An integrated fertilization system of canola (Brassica napus L.) production under different crop rotations

Cropping systems in farmland areas of Iran are characterized by continuous cultivation of crops with consumption of chemical fertilizers leading to serious soil erosion and fertility decline. Information regarding the simultaneous evaluation of crop rotation and fertilization on the canola is lacking. Hence, field experiments were conducted during 2007-2010 using split-split plot design. Three crop rotations: chickpea, sunflower, wheat, and canola (R1); green manure, chickpea, green manure, wheat, green manure and canola (R2); canola, wheat, and canola (R3) were used as main plots. Sub plots were consisted of six methods of fertilization including (N1): farmyard manure (FYM); (N2): compost; (N3): chemical fertilizers; (N4): FYM + compost and (N5): FYM + compost + chemical fertilizers; and control (N6). Four levels of biofertilizers consisted of (B1): phosphate solubilizing bacteria (PSB); (B2): Trichoderma harzianum; (B3): PSB + T. harzianum; and (B4): without biofertilizers were arranged in the sub-sub plots. Results showed that green manure application in canola rotation (R2) increased grain yield and nutrient uptake. Combined application of FYM, compost and chemical fertilizers (N5) elevated the nitrogen uptake rate and grain oil yield. Simultaneous use of PSB and T. harzianum (B3) resulted in the increase of nitrogen and sulfur contents of grain. R2 rotation with regard to its biological and environmental efficiencies accompanied with FYM + compost and B3 (PSB + T. harzianum) is suggested as a low input system to obtain a more sustainable and productive farming in canola.     

Resistance to Peach-potato Aphid,Myzus persicae Sulzer (Hemiptera: Aphididae) in Potato Cultivars

Previous research suggests that potato cultivars offer little aphid resistance. However, few studies have measured the effects of host cultivar on aphid age dependent life table statistics or related these measures to field performance. In this study, laboratory and field studies assessed four commercial potato cultivars (Anya, Desiree, Pink Fir Apple, Santé) for resistance to Myzuspersicae. Cultivars were found to show considerable differences in resistance. In the laboratory, the intrinsic rate of increase (r_m) and effective fecundity of M. persicae was lowest on cv. Anya and highest on cv. Desiree. Aphids also took longer to develop to adults and were smaller in size on Anya compared with Desiree. Field studies over two seasons found that M. Persicae infestations started earlier on Desiree than on Anya and that the greatest weekly counts were recorded on the former.     

Exogenous Application of Glycinebetaine Modulates Activities of Antioxidants in Maize Plants Subjected to Salt Stress

The influence of exogenously applied glycinebetaine (0, 50 and 100 m m ) as a foliar spray at different growth stages, i.e. vegetative, reproductive or both at the vegetative and reproductive stages on gas exchange characteristics, glycinebetaine (GB) and the activities of antioxidant enzymes, such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) was examined in plants of two maize cultivars, Golden and C-20 grown under saline conditions. Salt stress caused a marked decrease in photosynthetic capacity, chlorophyll contents and SOD activity in both maize cultivars. However, activities of CAT and POD remained almost unchanged in both maize cultivars under salt stress. Accumulation of GB increased with an increase in exogenous level of GB, i.e. 100 m m GB spray caused a greater accumulation of GB in the leaves of maize plants than did 0 or 50 m m . Although exogenously applied GB enhanced photosynthetic capacity of salt-stressed plants of both cultivars, it enhanced the activities of antioxidant enzymes, SOD, CAT and POD, in salt-stressed plants of cv. C-20 only. Overall, the adverse effects of salt stress on maize plants were alleviated by the exogenous application of GB at different growth stages, which up-regulated photosynthetic capacity and the activities of some antioxidant enzymes.     

High-temperature mechanical properties and thermal recovery of balsa wood

This article presents an experimental study into thermal softening and thermal recovery of the compression strength properties of structural balsa wood (Ochroma pyramidale). Balsa is a core material used in sandwich composite structures for applications where fire is an ever-present risk, such as ships and buildings. This article investigates the thermal softening response of balsa with increasing temperature, and the thermal recovery behavior when softened balsa is cooled following heating. Exposure to elevated temperatures was limited to a short time (15 min), representative of a fire or postfire scenario. The compression strength of balsa decreased progressively with increasing temperature from 20° to 250°C. The degradation rates in the strength properties over this temperature range were similar in the axial and radial directions of the balsa grains. Thermogravimetric analysis revealed only small mass losses (<2%) in this temperature range. Environmental scanning electron microscopy showed minor physical changes to the wood grain structure from 190° to 250°C, with holes beginning to form in the cell wall at 250°C. The reduction in compression properties is attributed mostly to thermal viscous softening of the hemicellulose and lignin in the cell walls. Post-heating tests revealed that thermal softening up to 250°C is fully reversible when balsa is cooled to room temperature. When balsa is heated to 250°C or higher, the post-heating strength properties are reduced significantly by decomposition processes of all wood constituents, which irreversibly degrade the wood microstructure. This study revealed that the balsa core in sandwich composite structures must remain below 200°–250°C when exposed to fire to avoid permanent heat damage.     

