Ozone, as a strong oxidative agent, is used to eradicate microbial, but this treatment affects also the quality of grain. The objective of this study was to evaluate the effect of ozonation of winter wheat grain harvested in different cropping and tillage systems on the number and composition of fungi colonizing grain surface and on the contents of total-phosphorus (P), phytate-P and phenolic acids. Wheat was sown in a two-factor experiment established with the method of randomized sub-blocks. The first order factor included cropping systems: (a) crop rotation and (b) monoculture, whereas the second order factor included tillage systems: (1) conventional (CT); (2) reduced (RT); and (3) herbicide. Ozonation significantly reduced the count of fungi on the surface of grain, especially on the grain harvested from wheat monoculture. In addition, it increased the content of phytate-P but decreased the content of total-P. A higher total-P content was determined in the grain harvested from monoculture than from crop rotation, whereas phytate-P content in the grain from crop rotation was higher than from monoculture. The ozonated grain harvested from CT plots was characterized by a higher content of phytate-P and a lower content of total-P, compared to the non-ozonated grain. Ozonation also increased the content of phenolic acids in the grain, especially in that harvested from the RT system.

The objective of this study was to evaluate the effect of growth regulator applications on yield and physiological parameters of winter wheat (Triticum aestivum L.) under water deficit. Water deficit was induced artificially by using rain-out shelters in period between booting and late milk ripeness. The effect of growth regulators was evaluated in two contrast years in terms of yield formation (2014-2015). In both years the water deficit caused a significant reduction of grain yield. The negative effect of water deficit was partly alleviated by application of growth regulators. However, the effect of individual growth regulators varied depending on year. In favourable conditions for grain filling (2014) the alleviating effect was more pronounced in application of azoxystrobin which slows down the leaf senescence. On the contrary, in the year with suitable conditions for tillering (2015), the alleviating effect was most apparent in application of chlormequate-chloride. The applications of trinexapac-ethyl and ethephon showed small reduction of negative effect of water deficit consistently in both years. The CO2 assimilation rate and stomatal conductance were recovered particularly by applications of chlormequate-chloride and azoxystrobin. Chlorophyll content and chlorophyll fluorescence parameters were more affected by water deficit in 2014, and the alleviating effect of growth regulators corresponded with yield response.

Thesis (MSc Food Sc)--Stellenbosch University, 2016. | ENGLISH ABSTRACT: See full text for abstract. | AFRIKAANSE OPSOMMING: Sien volteks vir opsomming.

Isotopic carbon discrimination (Δ13C) of winter wheat grain grown under different water and nitrogen supplies was determined. In two field experiments during years 2004-2007 (A) and 2008-2013 (B), a water shortage was induced from the flowering stage on with a mobile shelter (S), while an optimal water supply was ensured with drip irrigation (I), and a rain-fed crop served as the control treatment (R). Water supply had a statistically significant effect on grain Δ13C values in both experiments (P < 0.01). The average values of grain Δ13C in treatments I, R and S were 19.43, 18.68 and 17.70‰ (A); and 20.36, 19.60 and 18.13‰ (B). Grain Δ13C was in a significant linear relationship (P < 0.01) with the amount of water supplied by precipitation or irrigation. The regressions suggested that grain Δ13C increased by 1.14‰ and 1.16‰ (A), and 0.98‰ or 0.96‰ (B) for every 100 mm of water from January and March, respectively, until the early dough stage (r = 0.79-0.74, P < 0.05). Pooled data for the whole period 2004-2013 showed increases of 1.06‰ and 1.08‰ (r = 0.91 and 0.82, P < 0.05) for 100 mm of water, respectively. The results of the experiment confirmed the stable and predictable effect of water supply on wheat grain Δ13C.

To study the effects of application of salicylic acid (SA) on the antioxidant system and photosystem II (PS II) in wheat seedlings we used two different experiments. The first method was carried out by immersing roots in Hoagland's nutrient solution containing 0, 0.25, or 2.5 mM SA, and the second method was performed by spraying two-week-old seedlings with the same SA concentrations. After 24 h, chlorophyll fluorescence, thylakoid membrane proteins, antioxidant enzyme activities, and reactive oxygen species were measured. The low concentration of SA caused a significant increase in the antioxidant enzyme activities. However, the treatment with 2.5 mM SA resulted in an increase in the non-photochemical quenching coefficient and a decrease in the antioxidant enzyme activities, the quantum yield of PS II photochemistry, and the photochemical quenching, especially in the first method of application. All these results indicate that the effects of SA on PS II and the antioxidative defense system were dependent on the concentration used and the method of application.

