Effect of Temperatures on Plant Growth

exit of Temperatures on Plant GrowthChapter 5IMPLEMENTATIONThe arrange festering module computes the crop product and cultivation establish on day by day fosters of supreme and minimum temperatures, radiation and routine value of soil stress factors. The values atomic telephone number 18 added together to give an estimate of the amount of eraal ingathering your defines lose achieved. Plant growth prediction model depends on the plant para quantifys like,TemperatureRelative humidness rainfallSolar radiation.5.1 Effect of TemperatureTemperature factors that figure into plant growth potential differences include the following level best daily temperature stripped daily temperatureDifference between day and night temperatureAverage daylight temperatureAverage nighttime temperaturea longsighted with these there are sepa compute considerations such as5.1.1 MicroclimatesThe microclimate of a garden plays a primary business office in actual garden temperature. In great deal communities, changes in elevation, air drainage, exposure and thermal shake up mass (surrounding rocks) will make gardens importantly warmer or modifyer than the temperatures recorded for the are.In mountain communities, it is important to know where the topical anesthetic weather station is located so gardeners can factor in the difference in their specific locations to forecast temperatures more accu enjoinly.5.1.2 Thermal heat mass (surrounding rocks)In many a nonher(prenominal) Colorado communities, the surrounding rock formations can form heat sinks creating wonderful gardening spots for local gardeners. Nestled in among the mountains some gardeners have growing seasons several weeks longer than neighbors lonesome(prenominal) a half(a) a mile away. In cooler locations, rock mulch may give some rhyme protection and increment temperatures for enhanced crop growth. In warmer locations rock mulch can significantly increase summer temperatures and water requirements of landscape plants.5.1.3 Influence of heat on Crop GrowthTemperature affects the growth and productivity of plants, depending on whether the plant is a warm season or cool season crop.Photosynthesis inwardly limits, rates of photosynthesis and respiration both set up with increasing temperatures. As temperatures reach the upper growing limits for the crop, the rate of food utilize by respiration may exceed the rate at which food is fabricate by photosynthesis. For tomatoes, growth peaks at 96F.Temperature influence on growth sources of cool season crops germinate at 40 to 80.Warm season crop seeds germinate at 50F to 90F.In the spring, cool soil temperatures may prohibit seed germination.Examples of temperature influence on floweringTomatoesPollen does not develop if night temperatures are below 55FBlossoms drop if daytime temperatures rise above 95F before 10 amTomatoes grown in cool climates will have softer fruit with bland flavors.Spinach (a cool season, short day crop) flower s in warm weather with long days.Christmas cacti and poinsettias flower in response to cool temperatures and short days.Examples of temperature influence on crop quality elevated temperatures increase respiration rates, reducing sugar content of produce. Fruits and vegetables grown in heat will be less sweet.In heat, crop yields reduce while water demand goes up.In hot weather, flowers color in fade and flowers have a shorter life.The disconcert 5.1 llustrates temperature differences in warm season and cool season CropsTable 6.1 Temperature comparison of cool season and warm season cropsTemperature forCool seasonBroccoli, cabbageWarm seasonTomatoes, peppersGermination40f to 90f,80f optimal50f to 100f,80f optimumGrowthDaytime65F to 80F preferred40F minimumNighttime32F,tender transplantsmid-20F,established plantsDaytime86F optimum60F minimumA week below 55F will stunt plant, reducing yieldsNighttime32FFloweringTemperature extremes cartroad to boiling and buttoning.Nighttime95F by 10 am, blossoms abortSoilCool wasting disease organic mulch to cool soilSince seeds germinate best in warm soils, use transplants for spring planting, and direct seeding for mid-summer planting(fall harvest)WarmUse black plastic mulch to warm soil, increasing yields and earliness of crop.5.1.4 Influence of cold temperaturesThe temperature variation over karnataka for the geezerhood 2008,2009,2010.2011 is shown in the figure 6.2. this in any case shows a clear annual cycle in the temp rise in feb-may and then falls during monsoon and winter.fig 6.2 TEMPERATURE VARIATION OVER KARNATAKA FROM YEAR 2008-20115.2 Effect of Relative humidityRelative humidityis the ratio of the partial pressure of water evaporation in an air-water concoction to the saturated vapor pressure of water at a prescribed temperature. The relative humidity of air depends not only on temperature but also on the pressure of the system of interest.5.2.1 MeasurementThe humidity of an air-water vapour mixture is dete rmined done the use of psychometric charts if both the change bulb temperature(T) and thewet bulb temperature(Tw) of the mixture are known. These quantities are readily estimated by using a slingpsychometer.There are several empirical correlations that can be used to estimate the saturated vapour pressure of water vapour as a service of temperature. TheAntoine equationis among the least complex of these formulas, having only three parameters (A, B, and C). Other correlations, such as those presented byGoff-GratchandMagnus Tetens approximation, are more alter but yield better accuracy. The correlation presented byBuckis commonly encountered in the literature and provides a reasonable labyrinthine sense between complexity and accuracy.whereis the dry bulb temperature expressed in degrees Celsius (C),is the absolute pressure expressed in hectopascals (hPa), andis the saturated vapour pressure expressed in hectopascals (hPa).Buck has reported that the upper limit relative fallacy i s less than 0.20% between -20C and +50C when this particular form of the generalized formula is used to estimate the saturated vapour pressure of water.5.2.2 Pressure DependenceThe relative humidity of an air-water system is parasitical not only on the temperature but also on the absolute pressure of the system of interest. This dependence is