CROP ECOLOGY AND MORPHOLOGY
CROP ECOLOGY AND MORPHOLOGY CSS 200
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V CSS 200 Crop Ecology and Morphology Oregon State n Stability and Diversity 0 Stability is the degree of variation in crop yield over time at a particular location 0 Variation in yield can occur because of weather eld history production potential spatial uniformity weeds insects diseases etc The price of the crop and variation in costs can affect yield Farmers tend to Combine and grain truck in wheat field cut back on inputs when costs are high and prices are low resulting in lower yields When prices are high production can expand onto fields with lower production potential and into poorer environments thereby reducing stability of crop yield Hillside combine operating on very steep slope Technology can both increase and decrease stability in some instances For example improvements in farm machinery permits farming in environments that are not optimum for production of a particular crop resulting in less stability Drainage in wet elds not only increases yield but also reduces variation in yield thereby increasing stability Crop improvement through breeding increases yield and can reduce variation in yield Yield Variation Yield Variation 100 75 50 25 Resource insensitive crop slope dYdx O 100 75 50 25 0 25 50 75 100 Resource sensitive crop slope dYdx gt O O 25 50 75 Resource Level Yield can vary over time as a result of the sensitivity of the crop to the level of resources provided to the crop In the top example the crop is not sensitive to resource level The slope defines the sensitivity of the crop to resource levels such as nutrients water etc The resource level does not affect the variation in crop yield In the bottom example yield variation is minimized when the critical resource is supplied to the crop When crops are grown outside optimum climatic conditions small variations in environment or management can cause large variations in yield Genetic I r 6 Potentlal 39 I Q 397 539 u g a EL 1 4 r 1 5quot 3 y g 9 107 0068X1930 000064X19302 r2 094 39lt 396 I I n I I n I n I I I 1 a I n n n I n I n I Inn I 1 93930 193940 193950 193960 193970 193980 1950 Ygal 39 4 Yield of Maize Cultivars I 3 1 1930 1940 391 f Introducsion vi a 41 3 g a 950 1960 1970 1980 1990 Yero Grain Yield kgha Grain Yield kgha 5000 4000 3000 2000 1000 3000 2000 1000 187018801910193019401950196019701980 Year of Cultivar Release Increased yield stability can be attained through genetic improvement of crop cultivars Genes for disease resistance and drought tolerance increase yield under adverse conditions thereby improving yield stability The graphs illustrate the contribution of genetic improvement to grain yield of soft red Winter Wheat in Ohio top and hard red Winter Wheat in Kansas bottom Cultivars released over the past 110 years were grown together under uniform management Genetic improvement of grain yield in soft red winter wheat top and in hard red winter wheat bottom Wheat yield along a transect across Oregon counties Yamhill Sherman Umatilla Union healsA 0 Wheat y1eld var1es w1th precipitation across Oregon The differences in rainfall affects crop yield stability 78 bushelsA 43 bushelsA 60 bushelsA 65 bus Yield BuAcre Variation in wheat yield over time in selected Oregon counties 120 100 80 60 40 20 Sherman IUmatilla Union Yamhill 1980 1985 1990 1995 2000 Year so 7 406 i 00 SD I i L96 SD Frequency 2 l i i i 257 SD i 0 4 8 Yield level t haquot Variability in crop yields over time The variation in crop yield over time in a location stability can be measured by using the Coef cient of Variation CV Need to know the standard deviation SD of the mean and the mean yield over time to calculate the CV SD CV T Y Where CV coefficient of variation SD standard deviation Y mean crop yield Wheat yield along a transect across Oregon counties Yamhill Sherman Umatilla Union 78 bushelsA 43 bushelsA 60 bushelsA 65 bushelsA For Sherman county n lt II U1 lt O 946 022 4288 Other CVs are Yamhill 015 Umatilla 019 Union 021 A large CV is indicative of low stability in crop yield whereas a small CV represents high stability Seed Yield lbsacre Stability of Willamette Valley grass seed crop yield 1600 1400 1200 1000 800 600 400 200 I C V Chewings F escue Perennial Ryegrass Tall Fescue 1975 1980 1985 1990 Year I 1995 2000 Multiple cropping of banana and cassava Some feel that species diversity is essential for achieving stability in