GLOBAL wheat growing areas. Temperature and relative humidity

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Last updated: September 2, 2019

GLOBAL THREATS TO CEREAL –AREVIEW           HABIB-UR-REHMAN 14-ARID-3041 SAHILNAZIR 14-ARID-3385      SHERAZ AHMAD 14 ARID 3395  Institute of Food and NutritionalScience PMAS Arid Agriculture University Rawalpindi            GLOBAL THREATS TO CEREAL–A RIVIEW                        HABIB-UR-REHMAN, SAHIL NAZIR                                      SHERAZ AHMADInstitute of Food and Nutritional Science PMAS AridAgriculture University Rawalpindi.Abstract Cereals are considered as the basic source of food and feedfor both human and animals respectively. Climatic factors like temperature ,moisture , rainfall , moisture and drought conditions can adversely effect thecereal crop yield. Different pathological factors and pests are also importantthreats for cereal crops. Crops are dependent on climatic conditions that’s whytheir yield and their physiological characters are effected.

The rapid increaseof the carbon di-oxide concentration in the atmosphere and related expectedrise of temperature can effect the functioning of ecosystems in future. Variousplants physiological processes are affected by climate change. The yield ofwheat , oat , barley and triticate is badly affected by bymoviruses andfuroviruses. These viruses and other pathogens are of great importance in wheatgrowing areas. Temperature and relative humidity and wind velocity interact innature and contribute collectively in making the environment favourable for thedisease development.

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However, all factors combine togather and cause differentdiseases to cereal crops that can reduce yield. KeywordsCereal ,Climate , Temperature ,Moisture, Diseases , Pests ,IntroductionThe rapid increase of the carbon di-oxide concentration inthe atmosphere and related expected rise of temperature can effect thefunctioning of ecosystems in future. Various plants physiological processes areaffected by climate change. CO2 increase stimulates photosynthesis and effectsstmatal conductance(Lemon 1983;cureand Acock 1986) and use of watereffeciancy(Gifford,1979).  Africa isdirected to climate change due to its long term dependence on rainfedagriculture(Belay,2013).

Small holder farmers are specifically exposed tochanges that badly effect their climate dependentlivelihoods(Ngigi,2009).Small-holder farming is affected by current climatechanges and will be more threatened by on going climate changes(Boko etal.,2007). Same as African countries ,Ethiopia also mainly dependent onagriculture, which help 50 percent to the national GDP, supplies 73 percent ofthe raw materials to agro industries and generates 88 percent of the expertearnings(Derssa and Hassan,2009).Ethiopian agriculture is characterized by aless use of external inputs and is highly exposed to climate changes(Demeke etal.

,2011). As like climate change ,Some diseases are also threat for Cerealcrops. Stripe rust(Yellow rust),  causedby Puccinia striiformis west, is a dangerous but sporadic disease of warmareas.

(Colin,2010). Small grain cereals , like wheat and barley are of outstanding importance of cropproduction. These crops are effected by diseases and affected by different kindof pests(Adams et al.,1988). The kernel bunt caused by Neovossia indica(Mitra)Mundkur(Mund-kur, 1940) was reported by Mitra in 1931 from kernel.

It isanother threat for cereal crops. Septoria disease is another threat for wheatcrop that was firstly reported in England and it is the risk factor for wheatcrop and it causes loss in yield(Barkeley ,1988).Soil borne viruses-a threatto cereal cropsA number offuro and bymo-viruses that are naturally transmitted by the ubiquitous soilborne protozoon polymyxa garminix areof great importance for wheat , oat , barley and triticate. The yield of wheat, oat , barley and triticate is badly affected by bymoviruses and furoviruses.These viruses and other pathogens are of great importance in wheat growingareas.

(Thomas,2009).Small grain cereals like Wheat and barley are and othercereal crops are attacked by viruses and numerous pests whickh causes manydiseases. (Table 1 ). In natural environment all  viruses are transmitted to their host plantby root inhabiting fungal like plasmodiophorid , polymyxa graminis.

(Adams et al.,1988). This microorganism isworldwide in distribution and multiplies in roots of grass and cereal species.