Daily data from 40 meteorological stations in the Huang-Huai-Hai Plain from 1955 to 2013 were analyzed using the Mann-Kendall test and partial correlation to determine the temporal trends of meteorological factors and their impacts on water requirements of winter wheat in different growing periods. Results showed that water requirements during the whole growing period in the Huang-Huai-Hai Plain were between 374 and 485.2 mm with an average of 412 mm in the past 59 years. In general, the value declined by 4 mm per decade. The distribution was ribbon-like, decreasing from the N to the S. Average wind speed, humidity, and sunshine hours declined significantly (α = 0.01, 0.05, and 0.01, respectively). Average vapour pressure and temperature increased significantly (α = 0.01). Only rainfall in Dongtai, Gaoyou, and Zhumadian could meet the water requirement of winter wheat over the whole growing period. Response of crop water requirement (ETc) to meteorological factors change was linear and the order of impact on ETc was vapour pressure, temperature, wind speed, and sunshine hours, while humidity had little impact on ETc. Among the impacting factors, vapour pressure was in positive relation with ETc.

Two wheat cultivars (Gaocheng8901 and Yumai50) grown were used to investigate the effect of sulphur fertilizer on the glutenin macropolymer (GMP) size distribution and the contents of glutenin subunits in wheat. The results showed that the contents of GMP, high molecular weight glutenin subunit (HMW-GS) and low molecular weight glutenin subunit (LMW-GS) were improved by sulphur fertilizer under lower nitrogen (N) condition in both cultivars. Under normal N (240 kg N/ha) conditions, sulphur application improved the contents of HMW-GS, LMW-GS and GMP within sulphur rates from 30-60 kg/ha, while decreased when sulphur rate of 90 kg/ha. The volume percentage of GMP particles < 60 μm decreased within sulphur rates from 30-90 kg/ha under lower N treatments. Under normal N condition, the volume percentage of GMP particles > 60 μm increased within the sulphur rates from 30-60 kg/ha, while decreased when excessive sulphur of 90 kg/ha was applied. It is suggested that appropriate sulphur fertilizer was favourable for the formation of large GMP particles, but too much of it was unfavourable under normal nitrogen condition. Sulphur fertilizer did not significantly affect the number distribution of GMP particles in both cultivars. The volume percentage of GMP particles > 60 µm was positively correlated with H/LMW-GS (the ratio of HMW-GS and LMW-GS) and GMP content. It indicated that larger GMP particles had more the ratio of HMW-GS and LMW-GS. And the higher the proportion of larger particles, the higher the content of GMP in wheat grain.

Improving wheat quality for processing and health. 1st Meeting of the Expert Working Group on Improving Wheat Quality for Processing and Health

Retrogradation is the process of starch recrystallization, and it profoundly affects the quality, acceptability and shelf-life of starch-containing foods. The influence of glutelin on the wheat starch retrogradation was studied in this paper. Glutenin was isolated from wheat flour, and its effect on retrogradation of wheat starch, amylose and amylopectin was investigated with UV–Vis (starch-iodine), IR and ¹³C NMR. The results showed that glutenin probably interacted with amylose during gelation and retrogradation of starch. The results of IR showed that the addition of glutenin to wheat starch reduced the number of hydrogen bonds formed between amyloses during retrogradation. The ¹³C NMR results suggested that tyrosine (Tyr) of glutenin might combine with amylose at the first carbon atom when they were mixed homogeneously and such combination was strengthened during retrogradation. Glutenin and amylose formed double helix with each other completely and hindered amylose–amylose short-term retrogradation of wheat starch, and glutenin would no longer inhibit the retrogradation of starch when all of the Tyr formed hydrogen bond with amylose. These results suggest that glutenin could play a powerful role in retarding the retrogradation of amylose, which is very important for the food industry.

A field experiment was conducted at Ranchi (Jharkhand) during rabi season of 2009-10 to 2011-12 with wheat cultivar K 9107 sown on three dates (Nov 20,Dec 5 and Dec 20) to calibrate and validate the CERES-wheat model. There was a good agreement between simulated and observed wheat yields, days to anthesis and days to maturity. The validated model was used to study the impact of intra seasonal temperature variation on wheat. The sensitivity analysis of CERES wheat model, with respect to temperature variations and wheat yield, revealed that increase in temperature above the normal values to 3 oC, showed considerable yield reduction (12- 17 per cent) under different sowing dates. Similarly, with decrease in seasonal temperature up to 3oC, the yield enhancement by 12-16 per cent was observed. Sensitivity of CERES wheat model to incremental units of intra seasonal temperature showed a gradual decrease in yield as well as days to maturity under varied sowing dates. Increase in temperature ( 3 oC from normal) during 2nd fortnight of January (16-31st ) was observed to be the most detrimental for wheat crop with respect to its yield for timely sowing date (20thNov) whereas it would be maximum during 2nd fortnight of February (15-28th) for moderately normal sown (5th Nov) and late sown crops (20thDec).