Soil nitrogen availability under grassland and cultivated corn

Summary Adjacent corn and ryegrass plots were fertilized with rates of 0, 50, 100, 150, and 200 kg N as ammonium nitrate/ha. Corn growing on this soil did not respond to fertilizer N while ryegrass responded to rates of up to 200 kg N/ha. The differences in N availability was also reflected in the higher profile NO₃–N under corn than under ryegrass. The same general trends occurred on a second soil, where N availability for the hay crop was also less than for corn crop. Compared with corn, hay responded more to N fertilizer and had lower soil NO₃–N levels.Grasslands appear to respond to higher N fertilizer rates than cultivated crops on the same soil.Vermont Agricultural Experiment Station Journal Article No. 495.     

Control of Fusarium verticillioides on corn with a combination of Bacillus subtilis TM3 formulation and botanical pesticides

The aim of this study was to evaluate the effectiveness of the combination of Bacillus subtilis TM3 formulation with botanical pesticides in suppressing Fusarium verticilloides infection in corn. The research was carried out at the Plant Pathology Laboratory and the Experimental Farm of Indonesian Cereals Research Institute (ICERI) from February to November 2019. The research consisted of two stages, namely an in vitro test of antagonists of botanical pesticides against F. verticilloides using 5 types of plant extracts namely betel leaf extract, turmeric, galangal, cosmos, and clove leaf. The second stage was to test the effectiveness of the combination of the formulation of B. subtilis TM3 with the best 3 types of plant extracts in vitro testing in suppressing F. verticilloides infection in plants. The results of the in vitro study showed that the plant extracts of betel leaf, clove leaf and galangal had the best inhibitory ability on the mycelia growth of F. verticilloides. Meanwhile, the field test found that the application of the B. subtilis TM3 formulation, either alone or in combination with plant extracts, was able to suppress F. verticilloides infection. The combination of B. subtilis TM3 formulation with betel leaf extract showed the best inhibition of 20% against stem rot disease and 13.33% against corn cob rot. This treatment did not affect production quantitatively, but was able to suppress the decline in seed quality due to F. verticilloides infection. Seeds grown by the Plastic Rolled Paper Test (PRPT) method were not only infected with F. verticilloides, but also infected with other seed-borne pathogens, such as Aspergillus niger and A. falvus. The presence of these two pathogens did not inhibit the growth of F. verticilloides in kernels.     

Degradation of leaf polar lipids during chilling and post-chilling rewarming of Zea mays genotypes reflects differences in their response to chilling stress. The role of galactolipase

Degradation of leaf polar lipids [monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinovosyldiacylglycerol (SQDG) and phosphatidylglycerol (PG)] and chlorophyll (Chl) were studied in four Zea mays genotypes differing in chilling susceptibility following dark chilling and post-chilling rewarming at original growth conditions. Assessment of visual chilling injury symptoms during post-chilling rewarming differentiated maize inbred lines into chiling-sensitive (CS) CM7 and Co151 lines and chillingtolerant (CT) S215 and EP1 lines. Severity of chilling injury in CS and CT inbreeds were correlated with the extent of Chl and polar lipids degradation. Chilling for either 4 or 6 days followed by 4 days of rewarming caused more extensive degradation of total polar lipids content in CS than in CT lines. MGDG decreased mostly during chilling whereas DGDG dropped during rewarming only. Chl content was not affected during chilling but its large decrease, greater in CS than in CT lines, was observed upon rewarming. Extent of polar lipids breakdown in CS and CT inbreeds during chilling and post-chilling rewarming is correlated with galactolipase activity in chloroplasts (Kaniuga et al., 1998) and visual assessment of chilling injury. In view of the data it is likely that contribution of galactolipase activity induced during low-temperature stress of CS plants is an important factor responsible for thylakoid lipid degradation and development of chilling injury as postulated previously (Kaniuga 1997). It is suggested that genetically engineered reduction of galactolipase activity or elimination of the factors(s) involved in induction/stimulation of its activity during chilling might increase tolerance of CS species to chilling stress.     

螟长距茧蜂、玉米螟与春玉米间相互关系的初步研究

研究表明,螟长距茧蜂发生高峰期比玉米螟成虫高峰期大约推迟6-9天,与春玉米抽雄期相一致。玉米抽雄开花时绝大部分玉米螟幼虫处在易被螟长距茧蜂寄生的Ⅲ、Ⅳ龄。玉米开花后雄穗的形态结构和营养成分发生改变,致使幼虫下垂转移寻找更适宜的食物。螟长距茧蜂被取食玉米雄穗的玉米螟幼虫所吸引。其寄生与玉米螟幼虫的发育和玉米生育期密切相关。     

盐胁迫下丛枝菌根真菌对玉米水分和养分状况的影响

在ＮａＣｌ胁迫下无论接种ＡＭ真菌与否玉米植株生物产量均减少,但不接种处理的减少幅度比较种处理的高１０个百分点左右,盐胁迫下接种ＡＭ真菌的玉米根系和地上部的干重、叶片水热均高于不接种处理、叶片脯氨酸含量低于不接种处理,在盐胁迫下真菌菌丝对玉米植株营养的贡献由４５．３％降为４２．６％,ＡＭ真菌对植株生长的效应反而由３０．９％提高到６３．５％,说明ＡＭ真菌主米耐盐性的机理与改善植株的水分状况和Ｐ营养状况     

Growing degree days – Ecosystem indicator for changing diurnal temperatures and their impact on corn growth stages in Kansas