   Fungalprovides protection to viruses against unfavourable conditions and croprotation situation and allow virues to persist for long time.(Adams etal.,1993).

If the conditions are suitable and soil moisture is present thenthese viruses release zoospores which move actively towards host and enter roothairs cell.If the plant is affected then P.graminisacquires the viruses inside the cells(Camobell,1996). Table 1.Importantsoil borne viruses of cereals. Viruses species Acronym Genus Natural host species   W     B     T     R     O Barley yellow mosaic virus BaYMV Bymovirus           X Barley mild mosaic virus BaMMB Bymovirus           X Soil-borne wheat mosaic virus SBWMV Furovirus X       X     X     X Soil-borne cereal mosaic virus SBCMV Furovirus X       X     X     X Chinese wheat mosaic virus CWMV Furovirus X Wheat spindle streak mosaic virus WSSMV Bymovirus X              X     X Wheat yellow mosaic virus WYMV Bymovirus X Oat golden stripe virus OGSV Bymovirus                                 X Oat mosaic virus OMV Furovirus                                 X W=Wheat,B=Barley , T=Triticate , O=Oat , R=Rye Effect of weed on yield of Cereal crops.Wheat (Triticumaestivum L.) is the first and most important staple food in Pakistan and isadapted to wide range of soil and climate conditions.

Wheat plays a vital role inPakistan economic life. It is grown on an area of 8.3 million hectares with atotal production of 18.34 million tones in the world with average yield of 2166kg/ha (Govt of Pak.

1999) Pakistan is ranked 9 in wheat production. The averageyield of wheat in Pakistan is very low as compared to other wheat growingcountries of the world. Low  yield perhectare ,besides many other factors, may be attributed to serious weedinfestation.

Weeds lower crop productivity through their competition withcrop plants for nutrients, water, space, light and CO2.Weeds decrease yield by15-50 % and in serious cases may lead to the complete failure of crop (Gill andWalia, 1979). Besides their direct effect on crop, weeds also lower the marketvalue of the produce and hence bring enormous economic losses to growers.Effectof climate change on productivity of cerealsThe promt increase of the carbon di-oxide concentration inthe atmosphere and the related projected rise of temperature may affect thefunctioning of ecosystems in future. Various plant physiological processes areaffected by climatic variations. CO2 increase stimulates photosynthesis andeffect stumatal conductance(Lemon 1983) & Acock 1986) and water use efficiency(Gifford 1979). Field conditions varies in time and space , interactions withother environment factors occur, and species can vary in their response to CO2concentration(Sage et al., 1989).

Positive effect of CO2 and can compensate thenegative  effect of temperature(Kimball1983).Impact of moisture and temperature on the yield and qualityof wheat cultivars.Major step that decrease crop yield in the world is droughtreported by (Bruce et al,2002).

The combined effects of drought and hightemperature on the overall yield is higher that the individual effects  (Sharma and Kaurr,   2009, Grigorova et al.,  2011).Martell (2011) stated that Southern Europe Russia is the major wheat producingregion, in this area temperature and moisture stress cause premature ripeningof grain that cause significant reduce in yield.  Wang (2005) observed that moisture stress cause decrease in thephotosynthesis and accelerated leaf senescence that cause reduction in thewheat yield.

Temperature and relative humidity and wind velocity interactin nature and contribute collectively in making the environment favourable forthe disease development. However, all factors combine togather and causedifferent diseases to cereal crops that can reduce yield.Water stress under rainfed conditions significantly reducewheat grain yield (Hossain et al, 2012). Climate change cause changing inglobal rainfall patterns and increase in temperature influence the crop growthand yield Hasan-uz-Zaman et al, (2012).Hakim et al, (2012) reported thatoptimum temperature 20-25 C for spring wheat growth and yield. Changes in evapotransportation rate depend upon the availability of moisture at the onset of adrought and the severity and duration of a drought (Hanson,2003, Hossain et al,2012, Siapoosh et al., 2011).

 Table. 02Weather parameters during wheat growing season 2014-2015 atuniversity Research Farm Period day(from-To) Tmax Tmin Tavg. Precipitation      C   C    C     mm 2014/2015 Season         1st November-30th November 2014 26.41 9.36 17.

