Search

High temperature inhibits the growth and development of maize (Zea mays L.) and wheat (Triticum aestivum L.) seedlings. The current study attempts to elucidate the underlying mechanisms of exogenous trehalose for the improvement of maize and wheat responses to heat stress. Results show that, in maize seedlings, exogenously-supplied trehalose was able to effectively elevate the capacity of photosynthetic carbon assimilation and improve the carbohydrate content via up-regulating the transcript levels of key enzymes including phosphoenol pyruvate carboxylase (PEPC), NADP-malate dehydrogenase (NADP-MDH), NADP-malic enzyme (NADP-ME), pyruvate phosphate dikinase (PPDK) and Ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit. Besides, it was also able to improve C4 pathway enzyme activities, including PEPC, NADP-MDH, NADP-ME and Ribulose-1,5-bisphosphate carboxylase (RUBPCase). In wheat seedlings, exogenously-supplied trehalose promoted photosynthetic carbon assimilation by elevating the activity of RUBPCase. These results show that exogenous trehalose improved photosynthetic carbon assimilation capacities in maize and wheat seedlings under heat stress through different mechanisms. [ABSTRACT FROM AUTHOR]

Endophytic bacteria are those that colonise the internal tissues of plant without negative impact on plant health. This work aims to isolate the endophytic bacteria colonising Triticum vulgare and Phragmites australis and evaluate their compatibility as biostimulants to maize. Three of the six obtained isolates were selected upon their surpassing ability to stimulate the growth of maize seedlings (maximum of 18% increase in germination and 2.4-fold increase in the number of lateral roots). These isolates were molecularly identified as Klebsiella MK2R2, Bacillus B2L2 and Enterobacter E1S2. The response of maize seedlings to the combined effect of these isolates revealed that Bacillus B2L2, containing treatments, surpassed the other treatments in growth vigour parameters and upon this result these treatments were applied in a field experiment either alone or in combination with 100% N fertilisation. Maize plants, inoculated with Klebsiella MK2R2 and Bacillus B2L2 either alone or in combination with Enterobacter E1S2 in the presence of urea, surpassed significantly other treatments as the weight of ear increased almost two times and the number of grains increased 1.8 times compared to the control values. It could be concluded that the obtained strains are compatible biostimulants to maize. [ABSTRACT FROM AUTHOR]

Quantitative profiling of total phenolic content (TPC) and antioxidant activity (AOA) in seeds, sprouts, and grasses of corn (Zea mays L.), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.) were performed. TPC and AOA were strongly correlated and increased with days. Grasses between 10 and 13 days showed the highest TPCs and AOA. The AOA in sprouts and grasses were a fifth and two-thirds of ascorbic acid (AA) standard, respectively, which are higher than in several popular natural antioxidants. Further cell-based studies or in vivo studies could be considered in future to draw more valuable information related to human health. [ABSTRACT FROM AUTHOR]

Objectives: Data on the glycaemic index (GI) of foods commonly consumed in Botswana are lacking. The present study aimed to evaluate the GI of some of the staple carbohydrate-rich foods eaten in Botswana. Design, setting and subjects: Fifty university student volunteers were divided into five groups. Members of each group consumed different test foods based on wheat, maize, sorghum, millet and morama beans to supply 50 g of available carbohydrate after 10-12 hours of overnight fasting. GI was determined using a standard method with white bread. Outcome measures: The GI values were calculated after measuring blood glucose levels before and after ingestion at 0, 15, 30, 45, 60, 90 and 120 minutes. Results: The results showed a clear variation in the GI values for the same food when consumed by different individuals. In addition, variations were observed in the GI values of test foods based on the same material. On average, wheat-based foods exhibited the highest GI values (103.1), followed by millet-based foods (95.3), sorghum-based foods (92.5), maize-based foods (9.1) and morama-based foods (86.4). Of the tested food, mapakiwa (wheat-based) had the highest GI (110.6) whereas roasted morama had the lowest GI (82.8). Conclusion: These results could form the basis of dietary advice to consumers, and particularly patients with diabetes. Further studies are needed on more of the commonly consumed foods in Botswana. [ABSTRACT FROM AUTHOR]

