Information of crop phenological stages is essential for evaluating crop productivity and crop management. We used MODIS EVI time-series to monitoring winter-wheat phenology in North China. The phenological estimations from MODIS EVI measurements were compared with situ data. Results indicate that winter-wheat phenological stages derived from MODIS EVI time series data is feasible. The spatial pattern of winter-wheat shows obvious latitudinal trends in this region. Green up, tassel, and maturity onset dates in more southern zone begin earlier progressively than the northern zone.
Based on the relationship between yield of winter wheat at different growth stages and meteorological factors, the actual yield can be segregated step by step. Based on the yield data of reviving period to heading date without meteorological disasters, the ideal yield were calculated with Lagrange's Interpolation Polynomial and the yield loss rate affected by meteorological disasters have been assessed. By analyzing the degree of different meteorological disasters and their effect on yield from turning green period to heading date, the model of evaluation on late frost loss was defined. Take Shangqiu station as representative in Huanghuai Area, the yield loss caused by frost from 1980 to 2006 were simulated and analyzed. The results shows that the average rate of yield loss was 11.7% and the heavy disaster years of yield loss can be above 30%.
Effects of soil water on crop growth and yield are performed on the changes of crop growing conditions and biomass growth. In this paper, long-term field experiment data at Zhengzhou Experiment Station were used to statistically analyze the relationships between crop growing conditions and biomass growth at current stage and soil water at previous stage. And the relationships between soil water and yield were also set up. Subsequently, optimum soil water and drought indexes were determined for different growth stages of winter wheat. All these results lay the foundation for dynamic evaluation of drought in winter wheat.
Variation in ear emergence time is critical for the adaptation of wheat (Triticum aestivum L.) to specific environments. The aim of this study was to identify genes controlling ear emergence time in elite European winter wheat germplasm. Four doubled haploid populations derived from the crosses: Avalon x Cadenza, Savannah x Rialto, Spark x Rialto, and Charger x Badger were selected which represent diversity in European winter wheat breeding programmes. Ear emergence time was recorded as the time from 1st May to heading in replicated field trials in the UK, France and Germany. Genetic maps based on simple sequence repeat (SSR) and Diversity Arrays Technology (DArT) markers were constructed for each population. One hundred and twenty-seven significant QTL were identified in the four populations. These effects were condensed into 19 meta-QTL projected onto a consensus SSR map of wheat. These effects are located on chromosomes 1B (2 meta-QTL), 1D, 2A (2 meta-QTL), 3A, 3B (2 meta-QTL), 4B, 4D, 5A (2 meta-QTL), 5B, 6A, 6B 7A (2 meta-QTL), 7B and 7D. The identification of environmentally robust earliness per se effects will facilitate the fine tuning of ear emergence in predictive wheat breeding programmes.
Winter wheat and spring maize strip intercropping system is widely practiced in northern China. In this study, a field experiment with typical winter wheat and spring maize strip intercropping systems was carried out in 2003–2004 and 2004–2005 seasons to investigate crop coefficient ( , defined as the ratio of actual crop evapotranspiration to reference crop evapotranspiration) and water-use efficiency (WUE, defined as the ratio of grain yield to total actual evapotranspiration) of intercropping systems in the Huang-Huai-Hai Plain of China. Crop coefficient values of sole winter wheat varied in ranges of 0.26–0.36, 1.09–1.15 and 0.27–0.41 at initial, mid and late season in two seasons, respectively. values of sole spring maize varied in 0.36–0.37, 1.18–1.19 and 0.22–0.28 at initial, mid and late season in two seasons, respectively. values of winter wheat/spring maize intercropping system varied in 0.31–0.35, 1.14–1.23 at initial and middle wheat growing season, in 0.65–0.70 at wheat-maize co-growing period, and in 1.24–1.25 and 0.21–0.27 at middle and late maize growing season in two seasons, respectively. Compared to yields of spring maize and winter wheat in monoculture, total grain yield (wheat + maize) of winter wheat/spring maize intercropping system increased by 39% and 98%, respectively. Average WUE in the intercropping system was 21.72 kg ha mm , which was 23% less than that of the sole maize, but 4% greater than that of the sole wheat (4%). Therefore, although winter wheat/spring maize intercropping system does not improve WUE, it may significantly raise yield, which is helpful to ensure food safety in northern China.
Cropping systems comprising winter catch crops followed by spring wheat could reduce N leaching risks compared to traditional winter wheat systems in humid climates. We studied the soil mineral N (Ninorg) and root growth of winter– and spring wheat to 2.5 m depth during 3 years. The roots of the winter and spring wheat penetrated the soil at a similar rate (1.3 mm °C day-1) and by virtue of its longer growing period, winter wheat reached depths of 2.2 m, twice that of spring wheat (1.1 m). The deeper rooting of winter wheat was related to much lower amounts of Ninorg left in the 1 to 2.5 m layer after winter wheat (81 kg Ninorg ha-1 less). When growing winter catch crops before spring wheat, N content in the 1 to 2.5 m layer after spring wheat was not different from that after winter wheat. The results suggest that due to its deep rooting, winter wheat may not lead to as high levels of leaching as it is often assumed in humid climates. Deep soil and root measurements (below 1 m) in this experiment were essential to answer the questions we posed.