885 0 1st December-31st December 2014 23.8 5.39 14.586 0 1st January-31st January 2015 21.9 8.24 15.07 13.3 1st February -28th February 2015 29.

2 14.27 21.766 14.

5 1st March-31st March 2015 37.63 21.33 29.48 24 1st April-20th April 2015 39.84 22.52 31.18 76.36  Climate variability is a concern and researchers are engagedin understanding its impact on growth and yield of crops and also identifyingsuitable management options to sustain the crops  productivity under the rainfed ecology.

Climate variability may lead to prolonged dry spells or more intensified heatwaves seriously impairing agricultural productivity(hassan et al.,2013)Stripe rust impact on wheat cropProductivity with high yield is dependent upon resistances ortolerances in crop varieties. Thrust diseases of wheat have historically beenone of major biotic production constraints both in Pakistan and rest of theworld , in spite of enormous progress made iin their control in many countries. Stem rust , Leaf rust and stripe rust comtinue to pose a major threat toeheat production over a large area.(singh and Hassan , 2000).Of the three rusts diseases of bread wheat , stripe rust ismost damaging to grain yields(Singh et al.,2000).

Out of then total 8.803million of wheat production area in Pakistan , 70 percent is prone to striperust , which encompasses an area of about 5.8 million hactares. In Pakistan ,the rust epidemics have occurred in 1947-1948.

(Hassan et al.,1979).Stripe rust of wheat caused by puccinia striiformis f. a fungus belongs to order uredinals ofclass Basidiomycetes is one of the most important diseases of wheat and itsdistribution around the world were given by Hassebrauk(1965). Stripe rust ofwheat have been reported in more than 60 countries and on all continents exceptsAntarctica.(Gadd , 1777).Stripe rust cause 100 percent yield loss if infection occursvery early and the diseases continues to develop during the growing seasonprovided the cultivars are susceptible.

In most wheat producing areas , yieldlosses caused by stripe rust have ranged from 10-70 percent depending upon thesusceptibility of cultivars , earliness of initial infection , rate of diseasedevelopment and duration of the disease(Chen,2005).Resistance to yellow rust My be based on genes which areexpressed at all growth stages of the plant , or genes which are effectivemainly at the post seedling and adult plant stages where the level ofresistance increases as the plant matures(Johnson and Taylor,1972).Most stripe rust resistance genes have been mapped usinganeuploidy stocks(Mclntosh et al.,1995). But some was recently molecularlytagged. Depending upon the closeness of markers should be useful in markerassisted selection.

(yen et al.,2003).    TABLE 03.            ”A” GENOME BASED SH Seedling stage infection Type against yellow rust inoculums at CDRP sunny Bank Screen  house Murree NARC field screening Results to yellow rust inoculum 1           8-9           0 2           —-          — 3           —-          — 4           8-9          — 5           —-           0 6           2-3          30S 7           —-          — 8           5-6           0 9            7          — 10             7           0  S     =Susceptible         , —–= missing entriesDrought conditions in Pakistan  andimpact on cereal yield.

In Pakistan drought and high temperature can occur duringseedling emergence of wheat as well as grain filling stage. These stresses canbadly effect the seedling emergence , coleoptile length , seedling growth andphotosynthesis in wheat and other cereals crops. Drought effects morphological, physiological , biochemical and molecular processes in plants resulting ingrowth inhibition , stomatal closure with consecutive reduction of transpiration, decrease in chlorophyll content and inhibition of photosynthesis and proteinchanges(Demirevska , 2008). The world wide water shortage and un evendistribution of rainfall makes the improvement of drought resistance especiallyimportant. Fulfillment of this gaol would be enhanced by an understanding ofthe genetic and molecular basis of drought resistance(Bing et al.,2006).Drought stress is a major limitation to bread wheat productivity and its yieldstability in arid and semi arid regions of the world including parts ofPakistan. It has been estimated that about one third of the world’s potentiallyviable land suffers from an insufficient supply of water and crop yield areperiodically reduced by droght(Khan et al.

