) were determined and tested using experimental data for the years 2012–2014. Close match between the observed and simulated values was recorded during both the years which led to higher d-index (> 0.95) and lower normalized RMSE (RMSEn) values. Under the projected climate change scenarios (RCP 4.5 and RCP 8.5), grain yield reduced over the period 2020–2080, with higher decline in RCP 8.5. Over the period, higher nitrogen (N) use efficiency in DIR led to lower yield reduction over PTR. Among the different adaptation measures, higher fertilizer N dose was able to mitigate negative impact of temperature rise up to 3.3 °C over base period, beyond which grain yield was significantly reduced. Results of the simulations for the different sowing dates stated higher reduction in grain yield with delayed sowing in DIR as well as in PTR for both (RCP 4.5 and 8.5) climate change scenarios. However, early sowing resulted in better crop establishment in DIR leading to better yield compared to PTR in both the climate change scenarios.

    Keywords: Adaptation , Climate change , Drip irrigation , Rice yield
  • Modeling the Population Dynamics of a Community of Two Grass Weeds of Winter Wheat in a Mediterranean Area
    Jose L. Gonzalez, Andujar, Fernando Bastida Pages 219-223

    Compared to classical, only-one weed species models, demographic projections accounting for species interactions within the weed community might represent a more realistic approximation to the outcome of weed control options in Mediterranean cereal crops. A mathematical model for simulating the dynamics of a weed community composed of populations of Lolium rigidum and Avena sterilis growing in winter wheat under a Mediterranean climate has been constructed using previous reported data on demographic rates. The model was used to simulate the population long-term dynamics and the effect of eight herbicide-based control strategies. In absence of herbicide application, our model predicts that A. sterilis seed bank increases steadily up to an equilibrium density of 2567 seeds m−2 whereas L. rigidum is driven to extinction after a period of 9 years. The most effective strategy in terms of reducing weed abundance in the long-term was the application of full dose of herbicide controlling L. rigidum and half-dose of herbicide controlling A. sterilis, which resulted in an equilibrium level of 25 seeds m−2 for L. rigidum and extinction of A. sterilis. A sensitivity analysis showed that the demographic process to which the model was more sensitive was seed rain loss in both species. Furthermore, control tactics specifically focusing on these demographic parameters should be investigated.

    Keywords: Seed bank , Avena sterilis , Lolium rigidum , Herbicide , Simulation, Sensitivity analysis