Integrated assessment of adventitious rhizogenesis in Eucalyptus : root quality index and rooting dynamics

Clonal propagation of eucalypts has considerable importance due to the increasing demands for short rotation tree crops.Rooting quality is important as it governs the soil exploitation capacity of the plant and the anchorage of trees which are susceptible to wind damage.This study assesses the quality of adventitious rooting by coppice cuttings of commercially important Eucalyptus clones using multiple attribute ranking of the diff erences in parameters of root growth.The eff ects of diff erent concentrations of indole-3-butyric acid(IBA)on root development were observed.Cuttings were treated with 500,1000,4000,6000 mg L−1 IBA and tannic acid for 10 s,2 h and 24 h.Total length of root systems,number of roots,shoot to root ratios,number of root segments,extent of forking,rooting percentage,average root diameters,and number of root tips were measured.Grey relational analysis was used to create a comparability sequence to rank treatments.Reducing the concentration of auxin(IBA)and increasing the length of exposure produced better quality roots in Eucalyptus camaldulensis and interspecifi c hybrids(reciprocal hybrids of E.tereticornis and E.camaldulensis),while the opposite was observed with E.tereticornis clones.A root quality index was proposed,based on the Dickson quality index for the assessment of root system characteristics and considered total mass,shoot:root ratios,total length of root systems,and average root diameters.It has the advantage of implementation convenience.A positive correlation was obtained between grey relational analysis grades and root quality index.Rooting dynamics were studied by evaluating the total length of the root system at seven-day intervals and plotting daily current and medium increments using regression analysis.The curves showed the variation in growth rates among the diff erent clones,and their intersection gave the optimal time of permanence(time at which further growth is restricted)which varied considerably.The highest daily current increment was 35–40 days for all clones.

Compounding soils to improve cropland quality:A study based on field experiments and model simulations in the loess hilly-gully region,China

Increasing the quantity and improving the quality of cropland can alleviate the human-land contradiction and promote the sustainable development of agriculture especially in mountainous areas.With the support of the central government’s policies,Yan’an,Northern Shaanxi,China implemented a major land consolidation engineering project in the loess hilly-gully region from 2013 to 2018,achieving 33,333.3 ha of new cropland.However,the poor quality of some newly-constructed cropland at the initial stage hindered its efficient utilization.In order to overcome this problem,red clay and Malan loess were compounded in different volume ratios to explore the method to improve the cropland quality.The Root Zone Water Quality Model was used to simulate the effects of different soil treatments on soil water,nitrogen and maize growth.Experimental data were collected from 2018 to 2019 to calibrate and validate the model.The root mean square error(RMSE)of soil water content,nitrate nitrogen concentration,above-ground biomass,leaf area index were in the range of 11.72-14.06 mm,4.06-11.73 mg kg^(-1),835.21-1151.28 kg ha^(-1)and 0.24-0.47,respectively,while the agreement index(d)between measured and simulated values ranged from 0.70 to 0.96.It was showed that,compared with land constructed with Malan loess only(T1),the soil structure and hydraulic characteristics of land with a volume ratio of red clay and Malan loess of 2:1(T3)was better.Simulation indicated that,compared with T1,the soil water content and available water content of T3 increased by 14.4%and 19.0%,respectively,while N leaching decreased by 16.9%.The aboveground biomass and maize yield of T3 were 7.9%and 6.7%higher than that of T1,respectively.Furthermore,the water productivity and nitrogen use efficiency of T3 increased by 21.0%and 16.6%compared with that of T1.These results indicated that compounding red clay and Malan loess in an appropriate ratio was an effective method to improve soil quality.This study provides a technical idea and specific technical parameters for the construction or improvement of cropland in loess hilly-gully region,which may also provide reference for similar projects in other places.

Studies on Glutamine Synthetase Activity in Sugar Beet （BetavulgarisL．） under Different Levels of Nitrogen

It was shown from the experiment that glutamine synthetase activity (GSA) in both leaf blades and roots under different nitrogen levels rose rapidly to reach its peak from seedling stage to foliage rapid growth stage and declined to its lowest level at the latter stage of root rapid growth, and then increased slightly. GSA in leaf blades had positive correlation with nitrogen level during the whole period of growth. GSA in roots showed the same tendency as it in leaf blades at the early middle stage of growth, but at the latter stage of growth, no positive correlation was established. GSA in leaf blades was the strongest compared with crowns, petioles and roots, and could represent the highest enzyme activity of the whole plant. GSA had quadratic curvilinear correlation with root yield and sugar production. GSA in leaf blades had significant positive correlation with α-NH2-N at the foliage rapid growth stage.

