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.
Facing and controlling the adverse effects of global warming on crop production, especially under arid and semi arid conditions is an important question, which must be addressed by research work. This may be achieved by alternating crop phonological properties including the vernalization stage, essential for the vegetative/reproductive transition of winter wheat ( L.). Shortening vernalization, during spring, can be a suitable method for the earlier production of crop plants, especially under stress conditions. Accordingly, it was hypothesized that it is possible to shorten vernalization, using priming (seeds) and spraying (plants) treatments while achieving optimum yield, in winter wheat, under the arid and semi arid conditions of Isfahan, Iran. The objective was to investigate the effects of plant growth regulators including gibberellic acid (GA, 100 mg/l), kinetin (100 and 200 mg/l), 6-benzyl adenine (BA6, 50 mg/l) and cold stratification on shortening vernalization in winter wheat. The research was a split plot experiment on the basis of a completely randomized block design, with four replicates, conducted in 2016. Different traits including number of fertile tillers (NFT), number of grains per spike (NGS), weight of 1000 grains (W1000), number of spikelet per spike (NST), grain yield (GY), protein percentage (PRO), and moist gluten percentage (MGP) were determined. The results indicated that priming and spraying winter wheat with the single or combined use of GA, kinetin and BA6 is the most suitable replacement for vernalization and increasing grain yield, under arid and semi arid conditions. However, priming winter wheat with cold stratification was not as effective, compared with the use of plant growth regulators. The highest grain yield (15.13 t/ha) was resulted by autumn planting + B8 (GA + BA6), followed by spring planting + GA and B9 (14.82 t/ha). Spraying wheat planted in spring (without priming and vernalization) with kinetin + GA3+GA7 (100 mg/l), increased PRO and MGP. The important results of this research work are: 1) planting winter wheat as spring wheat (vernalization not required) resulted in optimum yield amounts by priming and spraying techniques using gibberellins, kinetin and 6-benzyl adenine. This is of significance, with respect to the issue of global warming. 2) Shortening vernalization in winter wheat, which is especially important under arid and semi arid conditions, as the plant is subjected to different stresses including drought. 3) Improving wheat grain quality by the increased rate of protein and gluten. It is possible to plant winter wheat under arid and semi arid conditions using gibberellins, kinetin and benzyl adenine. Such a method results in alleviating the adverse effects of global warming on wheat production. It is also possible to plant winter wheat under different stresses including drought and cold by controlling the vernalization process.
Crop protection agents are widely used in modern agriculture and exert direct effects on non-target microorganisms such as yeasts. Yeasts abundantly colonize wheat grain and affect its chemical composition. They can also limit pathogen growth. This study evaluated the sensitivity of yeast communities colonizing winter wheat kernels to benzimidazole, strobilurin, triazole and morpholine fungicides, trinexapac-ethyl, a commercial mixture of -nitrophenol+ -nitrophenol+5-nitroguaiacol, and chitosan applied during the growing season of winter wheat and in vitro in a diffusion test. A molecular identification analysis of yeasts isolated from winter wheat kernels was performed, and nucleotide polymorphisms in the gene (G143A) conferring resistance to strobilurin fungicides in yeast cells were identified. The size of yeast communities increased during grain storage, and the total counts of endophytic yeasts were significantly (85%) reduced following intensive fungicide treatment (fenpropimorph, a commercial mixture of pyraclostrobin, epoxiconazole and thiophanate-methyl). This study demonstrated that agrochemical residues in wheat grain can drive selection of yeast communities for reduced sensitivity to xenobiotics. A mutation in the gene (G143A) was observed in all analyzed isolates of the following azoxystrobin-resistant species: , , and Agrochemicals tested in vitro were divided into four classes of toxicity to yeasts: (1) tebuconazole and a commercial mixture of flusilazole and carbendazim - most toxic to yeasts; (2) fenpropimorph and a commercial mixture of pyraclostrobin and epoxyconazole; (3) propiconazole, chitosan, thiophanate-methyl and a commercial mixture of -nitrophenol, -nitrophenol and 5-nitroguaiacol; (4) trinexapac-ethyl and azoxystrobin – least toxic to yeasts. It was found that agrochemicals can have an adverse effect on yeast abundance and the composition of yeast communities, mostly due to differences in fungicide resistance between yeast species, including the clinically significant .