crop production systems However there is little evidence that diversity is an important basis for community stability in natural systems and even less evidence in humanmanaged cropping systems Multiple cropping systems usually have more variation in yield not less and eXhibit less stability than monoculture systems as well as more risk Yield c haquot Soybean l Illinois Diversity is an important factor in risk reduction in cropping systems when crops are rotated The risk of economic losses resulting from catastrophic crop failure are lessened When a greater diversity of crops are grown in an agricultural system V CSS 200 Crop Ecology and Morphology I Oregon State n Energy and Cropping Systems The energy supply and economic security of a nation are inextricably linked Our nation s energy supply was threatened in the 1970s by world events but the underlying factors for that disruption have not changed A reliable supply of energy is required to support modern mechanized agriculture and associated processing industries The need for alternative energy sources is selfevident Vehicles lined up for gas in the 19705 Oil Price barrel 125 100 75 50 25 1980 1990 2000 2010 Year Energy supply and farm pro ts are also linked Rising fuel costs reduce the pro tability of farming enterprises Farmers are large consumers of diesel fuel and other fuels Pro t Profit cost Cost Low fuel prices High fuel prices Corn crop canopy top solar panels bottom Agriculture is energy farming 7 even the grass seed that we grow here has energy stored inside A crop canopy captures solar energy much like solar panels but very much more ef cient in energy capture Growing a crop is all about making the best possible solar energy harvesting system The solar energy from agriculture is stored as chemical energy in products ranging from starch in a crop seed to beef Chemical Energy Content of Common Materials Material Sugar Wood Protein Coal Ethanol Natural Gas Plant Oil Diesel Gasoline Energy content MJlb 7 9 11 11 13 16 18 20 20 Various materials have differing energy content 7 petroleum products have very high energy content Wood averages 9 MJ energy per pound of wood combusted in a fire Energy Budget for Corn Production Energy Input MJ hectare Labor 280 Machinery 366 Diesel Fuel 2104 Gasoline Fuel 1136 Nitrogen Fertilizer 13000 Phosphorus Fertilizer 1097 Potassium Fertilizer 1076 Seed 384 Herbicide 1314 Fuel for Drying 2607 Electricity for Drying 86 Total Inputs 23500 Output Corn yield 88tha 146800 The energy required for crop production can be illustrated by using an energy budget Energy for tillage fertilizers harvest and other crop production activities are outlined in the budget Even the energy used in producing the seed and in manufacturing the machinery are determined in this lifecycle budget Not that the energy output for crop production capturing solar energy and converting it to a harvested corn crop far exceeds the energy used to produce the crop Index 1996 10 1948 1954 1960 1966 1972 1978 1984 1990 1996 2002 Year Energy conservation and ef ciency on the farm The energy required for crop production can be reduced through conservation and improved ef ciency As the cost of energy has increased the amount of energy used by farmers to produce crops has declined Energyconserving notill drill top near Corvallis Farm energy use per unit of farm output bottom Persons fed per US farmer 140 Growing fuels for agriculture 120 39 Prior to the advent of mechanized 100 agriculture farins produced much 80 of the their energy needs on the 60 farin Some of the increase in agricultural 40 productivity can be attributed to the 20 import of fuel from outside the 0 I I I I I I I farming operation Growing crops 1930 1940 1950 1960 1970 1980 1990 2000 for biOfUCIS W0111d 106mlit fanners Year to regain a stake in their own energy production The questions are Can we grow our own fuels and can we grow enough Does it make sense to grow our own fuels Energy and Cropping Systems US Dept of Energy photo 1 u c 1 us Energy Use I Natural Gas Lnerb and CH l Nuclear 237 l Renewables D l Coal l Petroleum 39 8 397 23 Gallons millions US Ethan0l PFOdUCtiOn US Biodiesel Production 7000 500 6000 E 400 5000 9 4000 E 300 3000 g 200 2000 r ts 1000 0 10 39 0 0 39l39 1980 1990 2000 2010 2000 2002 2004 2006 2008 Year Year Fuel Yields for Various Feedstock Crops Note Biodiesel energy is 34 MJliter while Ethanol energy is 21MJliter Su garca ne 2000 4000 6000 8000 Outputinput