Akinyoola Journal

IOSR Journal of Agriculture and Veterinary Science (IOSR-JAVS)e-ISSN: 2319-2380, p-ISSN: 2319-2372. Volume X, Issue X (Jan. - Feb. 2013), PP 00-00www.iosrjournals.org

Microclimate Factors for Sustenance and OptimumCrop Production in Greenhouse System

Akinyoola, J.A1, Ologunagba F.O1, Omonijo G.2

1(Agricultural Engineering Technology Department, Rufus Giwa Polytechnic, P.M.B 1019, Owo,Nigeria)

2(Agricultural Technology Department, Rufus Giwa Polytechnic, P.M.B 1019, Owo, Nigeria)

Abstract: Greenhouse system is an alternative to economic problems faced as a result of climatevariability which has so far hindered agricultural practices, hydropower, hydrological cycle anddrought relieve. The survey covers green house system and management within humid tropical areaof Nigeria. The study includes crops of different types such as Cucumber and Sweet Melon. It coverwithin the period of sowing (nursery), transplanting and harvesting. The result revealed that thenecessary microclimate factors such as Temperature of 280C and Relative Humidity of 85% arenecessary for the maximum growth, development and productivity of these crops. Highertemperature aids flowering and support photoperiodism. Crops suffer low quality output andinvasion of pests and diseases when humidity threshold is at minima.Keywords: Green house, nursery, transplanting, harvesting and photoperiodic

I. IntroductionClimate is referred to as a statistical weather condition over a place say30-50 years Hermann 1969.But in reality, climate can be regarded as the characteristics condition ofthe atmosphere near the earth surface at a given place or over a givenregion since it is always changing in time and space. On the other hand,weather is a state or condition of atmosphere at a given place and at agiven time.

It is a variations or conditions of lower layer of the atmosphere.Weather pertains of smaller areas like villages and districts are expressedby numerical values of meteorological parameters such as solar radiation,air temperature, atmospheric pressure, wind speed, relative humidity,precipitation and clouds.Solar energy is the main factors influencing temperature and thus variesfrom one place to another. The principal heating of air during the day isproduced by its contact with a land surface that has been heated by theSun's radiation. Heat from the ground is communicated to the air byconduction and convection.

Greenhouse System is primarily built for temperature controlpurposes, which also influence other meteorological elements. Ordinaryglass transmits short wave radiation, but absorbs the long wave "heat"radiation from terrestrial sources (green house effect). However, heat isconducted through the glass and is dissipated from the outer surface partlyby radiation and partly by convection. Compare with metals, glass is a poorconductor, but it conduct well than many insulating and building materials.

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ebcid:com.britannica.oec2.identifier.ArticleIdentifier?articleId=26084&library=EB&query=null&title=convection#9026084.toc

ebcid:com.britannica.oec2.identifier.ArticleIdentifier?articleId=72067&library=EB&query=null&title=conduction#9072067.toc

Microclimate Factors for Sustenance and Optimum Crop Production in Greenhouse System

The surface layers absorb solar energy, 'which reaches the ground, bythe structure and its contents. In the absence of convective exchange, heatis retained and the amount stored increases above that which occurs in theopen. The excess of inside temperature over which occur in the day would beexpected to be greater on sunny days than overcast days (seaman, 1957).

If these results are interpreted in terms of their effect on thetiming of commencement of the growing season, a gain of three to four weeksis indicated. Such gain in temperature may be advised in early season,during germination and emergence of crop when the soil is effectively bare.It must be emphasized that the presence of a vegetable lower like cucumberand sweet Mellon will reduce the temperature difference, due partly to theshading of the ground and partly to the heat required for transpiration.A general consideration of soil temperature variations reveals that theheat transport in the soil in the green house and that in the open aresimilar. However, for all depths, the green house soil is significantlywarmer than that in the open.

More importantly, low relative humidity can be obtained in the greenhouse in practice either by increasing the air temperature or byventilation. High relative humidity can also be obtained by increasingevaporation from the soil into the green house with relatively low airtemperature.

Solar energy provides light required for seed germination, leafexpansion, growth of stem and shoot, flowering, Fruiting and thermalconditions necessary for the physiological functions of the plant.

More than 70 percent of the solar radiation absorbed by plant is convertedinto heat. This heat energy is utilized for transpiration and convectiveheat exchange with the surrounding. This exchange determined thetemperature of leaves and other plants parts.

