Distribution,Etiology,Molecular Genetics and Management Perspectives of Northern Corn Leaf Blight of Maize(Zea mays L.)

Maize is cultivated extensively throughout the world and has the highest production among cereals.However,Northern corn leaf blight(NCLB)disease caused by Exherohilum turcicum,is the most devastating limiting factor of maize production.The disease causes immense losses to corn yield if it develops prior or during the tasseling and silking stages of crop development.It has a worldwide distribution and its development is favoured by cool to moderate temperatures with high relative humidity.The prevalence of the disease has increased in recent years and new races of the pathogen have been reported worldwide.The fungus E.turcicum is highly variable in nature.Though different management strategies have proved effective to reduce economic losses from NCLB,the development of varieties with resistance to E.turcicum is the most efficient and inexpensive way for disease management.Qualitative resistance for NCLB governed by Ht genes is a race-specific resistance which leads to a higher level of resistance.However,some Ht genes can easily become ineffective under the high pressure of virulent strains of the pathogen.Hence,it is imperative to understand and examine the consistency of the genomic locations of quantitative trait loci for resistance to NCLB in diverse maize populations.The breeding approaches for pyramiding resistant genes against E.turcicum in maize can impart NCLB resistance under high disease pressure environments.Furthermore,the genome editing approaches like CRISPR-cas9 and RNAi can also prove vital for developing NCLB resistant maize cultivars.As such this review delivers emphasis on the importance and current status of the disease,racial spectrum of the pathogen,genetic nature and breeding approaches for resistance and management strategies of the disease in a sustainable manner.

Sub-Surface Drip Irrigation in Associated with H_(2)O_(2) Improved the Productivity of Maize under Clay-Rich Soil of Adana, Turkey

Maize being sub-tropical crop is sensitive to water deficit during the early growth stages;particularly clay-rich soil,due to the compaction of the soil.It is well-documented that potential sub-surface drip irrigation(SDI)(Full irrigation;SDIFull(100%field capacity(FC)),Deficit irrigation;SDIDeficit(70%FC))improves water use efficiency,which leads to increased crop productivity;since it has a constraint that SDI excludes soil air around the root-zone during irrigation events,which alter the root function and crop performance.Additionally,in clay-rich soils,the root system of plants generally suffers the limitation of oxygen,particularly the temporal hypoxia,and occasionally from root anoxia;while SDI system accomplishes with the aerating stream of irrigation in the rhizosphere could provide oxygen root environment.The oxygen can be introduced into the irrigation stream of SDI through two ways:the venturi principle,or by using solutions of hydrogen peroxide through the air injection system.Therefore,the application of hydrogen peroxide(H_(2)O_(2);HP)can mitigate the adverse effect of soil compactness and also lead to improving the growth,yield and yield attributes of maize in clay-rich soil.Considering the burning issue,a field study was conducted in consecutive two seasons of 2017 and 2018;where hybrid maize was cultivated as a second crop,to evaluate the effect of liquid-injection of H_(2)O_(2)(HP)into the irrigation stream of SDI on the performance of maize in a clay-rich soil field of Adana,Turkey.When soil water content decreased in 50%of avail-able water,irrigation was performed.The amount of water applied to reach the soil water content to the field capacity is SDIFull(100%FC)and 70%FC of this water is SDIDeficit(70%FC).In the irrigation program,hydrogen peroxide(HP)was applied at intervals of 7 days on average according to available water with and without HP:SDIFull(100%FC)+0 ppm HP with full SDI irrigation;SDIFull(100%FC)+250 ppm HP with deficit SDI irrigation;SDIDeficit(70%FC)+0 ppm HP,SDIDeficit(70%FC)+250 ppm HP and SDIDeficit(70%FC)+500 ppm HP.Deficit irrigation(SDIDeficit(70%FC))program was started from tasseling stage and continued up to the physiological maturity stage with sub-soil drip irrigation.H_(2)O_(2) was applied 3 times during the growing season.Two years’results revealed that the liquid-injection of H_(2)O_(2) into the irrigation stream of SDI improved the growth and yield-related attributes and grain yield of maize.Based on the obtained results,during the extreme climatic condition in the year 2017,SDIFull(100%FC)+250 ppm HP was more effective than SDIFull(100%FC)+0 ppm HP on all traits for relative to full irrigation.While,during the favourable climatic condition in the 2018 season,SDIFull(100%FC)+250 ppm HP was more effective than full irrigation with SDIFull(100%FC)+0 ppm HP for the grain yield,grains,and SPAD value.Accordingly,the most effective treatment was SDIFull(100%FC)+250 ppm HP,as it gave the highest growth and yield-related attributes and grain yield of maize followed by SDIDeficit(70%FC)+250 ppm HP.Therefore,SDIFull with 250 ppm H_(2)O_(2) using as liquid-injection may be recommended to mitigate the adverse effect of soil compactness particularly water-deficit stress in clay-rich soil for the sustainability of maize production.