ratio 83 Macedo et al 2003 Energy Balance If crops are to be used as feedstocks for the production of biofuels then the energy required for crop production and fuel processing must be less than the energy derived from the biofuel Energy Balance Fuel Energy Value Production Processing Energy Corntoethanol Energy Balance Outputinput Energy Study Authors Balance Ho 1989 096 Marland and Turnhollow 1990 125 Pimentel 1991 075 Keeney and DeLuca 1992 093 Shapouri et al 1995 119 Lorenz and Morris 1995 137 Wang et al 1999 133 AgriFood Canada 1999 132 Pimentel 2001 075 Wang NREL 167 Celluloseto Ethanol Energy Balance Outputinput Study Authors Feedstock Energy Balance Wang 2001 Grass 073 Wood 066 GMANL 2001 Grass 063100 Wood 053077 Levelton 2000 Grass 078 Corn residue 091 Hay 076 Wheat Straw 089 GM et al 2002 Wood 083 USDA 2006 Various 262 Biodiesel Energy Balance Outputinput Study Authors Feedstock Energy Balance McIntosh et al 1983 Sunflower 261 269 Safflower 216230 Canola 421 Levy 1993 Rapeseed 175192 Altener 1996 Rapeseed 182244 NREL 1998 Soybean 320 Levington Rapeseed 250 GM et al 2002 Rapeseed 303 Pimentel and Patzek Soybean 098 2005 Sunflower seed Biodiesel Energy Production l 3100 lbs canola seedacre 163 gallons biodiesel 1900 lbs meal Canola seed left and 39 7 crusher I 7 right 39 l 19 lbs seed 1 gallon oil Biodiesel Energy Production vAv 39 Canola Agriculture Canola Processing Energy needed to grow one Energy needed to crush seed and acre of canola 8432 MJ process oil into biodiesel 1225 MJ Biodiesel Energy Production A 4 lt0 5 7 A Canola Agriculture Canola Processing Energy from biodiesel 22427 MJ Energy from canola meal 19322 MJ Total Energy 41749 MJ 41 Energy Ratio Net Energy Balance 32092 MJ Energy Balance of Potential Oregon Biofuel Crops Source Oil Yield Energy Ratio Gallonsacre Gallonzgallon Canola biodiesel 100200 421 Soybean biodiesel 1525 57 US average 321 Sunflower biodiesel 90100 261 Corn ethanol 171 Petroleum 081 V CSS 200 Crop Ecology and Morphology Oregon State n The Edaphic Factor 11 OM o 35 30 1881 WheatFallow Conventional Tillage Pendleton Oregon 0 to 30cm soil depth 139 I 10 ta391 of manure n 40 lba391 of N o o Iba391 of N o 0 lba391 of N residue burned 1901 1921 1941 1961 YEAR I 1981 Organic matter and crop productivity Crop productivity is closely associated with the organic matter of the soil Farming practices such as fallow and tillage cause a decline in organic matter over time from the levels originally observed in the natural environment The Edaphic Factor Plant macronutrients source and form Nutrient Source Available Form Hydrogen Water in soil H20 Carbon Air CO2 Oxygen Air and Soil 02 Nitrogen Soil Organic and Inorganic Air NH4 N03 The Edaphic Factor g 39 39h d 39 I ea c g 160 lomtmg emergence Perennial ryegrass 120 g Tall fescue 2 so o 2 3 4 39 39 E 8 O 1 I I I 41 51 61 71 Month and Day Spike Number no m39z 500 400 W 300 200 e o More v Pendleton 100 0 0 20 40 60 80 Applied N kg ha39l 100 Grain Yield kg ha39l The Edaphic Factor Effect of N fertilizer on winter wheat yield over 4 years at Moro and Pendleton 6000 5000 4000 3000 2000 1000 O Moro v Pendleton 0 20 40 60 80 Applied N kg ha39l 100 Fall N and Spring N application effects on seed yield in tall fescue Young et al 2004 Spring N rates 120 lbsacre 160 0 I I 0 40 80 120 Fall N lbsacre 1200 E 1000 U U 3 800 B 2 600 G 390 40 g 200 80 V Generalized Crop Response to Nutrient Availability I00 1 0 Growth o of maximum L Adequate J Critical Zone reduced yieid I without deficiency symptoms I I lt 39 Inadequate deficiency symptoms I present I I 4 Critical Nutrient Concentration I Relative Tissue Nutrient Concentration Plant Nitrogen Metabolism and Cycling The Edaphic Factor Assimilation of N Sources of N in the soil Losses of N in the soil o Organic matter plant residues and o Denitrification bacteria reduce manures N0339 to N2 gas o Fertilization with inorganic N fertilizers NH3 ammonia VOlatilization o Nitrogen Fixation in the roots of NO339 leaChing nodulated legumes Rhizobium bacteria fix USe Of N by the crop N from atmospheric N2 gas to NH4 Concentrations gt The Edaphic Factor Transformations of N in the soil Straw 39 39 Mlcroblal biomass Mineralization transformation of organic N to NH3 Nitri cation an oxidation process conversion of NH4 to N0239 and N0339 by bacteria in the soil Immobilization temporary immobilization of inorganic N by microbial organisms in the soil in the decomposition of straw or other organic materials