Research on Glutamate Synthase Activity in Sugar Beet(Beta Vulgaris L.)under Different Levels of Nitrogen

The experiment of glutamate synthase activity (GOGATA) in both leaf blades and roots under different nitrogen levels was carried out at Northeast Agricultural University in 1993. The result showed that GOGATA rose rapidly to reach its peak from seedling stage to foliage rapid growth stage, and then declined gradually. GOGATA was enhanced with increasing nitrogen levels and had significant positive correlation with nitrogen levels at the middle stage of growth GOGATA in leaf blades was the strongest compared with crowns, petioles and roots, thus, it could represent the highest enzyme activity of the whole plant. GOGATA had quadratic curvilinear correlation with root yield and sugar production. GOGATA in leaf blades had significant positive correlation with α-NH 2-N at the foliage rapid growth stage while GOGATA in roots existed this relation at the latter stage of growth. GOGATA in roots had significant negative correlation with sugar content at harvest.

Fine root litter quality regulates soil carbon storage efficiency in subtropical forest soils

●High-quality and low-quality root litter had contrasting patterns of mass loss.●Greater litter-derived C was incorporated into soils under high-quality root litter.●Root litter decay rate or litter-derived C were related to soil microbial diversity.●Root litter quality had little effect on soil physicochemical properties.●High root litter quality was the main driver of enhanced soil C storage efficiency.Decomposing root litter is a major contributor to soil carbon(C)storage in forest soils.During decomposition,the quality of root litter could play a critical role in soil C storage.However,it is unclear whether root litter quality influences soil C storage efficiency.We conducted a two-year greenhouse decomposition experiment using 13C-labeled fine root litter of two tree species to investigate how root litter quality,represented by C to nitrogen(C/N)ratios,regulates decomposition and C storage efficiency in subtropical forest soils in China.‘High-quality’root litter(C/N ratio=26)decayed faster during the first year(0−410 days),whereas‘low-quality’root litter(C/N ratio=46)decomposed faster toward the end of the two-year period(598−767 days).However,over the two years of the study,mass loss from high-quality root litter(29.14±1.42%)was lower than‘low-quality’root litter(33.01±0.54%).Nonetheless,root litter C storage efficiency(i.e.,the ratio of new root litter-derived soil C to total mineralized root litter C)was significantly greater for high-quality root litter,with twice as much litter-derived C stored in soils compared to low-quality root litter at the end of the experiment.Root litter quality likely influenced soil C storage via changes in microbial diversity,as the decomposition of high-quality litter declined with increasing bacterial diversity,whereas the amount of litter-derived soil C from low-quality litter increased with fungal diversity.Our results thus reveal that root litter quality mediates decomposition and C storage in subtropical forest soils in China and future work should consider the links between root litter quality and soil microbial diversity.

Performance of pond–wetland complexes as a preliminary processor of drinking water sources

Shijiuyang Constructed Wetland（110 hm^2） is a drinking water source treatment wetland with primary structural units of ponds and plant-bed/ditch systems. The wetland can process about 250,000 tonnes of source water in the Xincheng River every day and supplies raw water for Shijiuyang Drinking Water Plant. Daily data for 28 months indicated that the major water quality indexes of source water had been improved by one grade. The percentage increase for dissolved oxygen and the removal rates of ammonia nitrogen, iron and manganese were 73.63%, 38.86%, 35.64%, and 22.14% respectively. The treatment performance weight of ponds and plant-bed/ditch systems was roughly equal but they treated different pollutants preferentially. Most water quality indexes had better treatment efficacy with increasing temperature and inlet concentrations. These results revealed that the pond–wetland complexes exhibited strong buffering capacity for source water quality improvement. The treatment cost of Shijiuyang Drinking Water Plant was reduced by about 30.3%. Regional rainfall significantly determined the external river water levels and adversely deteriorated the inlet water quality, thus suggesting that the ＂hidden＂ diffuse pollution in the multitudinous stream branches as well as their catchments should be the controlling emphases for river source water protection in the future. The combination of pond and plant-bed/ditch systems provides a successful paradigm for drinking water source pretreatment. Three other drinking water source treatment wetlands with ponds and plant-bed/ditch systems are in operation or construction in the stream networks of the Yangtze River Delta and more people will be benefited.

Software defect prevention based on human error theories

Software defect prevention is an important way to reduce the defect introduction rate.As the primary cause of software defects,human error can be the key to understanding and preventing software defects.This paper proposes a defect prevention approach based on human error mechanisms：DPe HE.The approach includes both knowledge and regulation training in human error prevention.Knowledge training provides programmers with explicit knowledge on why programmers commit errors,what kinds of errors tend to be committed under different circumstances,and how these errors can be prevented.Regulation training further helps programmers to promote the awareness and ability to prevent human errors through practice.The practice is facilitated by a problem solving checklist and a root cause identification checklist.This paper provides a systematic framework that integrates knowledge across disciplines,e.g.,cognitive science,software psychology and software engineering to defend against human errors in software development.Furthermore,we applied this approach in an international company at CMM Level 5 and a software development institution at CMM Level 1 in the Chinese Aviation Industry.The application cases show that the approach is feasible and effective in promoting developers＇ ability to prevent software defects,independent of process maturity levels.