A New Hybrid Model for Panicle Growth in Rice (Oryza sativa L.)

A significant positive correlation was found between grain yield of rice and rate of filling. We developed an hybrid model (combining both Richard's function and quadratic polynomial in one model) for calculating the filling rate. This model is found to be the best fit for panicle development in rice.     

热量条件变化对积温及作物生长季的研究

通过研究热量条件的变化,分析原阳1981—2012年热量奈件（月、四季及≥0℃、≥10℃的活动积温及持续日数）的变化特征,建立多年平均气温与积温和持续日数的线性相关关系。结果表明,原阳县作物生长季内平均气温较20世纪80年代上升0．5℃。≥0℃的初日、终日分别提前11d和推后8d,作物生长期延长19d;≥0℃的积温增加153．9℃·d;≥10℃的初日、终日以及持续日数与80年代相比无明显变化。年平均气温与≥0℃、≥10℃积温有显著的线性相关关系。     

Effect of the Interaction between Cultural Condition and Genotype on Spike Morphogenesis in Spring Wheat

Abstract

The number of grains per spikelet and the number of spikelets per spike are important factors that influence grain yield in wheat. Three wheat genotypes in four foreign groups (OA, OC, OH and OJ) differing in spike type and Japanese cultivars (cvs) were grown under various combinations of seeding densities and fertilization levels. In all groups, the spikelet number per spike and the spike length at maturity were highest at low seeding densities and high levels of fertilization. The OA group (Nepal) and Haruyutaka (Japanese cv) gave a weak response in spikelet number per spike, while the OJ group (Xinjiang Uygur, China) gave a weak response in spike length. The OC group (except for T6), the OH group (Tibet) and Japanese cvs (except for Haruyutaka) responded to treatments in both spikelet number per spike and spike length. The T6 genotype in the OC group (Nepal) gave a weak response in both spikelet number per spike and spike length. Although the OA group had the longest spikes and the OJ group had the shortest spikes, there was no difference in the duration of spike elongation between the OA group and the OJ group. Spike length appeared to be determined mainly by the rate of spike elongation and was not restricted by the dry weight of the spike during the growth phase of the spike.     

Dry season survival,diapause duration and timing of diapause termination in the millet stem borer,Coniesta ignefusalis (Hampson) (Lepidoptera: Pyralidae) in Northern Ghana

Studies were conducted between 1996 and 1997 in Northern Ghana on the dry season survival tactics of the millet stem borer Coniesta ignefusalis (Hampson). Results confirmed that the main survival tactic employed by the insect was larval diapause, which lasts from November to May the following year. In both years, diapause termination occurred in the field 4-6 weeks after the resumption of the rains, depending on the year and location. Larval mortality rate was high during diapause with peaks occurring towards the end of the dry season in May. During the 2 years, larval populations declined by at least 50% between the start of diapause and its termination. No parasitoids were encountered during the study period, suggesting that biocontrol agents are probably not very important in the population dynamics of the insect. The implications of these findings for management of the pest are discussed.     

不同密度·揭膜时间和施氦量对免耕油菜生育动态的影响

1材料与方法 1．1试验地概况及品种 试验在贵州大学教学实验农场进行。试验地海拔1095m,年均气温15℃左右,土质为黄壤,肥力中等。供试油菜品种为贵杂4号。     

Decomposition characteristics of cotton stalks from fall to spring as affected by continuous cropping