Time gt The Edaphic Factor The Eda39phic Factor NUE of control Nitrogen use efficiency in soft white winter wheat is influenced by water availability llO O Moro 100 v Pendleton 90 80 V 70 60 50 0 20 40 60 80 Applied N kg ha39l lOO Nitrogen use ef ciency NUE is dependent on factors that often interact with one another NUE can be attributed to management N rate timing form soil factors volatilization denitrification immobilization leaching plant factors disease lodging and environment precipitation temperature At Pendleton a high rainfall site Wheat plants are more efficient in taking up applied N than at low rainfall Moro Yield NUE N Supply Water use efficiency in soft white winter wheat is influenced by nitrogen availability WUE kg ha391 mm39l 8 Ch 4 J H 0 More v Pendleton 0 20 40 60 80 Applied N kg ha39l 100 Water use ef ciency WUE is a measure of a crop s yield production in relation to the amount of water available Nitrogen nutrition is a major factor affecting WUE in Winter Wheat More nitrogen in required in higher rainfall areas Pendleton than in low rainfall areas Moro to achieve optimum WUE WUE Yield Precipitation Irrigation 1 V i a V 39 f39 I Spring Barley Typical WheatFallow Sequence 1Crop Year Drill wheat SeptOct Harvest wheat JulyAug 2Fallow Year Chisel Sept Stubble field SeptApril Sweep till April Rodweeding Summer Fallow is the practice of no crop being grown for one or more growing seasons in low precipitation areas The objectives of fallow are to conserve water and control weeds for production of a subsequent crop but soil erosion can limit the effectiveness of this practice Fallow Storage Ef ciency ranges from 10 to 40 and depends on how the soil surface is managed Fallow Storage Water Stored Efficiency X 100 Precipitation Wheat yield and water use efficiency of continuous wheat and fallow at various locations WheatWheat WheatFallow Rainfall Yield Yield Location mm kgha WUE kgha WUE Akron CO 419 498 12 1426 17 Colby KS 470 626 13 1318 14 North Platte NB 495 834 17 2146 22 Pendleton OR 404 1259 31 3590 44 Moro OR 290 781 27 2006 35 Lind WA 241 875 36 1760 37 Effect of previous crop and tillage on soil erosion losses The Factor Previous Tillage Residue Water Runoff Soil Erosion o Erosion is the major Crop Cover inches tonsacre drawback Oft lagebased Fallow Plow 10 29 85 fallow Systems Wheat Chisel 35 09 04 M m Wheat Notill 96 08 Surface residue effects on a infiltration of rainfall and b water storage in fallow fields i V CSS 200 Crop Ecology and Morphology 4 Oregon State n Respiration and Carbon Partitioning Aerobic respiration is the controlled oxidation of reduced carbon substrates such as a carbohydrate to CO2 and H20 0 This oxidation not only provides energy for plant metabolic processes but also provides the essential building blocks for crop growth and development In the plant respiration provides energy for crop growth and development Growing a crop is building a biological solar energy saf ower collector OZ CHZO coz HZOATP Reduced Oxidized Chemical Carbon Carbon energy Outer membrane Matrix Cytosol Z 5 er membrane Cristae Mitochondrial structure Respiration takes place in the mitochondria and glyoxysomes specialized organelles and in the cellular cytoplasm Membranes in the mitochondria divide the organelle into four compartments Oxidative phosphorylation electron transfer takes place along the inner membrane The matrix contains the citric acid cycle enzymes Soil Depth cm 50 Soil 02 concentration l l 103 02 01 Soil CO2 concentration Aerobic respiration is an oxygen requiring process and for the aerial portions of the plant oxygen is not limited except in times of ooding The soil atmosphere on the other hand is limits the aerobic respiration that can take place in the plant s root system 02 concentration decreases with increasing depth in the soil pro le whereas CO2 increases with depth l Pentose Sucrose Glucose gt Phosphate l Pathway quot39 Cellulose l Glycolysls DNA RNA NADPH ATP 1 Pyruvate l FattyAcid Amino Acids Proteins Biosynthesis AcetleOA Citric Acid Cycle Porphyrlns gt Chlorophyll 39 02 gt Oxidative Phosphorylation gt Membranes Electron Transfer Chain H20 Xylr39m Phloem Partitioning is the preferential distribution of photosynthetic products known as photoassimilates to various parts of the plant including the components of crop yield Photoassirnilates carbon serve as substrates for growth and development processes and respiration Source is the site of carbon production