Understanding how climate change will affect plant phenology (shifts in the timing of plant activity) is central to many ecological and biogeochemical studies. This aspect of plant ecology often has been overlooked, but addressing the consequences of climate change for adaptive/mitigative management is now high on the list of priorities for funding agencies. This study is innovative because it uses growing degree days (GDD), which has existed since the 1730s, as an ecosystem indicator to study changing diurnal temperatures; their effects on different plant growth stages in the last century; and as a basis for development of future adaptive management strategies. Our results show the most recent time period (1980–2009) had the earliest emergence and the least variability among stations in the day at which the crop stage occurred for most stages except emergence and physiological maturity. 100 year linear trends in the stations indicated all seven crop stages except tassel initiation occurred earlier by one day per decade during the study period. The number of stations with significant decreases varied from 11 to 17 stations out of 23 stations in Kansas. Tassel initiation stage occurred later by one day per decade during the study period. The most recent time period (1980–2009) had the highest variability among stations and 30 year time periods. The variability in trends is higher in western Kansas when compared to eastern Kansas. This knowledge has transformative potential to improve our understanding of the occurrence and duration of the different plant growth stages, add local precision to earlier findings for changes in overall GDD that encompassed larger areas, and help explain the differences in trends from some earlier studies. These shifts in the phenology of agricultural plants as a result of climate change have implications on food production increases required to feed the growing population.     

Effects of corn steep liquor on production of 2,3-butanediol and acetoin by Bacillus subtilis

The initial concentration of corn steep liquor (CSL) have remarkable effects on not only 2,3-butanediol (2,3-BD) and acetoin (metabolic precursor) production, but also on the ratio of 2,3-BD to acetoin. When a high concentration of CSL was supplemented, cell growth was improved, acetoin reductase (ACR) was stimulated, the concentration of 2,3-BD increased by 78.6%, acetoin decreased by 61.9%, and the ratio of 2,3-BD to acetoin increased by 3.69-fold. The acr gene, encoding ACR, was over-expressed in Bacillus subtilis. Compared to the control (parent strain), low levels of CSL in the engineered strain increased 2,3-BD concentration and the ratio 2,3-BD to acetoin by 13.9% and 39.5%, respectively, and decreased acetoin titer by 18.3%. Acetoin became a major product under low levels of CSL. Also, a knockout strain carrying an acr::cat insertion mutation was constructed. As expected, the loss of ACR activity led to an accumulation of acetoin in the supernatants of acr:: cat mutant cultures. Additionally, the productivity of acetoin was improved by high concentration of CSL. The results above demonstrate the feasibility of using B. subtilis for the production of not only 2,3-BD but also acetoin as a major product.     

Optimization of conditions for the production of lignocellulolytic enzymes by Sphingobacterium sp. ksn-11 utilizing agro-wastes under submerged condition

Abstract

The present work was aimed at studying the production of lignocellulolytic enzymes, namely cellulase, xylanase, pectinase, mannanase, and laccase by a newly isolated bacterium Sphingobacterium sp. ksn-11, utilizing various agro-residues as a substrate under submerged conditions. The production of lignocellulolytic enzymes was found to be maximum at the loading of 10%(w/v) agro-residues. The enzyme secretion was enhanced by two-fold at 2?mM CaCO_3, optimum pH 7, and temperature 40°. The Field Emission Gun-Scanning Electron Microscope (FEG-SEM) results have shown the degradative effect of lignocellulases; cellulase, xylanase, mannanase, pectinase, and laccase on corn husk with 3.55?U/ml, 79.22?U/ml, 12.43?U/ml, 64.66?U/ml, and 21.12?U/ml of activity, respectively. The hydrolyzed corn husk found to be good adsorbent for polyphenols released during hydrolysis of corn husk providing suitable conditions for stability of lignocellulases. Sphingobacterium sp. ksn is proved to be a promising candidate for lignocellulolytic enzymes in view of demand for enzymes in the biofuel industry.     

Fractal kinetic analysis of the enzymatic saccharification of CO2 laser pretreated corn stover

The enzymatic hydrolyses of laser pretreated corn stover as a novel pretreatment method were examined to establish a simplified kinetic model for the complicated hydrolysis process. The time dependence of the total reducing sugars amount was closely related to the amounts of cellulosic materials and amounts of cellulase. The evaluated model fitted very well with the experimental data of enzymatic hydrolysis of laser pretreated corn stover under different conditions, including cellulase loading, nature of substrate, substrate loading in the reaction medium. The results indicated that the complex kinetics of cellulase enzymatic saccharification could be assessed with the fractal kinetic model. The cellulase enzymatic reaction process was effectively predicted and controlled with the kinetic model. The result showed that the model could effectively reflect dynamic process of enzyme hydrolysis.     

Valorization of corn cob for the obtention and purification of endoglucanase produced by SSF

Agro-food by-products contain valuable nutrients which are wasted. In this work, solid-state fermentation (SSF) was carried out using corn cob as substrate for endoglucanase production. The radial growth of three fungal strains -Trichoderma harzianum T104, Aspergillus niger GH1 and Aspergillus niger NRRL3- was analyzed in order to select the most appropriate. Radial growth data were analyzed with a mixed linear model for longitudinal data and no statistically significant differences were found between both A. niger strains.Endoglucanase was separated from the extract of A. niger GH1 by fast protein liquid chromatography (FPLC).The highest endoglucanase activity was detected in fraction number three collected from FPLC corresponding to 72 h of SSF. Seven bands in a range from 24 to 50 kDa, which correspond to endoglucanase from fungal extract, were detected by zymogram analysis. According to protein quantification performed by the ImageJ software, 85% of the proteins present in the samples collected by FPLC corresponded to endoglucanase proteins. The purified endoglucanase retained about 100% of its catalytic activity at 30 °C and 50 °C and was stable in a pH range between 4.00-6.00. These properties make this isolated enzyme suitable for industrial applications such as the saccharification process for bioethanol production.