Baseline Sensitivity and Control Efficacy of Two Quinone Outside Inhibitor Fungicides, Azoxystrobin and Pyraclostrobin, Against Ustilaginoidea virens.

Rice false smut caused by the filamentous fungus Ustilaginoidea virens is a devastating grain disease in rice. Fungicides have been an important measure for the control of this disease. In this study, baseline sensitivities of 179 isolates of U. virens to the quinone outside inhibitor (QoI) fungicides azoxystrobin and pyraclostrobin were established. The distribution of the 50% effective concentration (EC50) values of each fungicide was unimodal. The frequency distribution of logarithmically transformed EC50 values fit or fit closer to a normal distribution. The ranges of EC50 values for azoxystrobin and pyraclostrobin were 0.001 to 0.864 and 0.001 to 0.569 µg/ml, with means and standard errors of the mean values of 0.203 ± 0.012 and 0.079 ± 0.006 µg/ml, respectively. There was a statistically significant and moderately positive correlation (n = 100, r = 0.469, P = 0.001) in sensitivity between these two fungicides. No cross-resistance was found between azoxystrobin, pyraclostrobin, and carbendazim or sterol demethylation inhibitor fungicides. Each fungicide had a significantly higher mean preventive efficacy compared with its curative efficacy. Field assays showed that the control efficacy of pyraclostrobin against rice false smut was greater than that of azoxystrobin. Pyraclostrobin had the best control of rice false smut in three rice varieties, with the control efficacy ranging from 81.5 to 95.5%, whereas azoxystrobin decreased the disease index by 64.1 to 69.2% under the same conditions. These results provide us a reference point in the management of U. virens and future QoI fungicide resistance monitoring programs.

Pre-Gelatinisation of Rice Flour and Its Effect on the Properties of Gluten Free Rice Bread and Its Batter.

In order to improve the quality of the gluten free rice bread (GFRB), pre-gelatinised rice flour (PGRF) was made and used to partially replace natural rice flour in the production of GFRB. The pre-gelatinisation parameters were optimised and the effects of PGRF on the quality of the GFRB and its batter were studied. The results showed that optimal PGRF was obtained when 50% total water was mixed with 1.0% rice flour and the mixture heated at 80 °C for 2 min. Supplementation with PGRF significantly improved the properties of GFRB by affecting its baking properties, textural properties, colour, and crumb grain features. Effects of PGRF on GFRB were mainly caused by the more closely packed gel structure of rice starch in the bread batter, the higher onset temperature during gelatinisation and the complex effect of PGRF on water-binding capacity in bread batter during the baking process. As the pre-gelatinisation parameters of flours and their effect on gluten-free baked products varied with grain variety, processing properties should be studied before using them, and emphasis should be placed on new techniques such as flour pre-gelatinisation to obtain gluten-free foods with improved quality.

[Life history traits of an Echinochloa crus-galli var. crus-galli population with extreme adaptations to rice planting systems]. / 特异性适应稻作系统的稗草种群生活史特性.

Long-term herbicide application may facilitate the adaptive evolution of weed populations. With Echinochloa crus-galli var. crus-galli population A from a rice field used for the experiment of effectiveness of herbicide in Nanling County, Anhui Province, we conducted common garden experi-ments with seeds of population A and three control populations collected from normal rice fields. Compared with the three control populations, population A had significantly lower seed production for individual plant, but higher 1000-seed weight. Population A had faster in seedling growth, higher in number of reproductive tillers, shorter life span, lower in height and biomass of individual plant, as well as lower in sensitivity to herbicide penoxsulam. Individuals from population A survived from 2× label dose (60 g·hm-2) of penoxsulam treatment at the three- to four-leaf stage showed significantly reduction in plant height, biomass, and mature seed production (1066 seeds per plant), but no difference in heading period, number of reproductive tillers, number of seeds per raceme and 1000-seed weight. The short lifespan, heavy seeds, dwarf architecture, more reproductive tillers and penoxsulam resistance made E. crus-galli var. crus-galli population A extremely adapting to rice planting systems, which should be prevented to spread to normal rice fields.

Quantitative monitoring of leaf area index in wheat of different plant types by integrating NDVI and Beer-Lambert law.