or storage Mature leaves and some stems are sources Sink is the site of utilization of carbon Carbon in the form of photoassimilates moves from sources to sinks Young leaves fruits and seeds buds and roots are sinks they import carbon to support growth and metabolic activity 1 5m Translocation is the process of moving carbon s 39 x to storage organs other sinks and to provide I these for the nonphotosynthetic parts of the plant Xylem movement is acropetal and unidirectional from the roots in the transpiration stream Phloem movement is bi directional basipetal or acropetal Transport form Sucrose is the most 333 important transport form for the translocation of carbon Others include raf nose and stachyose important in many dicots mannitol and sorbitol VI V v H o nocu20 H S I M UCrOSe C s x w 5 no 0quot H OWHZOH 7 4 V I Sou rccs g1 E A Growth 3 8 8 m g gt a 39z 6 E E on T E 4 5 E 4 5 2 0 I 0 20 45 7O 95 120 145 Position along stem mm B Sucrose unloading 23 E E E a 1 Pea leaf and stem 0 20 45 70 95 120 145 Position along stem mm Plemule Stem 40 g 35 T10 Carbon Partitioning 30 Age of tiller affects carbon export g 25 from the mainstem to tillers in 3 perenn1a1 ryegrass g 20 T9 Older tillers TlT6 are i 15 T8 independent of the seedling E 10 mainstem While younger tillers T7 E 5 T7 T6T2 T10 are not independent and I I require carbon from the mainstem 0 39 for then development 0 20 40 60 80 7 Tiller Dry Weight mg Relationship of tiller dry weight to radiolabeled I 39 w y m aquot r carbon from the mainstem in perennial ryegrass 4 a i 5 Connection of tillers in grass plant crown Potato tuber Carbon is stored in some organs and is used for crop growth and development grain lling etc Organs involved in storage of carbon include seeds stem bases roots rhizomes tuber etc Leaves are a site of temporary storage Starch storage takes place in the chloroplast for later mobilization Starch is usually broken down and moved out of the chloroplast at night Sucrose can also be stored in leaves Storage is used to supply photoassimilate for the regrowth of forage crops after defoliation If plants are defoliated too often Without replenishment of stored carbon then plants may die or suffer from reduced productivity Tuber dry WI 9 per piano Tuber no per piant e 2U 4U 6U EU Days after emergence mu 12D 2U El Days after emergence 12 Carbon P2 1g Assimilated carbon is delivered to the tuber Via the phloem as sucrose and is carbon substrate for starch synthesis and storage in e tuber Maximum tuber number is reached prior to maximum tuber weight Tubers are first formed and then filled primarily with starch 7 amylose or amylopectin 0120quot 0120quot n 0n 0 own 0 n on Amylopectin o n it own 0 n on c o Photosynthesis in leaf canopy Source Translocation of sucrose through stem Sinks atquot it A at Starch synthesis and storage in tubers Starch g per plant 70 60 50 4o 30 20 20 40 60 80 100 Days after emergence 120 Carbon Partitioning i V CSS 200 Crop Ecology and Morphology 4 Oregon State n Communities and Cropping Systems i J A crop community is a population stand or assemblage or populations of crop plants in a given place such as a field Characteristics of communities include Species diversity number of species that live in the community Growth form and structure morphology of the community Dominance relative importance of species in the community Relative abundance the proportion of the different species that reside in the community Establishment of and change in plant communities through succession after glaciers receded Natural plant communities change over time through a process known as succession Beginning with an initial disturbance in a community the composition and the relative abundance of plant species change over time in a natural community Eventually the plant community reaches a stable state known as the climax in which the abundance and composition of plant species is best adapted to the local environment The first species to appear in the community are pioneer species Community cover 100 75 Crabgrass Horseweed 50 Broomsedge Shortleaf Pine Oak 2 5 O O 20 4O 6O 80 100 Years after last cultivation 120 Succession in abandoned farmland in North Carolina Adapted from Billings 1938 In crop communities succession is not generally an issue when annual species are grown as the field is disturbed each year Perennial crop communities such as pastures can and do change over time through succession If we abandon a farm field and