Advances in studies on the physiological and molecular regulation of barley tillering

Tillering is a crucial trait closely associated with yield potential and environmental adaptation in cereal crops, regulated by the synergy of endogenous(genetic) and exogenous(environmental) factors. The physiological and molecular regulation of tillering has been intensively studied in rice and wheat. However, tillering research on barley is scarce. This review used the recent advances in bioinformatics to map all known and potential barley tiller development genes with their chromosomal genet...     

甘蓝型油菜种质群体油和蛋白质含量变异及相关性分析

本研究拟通过检测甘蓝型油菜种质群体种子的油含量和蛋白质含量及其二者之间的相关性分析,筛选出优异的育种资源,为甘蓝型油菜育种和基础研究提供材料。共检测了363份甘蓝型油菜种质群体种子,得出其油含量和蛋白质含量都表现出明显的变异,油含量、蛋白质含量及两者总含量的变异范围分别为27.9%~51.4%、20.8%~34.1%和57.8%~75.1%,并划分为3个群体。群体Ⅰ材料中,油含量和蛋白质含量分别为30.3%和31.6%,变异系数分别是5.3%与4.4%;群体Ⅱ材料中,油含量和蛋白质含量分别为39.6%和27.9%,变异系数分别是7.6%与6.5%;群体Ⅲ材料中,油含量和蛋白质含量分别为45.9%和23.8%,变异系数分别是4.4%与5.9%。相关性分析结果表明,材料的油含量和蛋白质含量都呈现出极显著负相关关系,其相关性系数r=-0.65(p<0.01)。通过本研究,筛选出了部分优异的种质材料,例如高油含量材料“林编12-71”和“浙油50”、高蛋白质含量材料“林编13-62”和“4 E 006”及高总含量(油+蛋白质)材料“林编12-230”和“AC 21”等。     

Understanding Interaction Patterns within Deep-Sea Microbial Communities and Their Potential Applications

Environmental microbes living in communities engage in complex interspecies interactions that are challenging to decipher. Nevertheless, the interactions provide the basis for shaping community structure and functioning, which is crucial for ecosystem service. In addition, microbial interactions facilitate specific adaptation and ecological evolution processes particularly essential for microbial communities dwelling in resource-limiting habitats, such as the deep oceans. Recent technological and knowledge advancements provide an opportunity for the study of interactions within complex microbial communities, such as those inhabiting deep-sea waters and sediments. The microbial interaction studies provide insights into developing new strategies for biotechnical applications. For example, cooperative microbial interactions drive the degradation of complex organic matter such as chitins and celluloses. Such microbiologically-driven biogeochemical processes stimulate creative designs in many applied sciences. Understanding the interaction processes and mechanisms provides the basis for the development of synthetic communities and consequently the achievement of specific community functions. Microbial community engineering has many application potentials, including the production of novel antibiotics, biofuels, and other valuable chemicals and biomaterials. It can also be developed into biotechniques for waste processing and environmental contaminant bioremediation. This review summarizes our current understanding of the microbial interaction mechanisms and emerging techniques for inferring interactions in deep-sea microbial communities, aiding in future biotechnological and therapeutic applications.     

Effect of tillage and fertilizer levels on wheat yield, nitrogen uptake and their correlation with carbon isotope discrimination under rainfed conditions in north-west Pakistan