demonstrated by considering the air-water system shown below. The system is closed (i.e., no count enters or chokes the system). The relative humidity over Karnatakafor the years 2008,2009,2010.2011 is shown in the figure 6.4 figure 6.4 RELATIVE HU MIDITY OVER KARNATAKA 2008-20115.3 Effect of RainfallFig 6.5 RAIN ANOMALY (top panel) Vs COFFEE AND Rice production over Karnataka5.4 Effect of Solar Radiation cheerfulness is a portionof the electromagnetic radiation habituated off by the Sun, particularly infrared, visible, and ultraviolet light. On Earth, cheerfulness is filtered through the Earths atmosphere, and is obvious as daylight when the Sun is above the horizon. When the direct solar radiation is not obstruct by clouds, it is experienced as sunniness, a combination of bright light and radiant heat. When it is blocked by the clouds or reflects off other objects, it is experienced as diffused light. The World Meteorological system of rules uses the term sunshine duration to mean the cumulative time during which an area receives direct irradiance from the Sun of at least 120 watts per square meter.Sunlight may be recorded using a sunshine recorder, pyranometer or pyrheliometer. Sunlight takes about 8.3 minutes to reach the Earth. On average, it takes energy between 10,000 and 170,000 years to leave the suns interior and then be emitted from the surface as light.Direct sunlight has a luminous competency of about 93 lumens per watt of radiant flux. Bright sunlight provides illuminance of approximately 100,000 luxors lumens per square meter at the Earths surface. The entireness amount of energy received at grou nd level from the sun at the zenith is 1004 watts per square meter, which is composed of 527 watts of infrared radiation, 445 watts of visible light, and 32 watts of ultraviolet radiation. At the top of the atmosphere sunlight is about 30% more intense, with more than three times the fraction of ultraviolet (UV), with most of the surplus UV consisting of biologically-damaging shortwave ultraviolet.Sunlight is a key factor in photosynthesis, the process used by plants and other autotrophic organisms to convert light energy, normally from the sun, into chemical energy that can be used to give the axe the organisms actThe solar radiation over karnataka for the years 2008,2009,2010.2011 is shown in the figure 6.7, which shows maximum radiation in summer and it decreases in winter.2008 2009 2010 2011Fig 6.6 SOLAR RADIATION OVER KODAGU FROM 2008-2011MODULES OF THE PLANT GROWTH MODELThe plant growth module computes crop growth and development based on daily values of maximum and minimum temperatures radiation and the daily value of two soil water stress factors, SWFAC1 and SWFAC2. This module also simulates jerk area index (LAI), which is used in the soil water module to compute evapotranspiration.7.1 low-level formatting infix variables, as listed in table 1, are read from file PLANT.INP. File PLANT.OUT is opened and a header is written to this output file.Table 7.1 input data read for plant moduleInput data read for plant moduleVariable namedefinitionUnitsEMP1Empirical coefficient for LAI computation ,maximum leaf area expansion per leafm 2/leafEMP2Empirical coefficient for LAI computationFcFraction of total crop growth portioned to canopyIntotDuration of reproductive stageDegree-daysLaiLeaf area indexM2/m2LfmaxMaximum number of leavesNLeaf numberNbEmpirical coefficient for LAI computationP1Dry matter of leaves removed per plant per unit development after maximum number of leaves is reachedGPDPlant tightnessPlants/m2RmMaximum rate of leaf appearanceLeaf/daySla Specific leaf areaM2/gTbBase temperature above which reproductive growth occursCWTotal plant dry matterg/m2WcCanopy dry matter weightg/m2WrRoot dry matter weightg/m27.2 Rate calculationsThe plant module calls three subroutines PTS to calculate the effect of temperature on daily plant growth rate and rate of leaf number increase PGS to calculate daily plant weight increase (g/plant) and LAIS to calculate in leaf area index.In subroutine PTS the growth rate reduction factor (PT) is calculated every day using the following equationPT=1-0.0025((0.25TMIN + 0.75 TMAX)-26)2Where TMIN and TMAX are the minimum and maximum daily temperatures.Subroutines PGS calculate PG, the potential daily total dry matter increase (g/plant) where SRAD is the daily solar radiation and PD is the plant density.SRADY1 is obtained byY1 =1.5 -0.768. ((ROWASPC .0.01)2 .PD)0.1Where ROWSPC is the row spacing in cm. The potential plant growth rate is limited by soil water stress through SWFAC and temperature through PT.The plant cycle is divided in vegetational and reproductive phrases. The vegetative phase continues until the plant reaches a genetically determined maximum leaf number. During the vegetative phase, leaf number increase is calculated based on maximum rate and a temperature based limiting factor.During reproductive phase, the difference between daily mean temperature and a base temperature is used to calculate the rate of plant development. Total rate of development towards maturity is accumulated as int.Subroutine LAIS is called for phases to compute the change in leaf area index. During vegetative period, LAI increases as a function of the rate of leaf number increase. The potential rate is limited by soil water stress, through SWFAC and temperature through PT. Its value is given bydLAI=SWFAC. PT.PD.EMP1. Dn.a/1+awhere PD is the plant density , EMP1 is the maximum leaf area expansion per leaf, and a is given by a= eEMP2.(N-nb)Where EMP2 and nb are coefficients in the expolinear equation and N is the development age of the plant.After plant has reached the maximum number of leaves, LAI starts to decrease as a function of the daily thermal integral, di. The rate of decrease is given by dLAI= -PD.di.p1.SLAWhere P1 is the dry matter of leaves removed per plant per unit development after maximum number of leaves is reached and SLA is the specific leaf area.7.3 IntegrationChanges to leaf area index, plant weights and leaf number are co-ordinated into the appropriate state variables at the beginning of the integration section.7.4 OutputDaily output is written in PLANT.OUT file.7.5 CloseThe PLANT.OUT output file is closed.Fig 7.1 Planning the Concept Of Dynamical Agriculture Model