no longer cultivate it the field will revert to the climax vegetation state after a long time through a sequence of plant succession In the shortterm weeds can dominate in both annual and perennial cropping systems as well as in abandoned fields H 4 Communities Distribution of light in a crop Penetrating Light passes through canopy Without coming in contact with foliage Re ected Green wavelengths are re ected from foliage T ransmttted Light passes through canopy at a given level above soil surface including all of the above types Absorbed Light utilized in plant processes Crop communities may consist of a population of a single species monoculture or populations of two or more species multiple cropping also known as polycultures or mixed cropping quot Annual ryegrass seed field monoculture top wheat and soybean multiple cropping bottom USDAARS photo soybeans in wheat stubble above Cropping systems are managed by humans so as to satisfy the human need for plant or animal products 0 A successful cropping system should make maximum efficient use of natural and applied resources when grown in the environment that the crop or crops are best adapted The manager of a cropping system must understand that crop yield and quality and profit are dependent on the interrelationships of climate soil pests cultural and economic factors White clover seed field top cotton harvest bottom Harvesting club wheat crop near Dufur Oregon Monoculture is a type of cropping system Where a single crop species is produced in a farm eld year after year over an entire region Monoculture has evolved recently in human history offering the choice of growing only the highest yielding crop each year Monoculture is practiced through annual cropping fallow crop and in a rotation with other crops Multiple cropping systems involve the growing of two or more crops in one of several ways 1 Double or sequential cropping The production of two or more successive crops in the same field in one year with a short break between crops Crop 1 is planted and harvested then Crop 2 is planted and harvested Only successful in regions with long growing seasons 2 Relay cropping The production of two crops so that Crop 2 is planted prior to the harvest of Crop 1 Can be done in regions with moderate length growing seasons Doublecropping corn sown in herbicidetreated hay field top NRCS photo Relaycropped wheat and soybeans bottom USDAARS photo 3 Intercropping or mixed cropping systems The production of 2 or more crops so that most if not all of their growth overlaps in time and space Mixed planting involves the random planting arrangement of crops in a field Interplanting refers to the confinement of each crop to distinct rows planting patterns or strips Companion cropping of creeping 4 Companion cropping or undersowing red fescue seed crop with wheat The planting Of an annual crop With a perennial crop so that their growth overlaps only for the time that the annual crop is present This method is used when the perennial does not produce a crop in the first year after establishment or when the perennial grows so slowly that the soil is subject to erosion losses or is susceptible to weed infestations Multiple cropping systems may better utilize resources than monoculture Increased diversity may improve the management of pest populations in the cropping system However competition for light water and nutrients will take place among the crops and in turn this may lead to reductions in crop yield quality and profit These systems are Widely practiced world Wide Where hand labor is common but requires much greater management skill if mechanized farming practices are used Cassava intercropped with banana top shaded Kentucky bluegrass under wheat companion crop canopy bottom Plots at Rothamsted England the Morrow Plots bottom top and Crop rotation is a cropping system where different crops are grown in succession over time on the same land Modern crop rotation began in England in 1730 The Norfolk rotation consisted of a fouryear sequence of turnips barley clover and wheat Year 1 turnips Year 2 barley Year 3 clover Year 4 wheat Early research on crop rotation was conducted at Rothamsted England and in the Morrow Plots at the University of Illinois a Corn and alfalfa strip cropping in Iowa 5 top and soybean corn and alfalfa fields in Pennsylvania bottom N Reasons for Crop Rotation Yield may be greater when crops are grown in rotation Reduction in the incidence and