Hydrophobic prolamins are endosperm storage proteins accounting for about 40% of the total protein in most cereal seeds. Despite the absence of a reference method, several procedures have been periodically published to quantify prolamins in cereals. The aim of this study was to compare a conventional fractionation assay (LND) vs three other methods: one based on sequential extractions (HAM) and two rapid turbidimetric procedures (L&H andDRO). Prolamins were extracted in duplicate on barley, corn and wheat samples. For the turbidimetric prolamin evaluation in barley and wheat, a universally available purified gliadin, as alternative to purified zein, was also tested as standard reference material (SRM). The extraction prolamin values were different among grain types (P<0.01) and methods (P<0.01) without interaction (P>0.05). LND agreed sufficiently well both with HAM and with L&H methods (R2=0.664 and R2=0.703, respectively, P<0.01). On all tested cereals, LND and L&H gave similar prolamin extraction values (P>0.05), whereas a higher prolamin quantification was obtained using HAM (P<0.05). Overall, DRO did not provide similar comparison and performance parameters with respect to other method comparisons. The effect of changing purified zein with purified gliadin was noteworthy only for L&H, both for wheat and barley samples (P<0.01). Considering the increasing attention of animal nutritionists on prolamins, our results could get useful information for routine laboratory analysis. [ABSTRACT FROM AUTHOR]

Calocybe indica, known as milky white mushroom, grows and cultivated in the sub-tropical and temperate zones of South Asia. We investigated the most suitable supplements and their levels for the commercial cultivation of milky white mushroom. Rice bran, maize powder, and wheat bran with their different levels (10, 20, 30, 40, and 50%) were used as supplements to evaluate the yield and yield contributing characteristics of C. indica. Primordia initiation was observed between 13.5 and 19.3 days. The results indicated that the 30% maize powder supplement was effective for producing viable fruiting bodies. The maximum diameters of the pileus and stalk were observed with 30% maize powder. The highest biological and economic yield and biological efficiency were also obtained with 30% maize powder as a supplement. The results indicate that increasing the supplement level resulted in less biological efficiency, and that 30% maize powder was the best supplement level for rice straw substrate to cultivate milky white mushrooms. [ABSTRACT FROM AUTHOR]

Quantifying diurnal patterns of water use efficiency (WUE) and radiation use efficiency (RUE) for wheat and maize is important for assessing water use by plants and crop productivity. Water and carbon dioxide fluxes from an irrigated wheat-maize double-crop field from November 2002 to October 2003 were measured using the Eddy Covariance method. Evident differences were observed between the diurnal patterns of WUE for wheat and maize. The WUE values of wheat peaked near 9, 15 and 12 mg CO2 g H2O in the morning, and then decreased linearly with time and recovered in the late afternoon (4:00pm) before sunset in March, April and May, respectively. The WUE of maize increased after sunrise and retained stable values of 6, 14 and 12 mg CO2 g H2O from mid-morning to mid-afternoon (10:00am -2:00pm) and then decreased slowly with time until sunset in July, August and September, respectively. Similar patterns were observed in the RUE of wheat and maize. Over the three months of the study, averaged RUE was 1.76 g C MJ-1 for the wheat crop and 1.87 g C MJ-1 for the maize crop. A coupled photosynthesis and transpiration model was used to simulate the diurnal variations in WUE under variable climate conditions. Measurement results and sensitivity analysis show that the difference in the diurnal variation pattern in WUE between wheat and maize resulted from the different carbon fixing mechanisms of wheat and maize. [ABSTRACT FROM AUTHOR]