Normalized difference vegetation index (NDVI) is one of the most important vegetation indices in crop remote sensing. It features a simple, fast, and non-destructive method and has been widely used in remote monitoring of crop growing status. Beer-Lambert law is widely used in calculating crop leaf area index (LAI), however, it is time-consuming detection and low in output. Our objective was to improve the accuracy of monitoring LAI through remote sensing by integrating NDVI and Beer-Lambert law. In this study, the Beer-Lambert law was firstly modified to construct a monitoring model with NDVI as the independent variable. Secondly, experimental data of wheat from different years and various plant types (erectophile, planophile and middle types) was used to validate the modified model. The results showed that at 130 DAS (days after sowing), the differences in NDVI, leaf area index (LAI) and extinction coefficient (k) of the three plant types with significantly different leaf orientation values (LOVs) reached the maximum. The NDVI of the planophile-type wheat reached saturation earlier than that of the middle and erectophile types. The undetermined parameters of the model (LAI = -ln (a1 × NDVI + b1)/(a2 × NDVI + b2)) were related to the plant type of wheat. For the erectophile-type cultivars (LOV ≥ 60°), the parameters for the modified model were, a1 = 0.306, a2 = -0.534, b1 = -0.065, and b2 = 0.541. For the middle-type cultivars (30° < LOV < 60°), the parameters were, a1 = 0.392, a2 = -0.881, b1 = 0.028, and b2 = 0.845. And for the planophile-type cultivars (LOV ≤ 30°), those parameters were, a1 = 0.596, a2 = -1.306, b1 = 0.014, and b2 = 1.130. Verification proved that the modified model based on integrating NDVI and Beer-Lambert law was better than Beer-Lambert law model only or NDVI-LAI direct model only. It was feasible to quantitatively monitor the LAI of different plant-type wheat by integrating NDVI and Beer-Lambert law, especially for erectophile-type wheat (R2 = 0.905, RMSE = 0.36, RE = 0.10). The monitoring model proposed in this study can accurately reflect the dynamic changes of plant canopy structure parameters, and provides a novel method for determining plant LAI.

[Response of yield, quality and nitrogen use efficiency to nitrogen fertilizer from mechanical transplanting super japonica rice].

Five super japonica rice cultivars were grown by mechanical transplanting in field and seven N treatments with total N application rate of 0, 150, 187.5, 225, 262.5, 300 and 337.5 kg x hm(-2) respectively were adopted to study the effects of N rate on rice yield, quality and N use efficiency. The differences between N requirement for obtaining the highest yield and for achieving the best economic benefit were compared. With the increase of N fertilizer rate, the yields of five super japonica rice cultivars increased firstly and then descended, achieving the highest yield at the N level of 300 kg x hm(-2) ranging from 10.33-10.60 kg x hm(-2). Yield increase mainly attributed to the large number of spikelet, for the total spikelet number of each rice cultivar reached the maximum value at the 300 kg x hm(-2) N level. With the increase of N application, the rates of brown rice, milled rice, head milled rice and the protein content of the five super japonica rice cultivars were all increased, and the rates of brown rice, milled rice, head milled rice and the protein con- tent were higher at 337.5 kg x hm(-2) N level than at 0 kg x hm(-2) N level by 3.3%-4.2%, 2.9%-6.0%, 4.4%-33.7% and 23.8%-44.3%, respectively. While the amylose content, gel consistency and taste value of the five rice cultivars were all decreased, and the amylose content, gel consistency and taste value were lower at 337.5 kg x hm(-2) N level than at 0 kg x hm(-2) N level by 12.4%-38.9%, 10.3%-28.5% and 20.3%-29.7%, respectively. The chalkiness increased firstly and then decreased while the change of chalky rate varied with the cultivars. With the increase of N application, the N use efficiency, agronomic N use efficiency and physiological N use efficiency decreased while the N uptake of grain increased significantly. If the cost of N fertilizer was taken into account, the N fertilizer amount to obtain the optimal economic benefits would be 275.68 kg x hm(-2) with the corresponding yield of 9.97 t x hm(-2). Therefore, in the existing super rice production, classified management of N fertilizer would be required to meet differentiated demands of high yield, good quality, high efficiency, low N fertilizer input and so on.