severity of some pests Some diseases insects weeds and other pest problems can be minimized or eliminated through rotation Legumes may improve the N status of the soil Growing legumes in the rotation may provide N for subsequent crops through N fixation Soil may be protected from erosion when crops are rotated Risk may be lessened when crops are rotated Crop rotation in the dryland cereal crop production regions of the inland Pacific Northwest Mid rainfall 1218 inches Low rainfall Year lt 12 inches High rainfall gt 18 inches 1 Fallow Fallow Winter wheat 2 Winter wheat Winter wheat Spring barley 3 Fallow Spring barley Peas or lentils 4 Winter wheat Fallow Winter wheat Crop rotation effects on wheat yield in the mid rainfall area of Oregon Wheat yield Rotation bushels acre Continuous winter wheat W 69 WWpea 9O WWfallow 124 WWspring barleyfallow 92 Crop sequence is important as the preceding crops have effects on subsequent crops in the rotation If the preceding crop harbors pests that affect a subsequent crop or if the preceding crop uses soil water or nitrogen to the detriment of the subsequent crop then crop yields may be reduced The type of rotation that is employed in an farming system is dependant on climate soils and other factors Effect of crop rotation on yield of winter wheat at two locations in northeastern oregon Including peas in the rotation increases the yield of Wheat in both 50 locations but the Wheat yield was I Pendleton greatest at Weston a higher rainfall A 40 I Weston location than Pendleton Peas are better adapted to the higher 3 3o rainfall found at Weston than at 5 Pendleton Peas are more competitive E 20 with weeds and fix rnore nitrogen at 3 Weston than at Pendleton 1o 0 WheatWheat WheatPeas Crop Rotation Pests With grass family crops as the major economic crop in a region rotating to crops unrelated to grasses can disrupt pest life cycles that reduce production when these crops are grown without rotation Some wheat diseases are less severe when peas are grown in the rotation but rusts are not affected by rotation Grass family weeds are difficult to control in grass family crops By rotating to nongrass family crops selective herbicides can be used to control grass family weeds Lack of nongrass rotation crops in Willamette Valley grass seed fields has lead to increased weed populations and herbicideresistant weeds Soil Productivity and Rotation Longterm traf c in grass seed elds produces high bulk density soil layers pans that restrict the rooting of grasses By rotating to crops With taproot systems Which can penetrate the pans the development of roots in subsequent brous rooted crops such as grasses is less restricted V CSS 200 Crop Ecology and Morphology Oregon State n The Temperature Factor Photosynthetic Rate g CO2 m392 h391 I I l O 20 30 Leaf temperature C e Temperature Factor The Temperature Factor Cellular events during freezing Extracellular Freezing 7 super cooling of the cell and extra cellular solution precedes freezing As the amount of extracellular ice increases the solute concentration of the extracellular solution is increased causing freezing point depression Dehydration eventually causes collapse of the protoplast Intracellular Freezing Ice formation can sometimes be limited to vacuoles but most plants tolerate little ice formation in the cell Death results from protoplast destruction The Temperature Factor Freezin sensitive Fre zin toleranf The Temperature Factor Osmotic loss occurs during freezing and cell surface area decreases m Glucose FrLictose umol 9391 HA L O O I 00 D I 60 4o 20 50C 50C 25 C Shoots 25 C v Shoots 5 c 50C Roots 25 C ltgt Roots 5 c A 39 v v o C ltgt quotquot l l I Spring Spring x Winter Winter Cultivar The Temperature Factor Acclimation or cold hardening tolerance to low temperatures can be achieved if plants are hardened at low temperature prior to exposure Solutes including sugars certain proteins and amino acids accumulate at temperatures just above freezing Sugars that accumulate in the vacuole decrease the amount of ice formed Sugars may also protect the cell against freezeinduced dehydration Water soluble carbohydrate accumulation in roots and shoots of spring wheat winter wheat and spring x winter crosses Equiza et al 1997 The Temperature Factor High temperatureinduced color banding in seedling wheat leaves 60 nthesis 5391 J O 5 Net Photos umol m n o 45 30 35 40 Leaf Temperature C a Gradual exposure to heat n Rapid exposure to heat