,2007).Drought is actually a meteorological event which implies theabsence of rainfall for  a period of time, long enough to cause mosture depletion in the soil and in water potential ofplant tissues. But from agricultural point of view, its working definitionwould be inadequacy  of water availability, including precipitation and soil-moisture capacity , in quantity anddistribution during the life cycle of a crop plant , which restricts theexpression of full genetic potential of the plant(Jiban, 2001).There are some varities of wheat that are resistance todrought.Table 04.Drought resistance index value Name of varieties Drought resistance index value Shafaq-2006                  0.515 AS-2002                  0.545 GA-2002                  0.

622 Inqalab-91                  0.604 Sehar-06                  0.522 Fareed-06                  0.515 Bhakkar-2002                  0.442 Auqab-2000                  0.580  Drought is a big problem for developing countries likePakistan , hindering the wheat production drastically.

  Impact of SITOTROGA CEREALELLA on the viability of wheat seed.A number of insect pests are responsible for the damage ofstored wheat grains like Rice weevil, lesser grain borer , Red flour beetle andAngumois grain moth.(Omer and Kamel,1984). These species damage the wheat andabout 2-6 percent food grain production is lost every year during storage bystored grain insect pests.

About 10-15 percent wheat is lost annually due toravages of stored grain insect pests during storage(Department of plant protection,1986).Khan et al.,(1985) investigated the storage losses to wheatin tehsil Faisalabad during a 10 months storage period in private  and public sector and public sector dodownsand found it to be 2.5 and 0.74 percent, respectively , resulting in overalllosses to wheat by insect pests during storage period from june to January.All stored grain insects posses the phenomenon of preferencefor then grains of various crops varirties.

This situation helps the plantbreeders to develop new varieties. This situation helps the plant breaders todevelop new varities which are less susceptible to attack of pests.(Sarin andsharma,1982).Table 05.Hatchability percentage of S. cerealella in different wheatvarieties. Variety hatchability percentage                 mean     R1                   R2                                      R3                 90   AUQAB-2000 91                  90                  89                 89   FSD-2008 88                  89                  90                 89.

3   INQALAB-91 90                  88                  90                 90   LASANI-2006 91                  90                  89                 90   BAKHAR 92                  90                  88                 90     IMPACT OF CEREAL APHID ON WHEATWheat is severely attacked by the wheat aphids which affectthe produce adversely (Grigorove,1976,).Greenbug,S GRAMINUM (Rondani) ismonoecious and exhibits life cycle on Graminae(Blackman and Eastop,  1984). This is prominent aphid speciesattacking in Pakistan.Bird cherry oat aphid,R. padi (Linnaeus) is heteroeciousmigrating between its primary host,the Bird cherry,prunus padus and itsGraminaceious host and exhibit holocyclic life cycle betweenthem(Naeem,1996).Corn leaf aphid can be found on corn,sorghum,wheat and barley.

English Grain Aphid can be found on corn , sorghum , wheat and barley. And theyare the emerging threat for cereal crops that reduce grain yield.(fitch,1993).Several control methods have been used to prevent losses byAphid. Host plant resistancenis an important part of IPM of aphids. Partialresistance could well provide adequate control of aphids with only cultural practices and occcasionaluse ofpesticide on out breaks.(Sattar et al.

,2001).Abiotic factors affect the physiology and behavior of insectsand acts as density independent factors which only determine the change ininsect population.abiotic factors can produce physiological effects on insectpopulation in four different ways by modifying activity of endocrine system ,survival , development and reproduction(Varley et al.,1973).Archer  et al.

,(1988)observed wheat response to Russian wheat aphid infestation varied at differentgrowth stages and determined the effects of wheat growth stages.      Table 06Correlation between Cereal aphid and population andagronomical characters of wheat varities. APHID Plant height Yield/10m2 Rhopalosiphum Padi Correlation   Significance         N -0.

255 NS     0.320    24 0.257 NS     0.226   24 Rhopalosiphum Maidis correlation   Significance       N -0.

137     0.523   24 0.162 NS     0.449   24 Schizaphis graminum Correlation   Significance            N 0.503     0.

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Australian Journal of Plant Physiology.6, 367-378. 

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