1.1 Effect of Temperature and PhotoperiodismThe photoperiodic effect is realized only when optimum temperature

prevails. Even in photosensitive variety. Flowering is not induced when thetemperature is extremely low. However, within the normal range, temperatureadvances or hastens flowering.

However, Relative lengths of day and night not only influenceflowering but also affect other processes like initiation of leaves,tillers etc. Number of leaves produced is less with decrease and increasein photoperiod with short and long day plants respectively. Leaf numberincreases with increase in temperature. Similarly, increase in duration oflight for long plant and temperature decreases.

However, Relative humidity (RH) directly influences the waterrelations of plant and indirectly affects leaves growth, photosynthesispollination, occurrence of diseases and pest and final economic yield. Thedryness of atmosphere as represented by saturation deficit (100-RH) reducesdry matter production through stomata control and leaf water potential.

Relative humidity have a considerable influence on evapotranspirationand water requirement for crops. At constant temperature, changes inatmospheric humidity affect transpiration by modifying the vapor pressure



gradient from leaf to air different stages of crop, especially duringvegetative phase.

1.2 Objective of the Study (a) It aim at creating higher ambient and soil temperature, reducing the

risk of low temperature which provide facilities for the control ofsoil moisture and humidity.

(b). to determine the extent to which micro-climatic elements influencegreen house system in South-western area of Nigeria.

(c) Identify the major constraint affecting green house system.

II. MethodologyAbout 400 to 500 litter of water is necessary for the production of a

kilo of plant dry matter. Water is also required for translocation ofnutrients and dissipation of heat, Irrigation however, is the artificialapplication of water to soil supplement rainfall for crop production.Irrigation provides favourable environment for higher crop growth andyield.

There are various types of irrigation systems which includes:sprinkler and drip irrigation etc. In this study more emphasis is laid ondrip irrigation system being the best method adopted in this research.Drip irrigation is the precise slow application of water in the form ofdiscrete or continuous or tiny streams covertures spray through mechanicaldevices called emitters or application located at selected points alongwater delivery times. The term triple or drip irrigation are used.

In 1964 the first patented drip irrigation system was developed andestablished by Richard Chapin. By the late sixties. This concept spread toAustralia and USA. And eventually to several countries in the world Dripirrigation is adopted extensively in green house system and especially forcrops such as cucumber, Sweet Mello, Tomatoes, Green pepper, Lettuce etc.Drip irrigation system consist of the following components:i. Pump to life the water from the same of supply.ii. A head unit consisting of a tank to maintain the required pressure for

circulation of water.iii. A central distribution system, connected, to mean water supply, which

regulates water pressure and quantityiv. A fertilizer tank, connected to the central distribution system to

remove materials suspended in water.v. A filter, connected to the central distribution system, to remove

materials suspended in water.vi. PVC main supply pipe o\f suitable diameter and length to deliver the

desired discharge.vii. Sub - man or laterals of suitable diameter and length connected in a

parallel way to the main andviii. Plastic dripper inserted in the lateral at the desiredix. Spacing (equal to the intra - row spacing of the plant) which control

the release of the desired quantity of water.Other types of drip irrigations includes: sub surface drip irrigationsystem where laterals are buried bellow the soil surface and pulse



irrigation system supplies water in series of pulse or discharge at aninterrals of five, ten, fifteen minutes.

2.1 Analysis of Drip Irrigation Design for Green House System Number of plants (Cucumber) =Area Spacing

=35ft =30cmX30cm

=10,50m =0.30m

=35 plantsEvaporation of crop can be estimated by pan evaporation method.

Where is the Reference evapotranspiration or potential

evapotranspiration in millimeter(mm). is the

Evapotranspirometer in millimeter (mm) and

is the Pan coefficient

This estimation is limited due to lack of instruction to plant in place. a) Drip irrigation has proved to be a success in terms of water and

increase yield in a wide range of cropsb) Increase in yield range from 20% to as high as 100%.c) The saving in water depends on crops, soil and environmental conditions.

The main reasons for saving of water are absence of conveyance and runoff losses, reduced evaporation due to Iesser-wetted area and minimum orno deep percolation. Drip irrigation provides opportunity for enhanceplant growth and yield.