Cra sBrandner and Salvucci 2002 e Tem erat re Fact The Temperature Factor kghaC Yield Reduction 00 O 70 G G I 50 40 30 20 10 0 l l 20 25 30 35 40 Maximum Temperature C High temperature effects during flowering and pod development on yield of green peas Pumphrey and Ramig 1990 The Temperature Factor Grain Yield quotn or 20 c yield 3 c 00 The Temperature Factor 0 K Timing of heat impacts wheat grain yield adapted from 80 40 10 a War 15 d am 20 d am Gibson and Paulsen 1999 20 anthesis 39 0 r l l v I 20 225 25 275 20 225 25 275 275 Temperature C Temperature C Temperamre C Wheat seed Seed Yield of Control ontrol 3 Days 5 Days 7 Days Exposure to 40 C at flowering Seed yield response in flax to hi h temperature stress during flowering Values are means of 7 cultivars Gusta et al 1997 Flax seed V CSS 200 Crop Ecology and Morphology I Oregon State n Plant and Seed Identi cation H elianthus animus Asteraceae Annual plant simple leaves In orescence is a head consisting of ray and disk owers Fruit an achene Uses seed is grown for human or animal consumption oil from seed is used for vegetable oil or biofuel T riticum aestz39vum Poaceae Annual plant ligule is short and auricles are long and clasping In orescence is a spike may be with awns or awnless 0 Fruit a caryopsis cheeks on opposite side of embryo 0 Uses grain is grown for human or animal consumption vegetation is also used for forage 4 age Poa pratensz39s Poaceae Perennial plant ligule very short and auricles are absent Vshaped leaf blades with boatshaped leaf tip rhizomes In orescence is a panicle Fruit a caryopsis Uses turf or forage grass important seed crop in the northwest Brassica napus var napus Brassicaceae Annual plant In orescence is a raceme Fruit a silique Uses oil in seed is used for vegetable oil biolubricants and biodiesel While seed meal is used or livestock feed y T rifolz um repens Fabaceae Perennial plant compound leaves In orescence is a head Fruit a legume Uses important forage crop grown for seed in Oregon T rifolz um pratense Fabaceae Biennial plant compound leaves In orescence is a head Fruit a legume Uses important forage crop grown for seed in Oregon Lolium perenne Poaceae Perennial plant ligule 05 to 2 mm long leaf vernation is folded auricles short In orescence is a spike Fruit a caryopsis attened rachilla Uses important turf and forage crop grown for seed in Oregon Hordeum vulgare Poaceae Annual plant ligule long leaf vernation is rolled auricles long and clasping In orescence is a spike Fruit a caryopsis Uses important crop for animal feed and forage some human food uses malting types are used in beer production Medicago sativa ssp sativa Fabaceae Perennial plant In orescence is a head Fruit a legume Uses important forage crop grown for seed in Oregon Zea mays Poaceae Annual plant Monoecious plant with male orets in staminate spikelets tassel and female orets in pistillate spikelets ear Fruit a caryopsis Uses important food feed and forage crop also used for bioethanol and beverages F estuca arundmacea Poaceae Perennial plant vernation of leaf is rolled ligule is very short auricles are short In orescence is a panicle Fruit a caryopsis rachilla not attened Uses important forage and turf crop grown for seed in Oregon 31 i l Lolium multi orum Poaceae Annual plant vernation of leaf is rolled ligule 05 to 2 mm auricles are long and clawlike In orescence is a spike Fruit a caryopsis rachilla is attened Uses important forage and turf crop grown for seed in Oregon Dactylz39s glomerata Poaceae Perennial plant vernation of leaf is folded ligule long auricles are absent In orescence is a panicle Fruit a caryopsis Uses important forage crop grown for seed in Oregon F estuca rubm var commutata Poaceae Perennial plant very narrow leaf vernation of leaf is folded ligule 05 mm long auricles are absent In orescence is a panicle Fruit a caryopsis Uses important turf crop grown for seed in Oregon Pisum sativum Fabaceae Annual plant compound leaves Flowers are not arranged in an in orescence Fruit a legume Uses important food crop Solanum luberosum Solanaceae Annual plant compound leaves Flowers are not arranged in an in orescence Fruit a berry Uses harvested for tubers an important food crop Daucus carota ssp sativus Apiaceae Biennial plant compound leaves In orescence is an umbel Fruit a schizocarp Uses harvested for roots an important food crop and a seed crop in the Pacific Northwest
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