Appropriate cultural practices need to be determined for enhancing crop yields with low inputs under rainfed conditions. A field experiment was conducted to study the effect of tillage practices and fertilizer levels on yield, nitrogen (N) uptake and carbon (C) isotope discrimination in wheat (Triticum aestivum L.) grown under semi-arid conditions at three sites in north-west Pakistan: NIFA, Urmar and Jalozai. Two fertilizer levels, 60 kg N ha⁻¹+30 kg P ha⁻¹ (L1) and 60 kg N ha⁻¹+60 kg P ha⁻¹ (L2), were applied to wheat grown under conventional tillage (T1) and no-tillage (T0) practices. Labeled urea having 1% ¹⁵N atom excess at 60 kg N ha⁻¹ was applied as aqueous solution in microplots within each treatment plot. A pre-sowing irrigation of 60 mm was applied and during the growing season, the crop relied entirely on rainfall (268 mm). Biomass yield, N uptake and stable C isotope composition (δ¹³C) of plants were determined at maturity. Yield of wheat was improved by tillage at two sites (Sites 1 and 2), while at the third site yield was reduced by tillage as compared with the no-tillage treatment. At Sites 1 and 2, nutrient addition (L2, 60 kg N ha⁻¹+60 kg P ha⁻¹) increased the yield of all plant parts (straw, grain and root) in contrast to Site 3 where only grain yield was increased significantly. Maximum grain yield of wheat was observed with tillage under nutrient level L2 at all sites. Generally, the tillage treatment did not affect the N content in plant parts compared with no-tillage (T0) treatment at all three sites. However, fertilizer N uptake by wheat was variable under different fertilizer levels and tillage practices. Nitrogen derived from fertilizer (Ndff) for grain at Site 2 was higher in tilled plots but was not affected by tillage practice at the other sites. The C isotope (δ¹³C) values varied from −28.96 to −26.03‰ under different treatments at the three sites. The δ¹³C values were less negative indicating more effective water use at Sites 2 and 3 compared to Site 1. The C isotope discrimination (Δ) values were positively correlated with yield of wheat straw (r=0.578^*), grain (r=0.951^**) and root (r=0.583^*). Further, the Δ in grain had significant negative relationship (r=0.912^**) with Ndff (%). The tillage practice exerted a positive effect on yield, N uptake and plant N derived from fertilizer by wheat compared to no-tillage. The positive correlation of Δ with grain, straw and root yields and negative correlation with the Ndff (%) by wheat suggest that this value (Δ) could be used to predict these parameters. However, further studies on different crops under varied environmental conditions are necessary.     

Devaluating Drainage Design Parameters for the Fourth Drainage Project, Pakistan by using SWAP Model: Part I – Calibration

A transient drainage simulation model,SWAP, was used to evaluate the performanceof drainage systems in (semi-) arid zones.Before application, the model wascalibrated by using 14-months datacollected from two sample fields of theFourth Drainage Project (FDP), Punjab,Pakistan. During the calibration process,emphasis was given to the accuratedetermination of soil hydraulic parameters,reference evapotranspiration, drainage fromsample fields and bottom boundarycondition. Laboratory determined soilhydraulic parameters were foundnon-representative of the field conditions.Difference between laboratory and fielddetermined soil water retention curves werefound significant. The pressure heads andsoil water contents measured in depthincrements of 15 cm were in good agreementwith the simulated values after applying afield measured retention curve. A closeproximity was also found between measuredand simulated average root zone salinity at0–1.0 m depth. The referenceevapotranspiration calculated by thePriestly-Taylor (PT-ET _o) methodwas found physically more realistic thanthe Penman-Monteith (PM-ET _o)method due to ignorance of the feed backmechanism of vapor pressure deficit onstomatal closure. The simulated cumulativedrainage from two sample fields wascomparable with the calculated values. Theanalysis of piezometer data shows thatthere is a negligible water exchangebetween the deep aquifer and theunsaturated zone. Therefore for scenarioanalysis, no flow conditions at the bottomof the soil profile can be applied as abottom boundary.     

Synergetic use of biochar and synthetic nitrogen and phosphorus fertilizers to improves maize productivity and nutrient retention in loamy soil

Abstract

This study was designed to investigate the effect of biochar on maize production and nutrient retention with recommended full and half dose of nitrogen (N) and phosphorus (P) nutrition in loamy soil. In the first study, maize was grown in pots with four levels of biochar (0, 2, 4, and 6?t?ha^?1) under two levels of NP fertilizer, viz. recommended (200–150?kg?NP?ha^?1) and it’s half (100–75?kg?NP?ha^?1) dose. The prominent improvement in plant roots traits, leaf area, plant growth, morphological and yield-related parameters were observed with addition of biochar at 2 and 4?t?ha^?1; while, plant height, number of grains per cob, grains and biological yield decreased with biochar addition 6?t?ha^?1 along with full dose of NP nutrition. In subsequent field studies, two levels of biochar along with control (0, 2, 4?t?ha^?1) were investigated. The more improvement in root growth, leaf area and crop growth was observed when biochar was applied at 2?t?ha^?1 with full NP nutrition. Biochar application at 2?t?ha^?1 with full NP nutrition produced the highest grain yield (6.64?t?ha^?1); however, biochar addition (2?t?ha^?1) with half NP nutrition resulted in better grain yield than full dose of NP to enhance maize production as compared with full dose of NP without biochar. Therefore, biochar addition (2?t?ha^?1) with half-recommended dose of NP prominently improved the maize productivity in loamy soil and serve as better in replacement of full dose of NP fertilizer.