Knowledge about cotton (Gossypium hirsutum L.) stalk degradation is important for understanding nutrient cycling in soil. The objective of this experiment was to study the effects of continuous cropping on cotton stalk decomposition and nutrient release patterns from fall to spring. Cotton stalks were placed inside nylon mesh bags on 5 October and then buried 15?cm deep in fields that had been continuously cropped to cotton for 1, 10, or 20 yrs. The results showed that the decomposition rates (i.e. mass loss) were significantly greater in the 10- and 20-yr soils than in the 1-yr soil during the first 16 d after burial. The decomposition rates were similar in all three soils between d 16 and 177. However, between d 177 and 193, the decomposition rates were the highest in the 1-yr soil. Overall, stalk mass declined by 35–40% during the 193 d experiment. The largest decreases in stalk mass were in the 1- and 10-yr soils. After 193 d, 95–97% of stalk K had been released compared with 29–34% of stalk P, and 41–48% of stalk N. The duration of continuous cropping had no significant effect on δ¹³C, N, and K release rates. The release rate of stalk P was the greatest in the 20-yr soil followed by the 1-year soil and then the 10-yr soil. In conclusion, the duration of continuous cotton cropping significantly affected the decomposition characteristics of cotton stalks. Additional studies will be done to learn more about how N application and irrigation can be managed in the fall so that (i) undecomposed residue does not interfere with spring sowing and (ii) the nutrients in the stalks are not lost after decomposition.     

亚麻受精过程及其经历的时间

应用石蜡制片技术, 观察亚麻的受精过程及其各阶段经历的时间。结果表明, 亚麻开花时落到柱头上的花粉随即萌发, 花粉管在花柱引导组织的细胞间隙中生长, 进入子房后经子房内表面, 沿胎座经珠柄进入珠孔, 进入1个助细胞, 在卵细胞与中央细胞之间释放2个精子;精子脱掉细胞质鞘后,形成精核与细胞质体;2个精核同时分别进入卵细胞和中央细胞, 并与卵核及次生核融合;精核与次生核融合速度稍快;观察到合子中雌、雄性核仁融合的过程。受精各阶段经历的时间为,花粉落到柱头上随即萌发;开花后4.5 h左右, 花粉管长入胚珠的珠孔;4.5~5.5 h,花粉管进入1个助细胞并释放精子;5.5~6.5 h为精卵融合和精核与次生核的融合期;7.5~8.5 h初生胚乳核分裂;12.5 h之后,合子分裂;6.5~12.5 h为合子静止期。     

高温对美国白蛾生长发育的影响研究

美国白蛾的卵、幼虫、蛹和成虫分别放在不同的温度处理下进行试验。研究结果表明：卵的孵化率、幼虫的存活率、蛹的羽化率、成虫的寿命均随着温度的增高而下降。高温脉冲对美国白蛾卵的孵化率和不同龄期幼虫的存活时间有显著影响。     

Effect of temperature and durations of heating on coir fibers

Biocomposites derived from polymeric resin and lignocellulosic fibers may be processed at temperatures ranging from 100 °C to 230 °C for durations of up to 30 min. These processing parameters normally lead to the degradation of the fiber's mechanical properties such as Young's modulus (E), ultimate tensile strength (UTS) and percentage elongation at break (%EB). In this study, the effect of processing temperature and duration of heating on the mechanical properties of coir fibers were examined by heating the fibers in an oven at 150 °C and 200 °C for 10, 20 and 30 min to simulate processing conditions. Degradation of mechanical properties was evaluated based on the tensile properties. It was observed that the UTS and %EB of heat treated fibers decreased by 1.17-44.00% and 15.28-81.93%, respectively, compared to untreated fibers. However, the stiffness or E of the fibers increased by 6.3-25.0%. Infra red spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) were used to elucidate further the influence of chemical, thermal and microstructural degradation on the resulting tensile properties of the fibers. The main chemical changes observed at 2922, 2851, 1733, 1651, 1460, 1421 and1370 cm⁻¹ absorption bands were attributed to oxidation, dehydration and depolymerization as well as volatization of the fiber components. These phenomena were also attributed to in the TGA, and in addition the TGA showed increased thermal stability of the heat treated coir fibers with reference to the untreated counterparts which was most probably due to increased recrystallization and cross linking. The microstructural features including microcracks, micropores, collapsed microfibrils and sort of cooled molten liquid observed on the surface of heat treated coir fibers from the scanning electron microscope (SEM) could not directly be linked to the effect of temperature and durations of heating although such features may have largely account for the lower tensile properties of heat treated coir fibers with reference to untreated ones.