Drip irrigation provides sufficient amount of water throughout thegrowing season unlike other methods where soil moisture fluctuates fromfield capacity to different degree of dryness between irrigation.Drip irrigation reduced salinity hazard to plants due to low saltconcentration owing to high availability of water continuously.Weed infestation is less with drip irrigation because only small area iswetted.

2.2 Fertigation methodFertilizers are industrially manufactured chemically containing plant

nutrients. Nutrients content is higher in fertilizers than in organicmanure and nutrients are released immediately. Straight fertilizer, arethose which supply only one primary plants nutrient, namely Nitrogen,phosphorus and potassium (NPK) which is majorly used for cucumber and sweetmelon. Mixed fertilizers are physical mixture of straight fertilizer theycontains two or three primary plant nutrients. They are made by throughmixing of the in gradients.

Physical form of fertilizers are in several forms: Powder (singlesupper phosphate crystals (ammonium Phosphat), pill ( Urea, Diammoniumphosphate, supper phosphate), Granite ( Holland Granite), Supper granite



( Urea Supper Granite and briquettes). Other fertilizers are in liquid formfor applying with irrigation water or for direct application

There are various methods of fertilizer application which includesBroad casting, broadcasting and incorporation, band placement, pointplacement, sub soil placement, fertigation, root dipping and foliar spray.Equal proportion of fertilizer and accurate amount of water and itsapplication is known as fertigation. It is generally followed with chipirrigation as used in green house system, depth with the help of hand hoesin which wed are uprooted and removed.

2.3 Phonological Observation on Developmental Phases of Cucumber and SweetMellon.

Week SweetMellon

Cucumber Observation

Week I 3leaves

2 leaves Shooting and leaveinitiation was faster insweet mellon

Week II 5leaves

4 leaves Transplanting performed.

Week III 7leaves

7 leaves First Fumigation performed

Week IV 10leaves

9 leaves Weeding performed

Week V 6FlowersObserved

Shootelongation andflowering

Flowering rate is higherin Sweet Mellon

Week VI Fruiting

Fruiting 50 % Flowering

Week VII Fruiting

Fruiting 100% flowering on SweetMellon

WeekVIII

MatureFruits

FirstHarvest

Sencond Fumigation andweeding Performed

Week IX FirstHarvesting

SecondHarvesting

Harvesting

Table 1. Phonological Observation Table

2.4 Rate of FloweringThis parameter indicate whether most of the branches lowering in

quick succession or not. In other words it indicates synchronous flowering.It is expressed as number of flowers that appears per day

Where and are the number of flowers appear per day.



Flowering rate for sweet mellon. = 3

= 1

=0900z

=1800z

FR = 3 - 1 1800-900= 2/9 = 0.2

This indicates the number of days in which 50% of the plants flowers. Forinstance 50% rate of flowering on Sweet Mellon after first week oftransplanting.It is the number of days in which plants attain maturity. Also floweringstarted after twenty days of nursery for sweet Mellon and cucumber.

When more than one crop is to be grown in a year on the same piece ofland, the time occupied by each crop has to be reduced. The seedling growthin the early stages is very slow. Seedlings need extra care forestablishing in the field because of their tenderness. Small seeded cropslike green pepper, cucumber and sweet Mellon are to be sown shallow andfrequently irrigated for proper germination and development. Taking care ofthe germinating seed or seedlings, which are spread over a large area, is aproblem with regard to application of water, weed control, pest controle.t.c.

Therefore, seeds are sown in a small area called nursery and all thecare is taken to raise the seedlings. When they grown to certain stage,they are pulled out from thee nursery and transplanted in the main field.The advantages of transplanting are good stand establishment and increaseintensity of cropping.For achieving good results from transplanting, the seedlings aretransplanted at optimum age and at proper depth. The optimum time oftransplanting cucumber and Sweet Mellon from nursery is thirteen days atinterval and the shallow depth was five centimeters (5cm) to the ground.

Emerged seedling becomes independent when the third leaf has fullyexpanded and the forth leaf just appears. However, early nursery duringcertain period increases the yield. An optimum temperature is verynecessary thereby increase yields due to suitable environment at all thegrowth stages of the crop. The figure bellow shows the nursery of cucumberand Sweet Mellon

2.5 Criteria for harvestingIn Cucumber for instance,19 days after flowering fruit increased in

size and thicken in the outer wall. While in Sweet Mellon it is 30 daysafter flowering.