A crop managed in a traditional way was monitored over a complete sugar beet/winter wheat/potato/winter wheat rotation cycle from 2004 to 2008. Eddy covariance, automatic and manual soil chamber, leaf diffusion and biomass measurements were performed continuously in order to obtain the daily and seasonal Net Ecosystem Exchange (NEE), Gross Primary Productivity (GPP), Total Ecosystem Respiration (TER), Net Primary Productivity (NPP), autotrophic respiration, heterotrophic respiration and Net Biome Production (NBP). The results showed that GPP and TER were subjected to important inter-annual variability due to differences between crops and to climate variability. A significant impact of intercrop assimilation and of some farmer interventions was also detected and quantified. Notably, the impact of ploughing was found to be limited in intensity (1–2 μmol m s ) and duration (not more than 1 day). Seasonal budgets showed that, during cropping periods, the TER/GPP ratio varied between 40 and 60% and that TER was dominated mainly by the autotrophic component (65% of TER and more). Autotrophic respiration was closely related to GPP during the growth period. The whole cycle budget showed that NEE was negative and the rotation behaved as a sink of 1.59 kgC m over the 4-year rotation. However, if exports are deducted from the budget, the crop became a small source of 0.22 (±0.14) kgC m . The main causes of uncertainty with these results were due to biomass samplings and eddy covariance measurements (mainly, uncertainties about the threshold determination). The positive NBP also suggested that the crop soil carbon content decreased. This could be explained by the crop management, as neither farmyard manure nor slurry had been applied to the crop for more than 10 years and because cereal straw had been systematically exported for livestock. The results were also strongly influenced by the particular climatic conditions in 2007 (mild winter, and dry spring) that increased the fraction of biomass returned to the soil at the expense of harvested biomass, and therefore mitigated the source intensity. If 2007 had been a ‘normal’ year, this intensity would have been twice as great. This suggests that, in general, the rotation behaved as a small carbon source, which accords with similar studies based on multi-year eddy covariance measurements and export assessment and with modelling or inventory studies analysing the evolution of crop soil organic carbon (SOC) on a decennial scale.
A set of 142 winter wheat recombinant inbred lines (RILs) deriving from the cross Heshangmai X Yu8679 were tried in four ecological environments during the seasons 2006 and 2007. Nine agronomic traits comprising mean grain filling rate (GFR(mean)), maximum grain filling rate (GFR(max)), grain filling duration (GFD), grain number per ear (GNE), grain weight per ear (GWE), flowering time ( FT), maturation time (MT), plant height (PHT) and thousand grain weight (TGW) were evaluated in Beijing ( 2006 and 2007), Chengdu ( 2007) and Hefei ( 2007). A genetic map comprising 173 SSR markers and two EST markers was generated. Based on the genetic map and phenotypic data, quantitative trait loci (QTL) were mapped for these agronomic traits. A total of 99 putative QTLs were identified for the nine traits over four environments except GFD, PHT and MT, measured in two environments (BJ07 and CD07), respectively. Of the QTL detected, 17 for GFRmean, 16 for GFRmax, 21 for TGW and 10 for GWE involving the chromosomes 1A, 1B, 2A, 2D, 3A, 3B, 3D, 4A, 4D, 5A, 5B, 6D and 7D were identified. Moreover, 13 genomic regions showing pleiotropic effects were detected in chromosomes 1A, 1B, 1D, 2A, 2B, 2D, 3A, 3B, 4B, 4D, 5B, 6D and 7D; these QTL revealing pleiotropic effects may be informative for a better understanding of the genetic basis of grain filling rate and other yield-related traits, and represent potential targets for multi-trait marker aided selection in wheat.
Optical sensor-based N management strategies are promising approaches to improve N-use efficiency (NUE) and reduce environmental pollution risk. The objective of this study was to evaluate an active optical sensor-based in-season N management strategy for winter wheat (Triticum aestivum L.) in the North China Plain (NCP). Initially, 10 field experiments were conducted at four villages in NCP in the 2004/05, 2005/06, and 2006/07 growing seasons to evaluate the in-season N requirement prediction developed by Oklahoma State University. Then the N application rates, winter wheat grain yield, NUE, economic returns, residual N content after harvest and apparent N loss were compared among three different management systems on a total of 16 farmer fields in 2005/2006 and 14 farmer fields in 2006/2007. The systems included a sensor-based system, a soil test-based approach crediting soil residual mineral N (N-min) to different depth at different growth stages, and common farmer practices. Averaged across site-years, the sensor-based, soil N-min-based N management strategies, and farmer practices produced similar grain yields but used 67, 88, and 372 kg N ha(-1), respectively. Nitrogen-use efficiencies were 61.3, 51.0, and 13.1% for the three methods of N recommendations, correspondingly. Their residual N content in the soil and apparent N loss were 115, 122, and 208 kg N ha(-1), and 4, 15, and 205 kg N ha(-1), respectively. The optical sensor-based N management strategy is relatively easy to use, has better potential to improve NUE and economic returns, and reduces residual soil N content and apparent N loss than other methods currently used in the NCP.
The critical value of soil Olsen-P is the point above which the probability of crop yield response to fertilizer P is small or nil. Determining this critical value is fundamental when making appropriate P fertilizer recommendations. In this study, the critical values were determined for continuous maize (Zea mays L.)-winter wheat (Triticum aestivum L.) cropping systems from a 15-year field experiment across three sites in China using linear-linear, linear-plateau and Mitscherlich models. The mean critical values for maize using the three models ranged from 12.1 to 17.3 mg P kg-1 (average 15.3 mg P kg-1) and for winter wheat from 12.5 to 19.0 mg P kg-1 (average 16.3 mg P kg-1) among study sites. The mean critical value for maize was approximately 7% lower than that for winter wheat across all sites based on the three models. Critical values identified by the Mitscherlich model were 1.4 to 2.1 times those from linear-linear and 1.3 to 1.9 times of those from linear-plateau and were crop and site dependent. There was a significant negative correlation (P<0.05) between the mean critical value from the three models and the observed P uptake by either maize or wheat. Our study shows that the critical values can vary with sites, crops and models used, and thus caution should be taken when selecting the most appropriate one when making P fertilizer recommendations for agronomic return and to minimize chances of negative environment impact from overfertilization.