In order to investigate level and potential sources of polycyclic aromatic hydrocarbons (PAHs) in wheat fields affected by coal combustion in Henan and Shaanxi Provinces and to investigate distribution and transfer of PAHs in winter wheat grown in the areas, various tissues of the crop and the corresponding rhizosphere soils were collected during the harvest season of winter wheat. The mean concentrations of USEPA 15 priority PAHs (sum of the three- to six-ring PAHs) ranged from 486 to 1117 μg kg−1 in the rhizosphere soils, indicating serious PAH contamination. Based on both the isomeric ratios of PAHs and a principal component analysis (PCA), the main sources of PAHs in the agricultural soils were from combustion of biomass, coal and petroleum, and petroleum. ∑15PAHs were significantly (p < 0.001) higher in the roots (287–432 μg kg−1) than those in aerial tissues (221–310 μg kg−1). There were two decreasing gradients of PAH concentrations, one from roots, stems to leaves, and the other from glumes to grains. Regardless of sampling sites, most PAHs detected in the roots and in the aerial tissues were three-ring PAHs (acenaphthene, acenaphthylene, fluorene, phenanthrene, and anthracene) and the percentages of three-ring PAHs were much higher in the aerial tissues (72.5–82.7%) than in the roots (49.5–74.0%) and in the rhizosphere soils (36.3–65.7%). The distribution of PAHs with different ring numbers in the stems, leaves, and glumes was quite similar to each other but was significantly different from that of the roots and rhizosphere soils. Combined with significant results from partial correlation and linear regression models, the present study suggested that partial three- to four-ring PAHs in the aerial tissues are derived from root-soil uptake and that six-ring PAHs may come from the air-to-leaf pathway, although the quantity contribution of foliar uptake and root uptake was yet to be further studied.
Reclaimed water reuse has become an important means of alleviating agricultural water shortage worldwide. However, the presence of endocrine disrupters has roused up considerable attention. Barrel test in farmland was conducted to investigate the migration of nonylphenol (NP) and bisphenol A (BPA) in soil-winter wheat system simulating reclaimed water irrigation. Additionally, the health risks on humans were assessed based on US EPA risk assessment model. The migration of NP and BPA decreased from the soil to the winter wheat; the biological concentration factors (BCFs) of NP and BPA in roots, stems, leaves, and grains all decreased with their added concentrations in soils. The BCFs of NP and BPA in roots were greatest (0.60–5.80 and 0.063–1.45, respectively). The average BCFs of NP and BPA in winter wheat showed negative exponential relations to their concentrations in soil. The amounts of NP and BPA in soil-winter wheat system accounted for 8.99–28.24% and 2.35–4.95%, respectively, of the initial amounts added into the soils. The hazard quotient (HQ) for children and adults ranged between 10 and 1, so carcinogenic risks could be induced by ingesting winter wheat grains under long-term reclaimed water irrigation.
Selection of the best wheat variety for cellulosic ethanol production is very important. With dozens of varieties available, information on the sugar yield of different straws is needed to help farmers choose the most profitable wheat variety, for both grain yield and straw yield. Thirty winter wheat lines from the Pacific Northwest of the US were chosen for analysis based on historical and current production. Two pretreatment methods, dilute acid and hot water, were compared to determine the optimum pretreatment condition for wheat straw. Using the optimum dilute acid pretreatment condition, sugar yields from the straw of the 30 wheat varieties were compared. The differences in variety performance were then evaluated based on relationships among several measured parameters, including straw yield, grain yield, and chemical composition of biomass. The ranges of chemical composition for the 30 wheat straw varieties were 33.7–36.3% glucan (proxy for cellulose), 16.8–19.5% xylan (proxy for hemicellulose), and 18.4–20.6% lignin. Results also showed significant differences in total sugar recovery, which varied between 0.239 and 0.401 g g dry matter of raw biomass across wheat straw varieties. Among the 30 tested varieties, Weatherford was selected as the best for dual-purpose wheat because it ranked highest in straw yield and potential sugar production per area and 6th-highest in grain yield.