Harvest maturity generally occurs several days after physiologicalmaturity. The important processes during this period is loss of moisturefrom the plants. The general symptoms of harvest maturity are:Time for harvesting can be known appropriately by the duration of Crop asmaturity on climate, Maturity symptoms are good indicator for deciding thetime for harvesting.

The data used are primary data having been collected on daily basesin side the green house from January to July which also includes theperiod of planting of cucumber and sweet Mellon from nursery to harvestingtime.

Primarily, data are very useful in this purpose as it is widely usedto find the averaged temperature per day or monthly mean temperature and tocompute monthly mean of relative humidity within the threshold which isattainable and sustainable for crop production and weather forecasting forproper farm management and pest diseases.

Jan

Feb

Mar.

April

May Jun

Jul

Mean Monthly Temp(0C)

28 29 30 29 29 25 26

Mean Monthly R.H (%) 85 84 84 83 85 88 86

Table 2. Monthly variation of Temperature and Relative Humidity

Figure 1. Monthly Variation of Temperature

Figure 2. Monthly Variation of Relative Humiditywww.iosrjournals.org

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Figure 3. Monthly Variation of Temperature with Relative Humidity

For instance, in March temperature of 30°C was recorded and this shows adrastic decrease in relative humidity of 84%. Likewise in April from figure6 the average temperature amount 29°C and this recorded the least relativehumidity of 83%. Conversely, highest average relative humidity of 88% wasrecorded in June when the temperature was amounts 270C i.e at this periodboth variables are in place. By the end of June the temperature increasesgradually while relative humidity decreases in July approaches.

Figure 7. shows variation of relative humidity with temperature. It wasclearly shown that relative humidity decreases drastically with temperatureuntil the temperature was constant at 29°C. When average temperature was30°C, the relative humidity increases of 87% at temperature of 280C.

III. Result/DiscussionComparing the phonological observation on the various phases of crop growthand development and management with graphical analysis. The followingdeductions were made:(a) In May, the average temperature was 29C with relative humidity of 84%.

It was observed that normal growth and development were recorded onboth crops and at the 13th day of Nursery transplanting was done. Thisshows the condition of temperature and relative humidity for bothcrops.

(b) In June for instance when both temperature and relativehumidity were in phase outbreak of pests and diseases were noticed.This is as a result of high amount of relative humidity (88%) recorded.Therefore, the first fumigation had to be carried out to preventdestruction or attack that might be done on the crops. The above twoimportant weather factors determining the fate of pests population. Theexact conditions experienced by a species may be modified by itsbehavior of microclimate. Host and pest multiply at rates that dependson temperature. As temperature rises, growth and reproduction of thepest increases, until the weather becomes too hot, at which time theyslow down and finally stop.



(c) Rate of flowing continues on both crops but much more significant onsweet mellon to cucumber. Up to 100% flowering was recorded by June atthe expence of high mean temperature value. The first fruit was noticedon cucumber and maturity reached on cucumber than sweet melon.

(d) As noted, temperature aids flowering'rate and this has shownclearly when 100% rate of flowing notices on both crops.

(e) Harvest of fruits was done on both crops by July. Asubsequent fruiting which has increases per area covered and thisincrease gross weight of harvestings.

(f) Optimum temperature about 280C is therefore necessary for bothsweet melon and cucumber for an efficient growth, development andfruiting. Relative humidity below or above the optimum both appropriatefor efficient growth and development on both crops. For instance highR.H. above 85% create an environment for pests and diseases.

IV. ConclusionGreen house does not prevent heat from been lost through radiation.

They do however, reduce heat lost through advection by eliminating windturbulent and effect felt particularly during daytime, and greatly reducewater loss from the crop. At night, they probably buffer the crop fromthe drastic temperature drop by the absence of heal loss due to wind flowand by creating an air layer saturated with water, thereby providing ahigher heat-capacity environment and a layer of insultation for long-waveradiation loss. Green house allow the incursion into the cold season ofvegetable crops requiring higher temperature and the supply of produce tothe market at an early date. The temperature inside the green house shouldbe approximately 2ft°C. This should be maintained to afford anyunfavourable condition that might hinder the growth and development of thecrops.However, when RH is exactly 85% funigation operation must be carried out soas to prevent damages from pests and diseases attack which might result inpoor production and low quality of fruits.

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