CO2 flux was measured continuously using the eddy covariance technique in a wheatmaize rotation system in the North China Plains from October 2002 to October 2006. The annual and seasonal variation of ecosystem respiration and the bio-environmental controls on them were investigated. The results show that ecosystem respiration (Rec) in the cropland increased exponentially with soil temperature at 5 cm depth. The temperature sensitivity coefficient (Q10) for ecosystem respiration varied from 3.5 to 5.4 for wheat and from 2.4 to 4.5 for maize. In the wheat growing season, monthly average R0 (ecosystem respiration at 0°C) increased linearly with soil temperature and logarithmically with leaf area index (LAI). Monthly average Q10 decreased logarithmically with R0. Residual Rec was significantly correlated with LAI. After considering LAI, the modified Q10 model could estimate Rec better than before. The simulation results show that annual ecosystem respiration in the wheat-maize rotation system in the North China Plains was 1327, 1348, 1040 and 1171 gC m-2 yr-1 for the 4 years of the study. As a 4-year average, seasonal mean ecosystem respiration in wheat (2.60 gC m-2 day-1) was much lower than in maize (6.09 gC m-2 day-1). However, integrated ecosystem respiration for the wheat growing season (566 gC m-2) was slightly higher than that for maize (520 gC m-2). These account for 46.4 and 42.6% of the annual values, respectively. [ABSTRACT FROM AUTHOR]

Stochastic efficiency with respect to an exponential utility function was used to determine utility-efficient water-conserving irrigation schedules for wheat and maize based on certainty equivalents. Total gross margin risk resulting from production risk of alternative deficit irrigation practices was quantified using an irrigation simulation model and stochastic budgeting procedures. Results showed increasing production variability with increasing levels of deficit irrigation, especially when rainfall has significant potential to contribute to the production process. Risk-averse decision makers are more willingly to adopt deficit irrigation schedules for maize due to increased effective rainfall. The conclusion is that the potential to use rainfall more effectively through deficit irrigation is a key variable determining adoption of deficit irrigation strategies by risk-averse decision makers. Localized weather forecasts may improve acceptance of deficit irrigation by risk-averse decision makers. The value of information for weather forecast might be low because of high risk premiums placed on full irrigation by risk-averse decision makers. [ABSTRACT FROM AUTHOR]

This paper tests the existence of price asymmetry in South African futures markets for white and yellow maize, wheat and sunflower seeds using a dynamic price asymmetry model The sum of coefficients test and the speed of adjustment test are used to determine whether or not prices move up in the same fashion as they move down, over daily and weekly data frequencies. Out of the four commodity futures markets studied over varying data frequencies, only daily wheat is price asymmetric. Wheat daily prices respond faster to price decreases than to price increases. The implication of the results is that past prices do affect current prices and contain information. Hence, the weak-form efficient market hypothesis appears to be contradicted for wheat futures market. Another important implication of the results is that implementing policies accounting for asymmetric behavior through price limit and margin policies will improve the functioning and stability of wheat futures market in South Africa. [ABSTRACT FROM AUTHOR]

Fusarium graminearum (teleomorph Gibberella zeae) is a significant pathogen of wheat and corn. F. graminearum forms multicellular macroconidia that play an important role in dissemination of the disease. The spatial pattern of morphogenesis in germinating macroconidia is described. Germ tubes preferentially emerge from the apical cells in a bipolar pattern that appears to be common to filamentous fungi. Chitin deposition occurs at two locations: the spore apices and cortical regions of macroconidial cells that subsequently produce a germ tube. The spatial pattern of morphogenesis requires the presence of functional microtubules, which may be responsible for the transport of key polarity factors to specific sites. These observations suggest that F. graminearum possesses a regulatory system that marks germ tube emergence sites. Perturbation of this system may represent an effective approach for inhibiting colonization of host plant surfaces. [ABSTRACT FROM AUTHOR]

A random field model, consisting of a regional trend component and a local interaction component, describes the spatial pattern of corn and wheat yields in the High Plains. The presence of spatial autocorrelation in the local component raises interesting statistical estimation problems. Temporal variations in the slope and interaction parameters are a function of climatic fluctuations. The local component reflects intercounty spatial autocorrelation in precipitation patterns. [ABSTRACT FROM AUTHOR]