MAIZE

MAIZE

Botanical name: Zea mays L.

Family: Graminae

Common name: Maize, corn

Chromosome number: 2n = 20

Chemical composition

•         Composition of mature grain per 100g

-         Water 10,4 g

-         Energy 1527 kj

-         Protein 9,4g

-         Fat 4,7g

-         Carbohydrate 74,3g

-         Dietary fibre 7,3 g

-         Calcium 7mg

-         Phosphorus 210mg

-         Iron 2,7mg

-thiamin 0,39mg

-riboflavin 0,20mg

-niacin 3,6mg

-vitamin B6 0,62 mg

-folate 19μg

-ascorbic acid o mg

•         Essential amino acids composition per 100g edible portion

-tryptophan 67mg

-lysine 265 mg

-methionine

-phenylalanine 463 mg

-threonine 354 mg

-valine 477mg

-leucine 1155mg

-isoleucine 337μg

•         Principal fatty acids per 100g edible portion

-linoleic acid 2097mg

-oleic acid 1247mg

-palmitic acid 569mg

•         Endosperm (80% of weight of grain)

-poor in ph and ca

-contains most of the starch and 2/3 of proteins

-75% amylopectin

-25% amylose

USES

•         As food

-eaten fresh on the cob boiled or roasted

-seeds roasted

-grain ground or milled into mealie meal and made into porridge or papa which is eaten with vegetables or various stews

-mealie meal can be fermented into traditional beer

-baby cobs or baby corn (very young inflorescence) are vegetables especially in the western countries

-baking, snack foods

-breakfast cereals

-Ice-cream, frozen deserts

-jam, jellies

-meat products

-soups

-bread making

•         Source of starch which is made into sugars such as dextrose and fructose which are used as artificial sweeteners, laundry starch,thickeners,hardeners of paper, glue

•         Source of oil from the germ which is used for cooking, margarine,baking,soap,slads,glycerine

•         Source of ethanol which may be added to petrol to produce a blended motor fuel

•         Used to produce alcohol beverages

•         Silage to feed livestock especially in western countries where special cvs and production technologies have been developed

•         Green manure

•         Cobs used as a source of fuel

•         Stalk-fuel,fodder,thatching,compost

•         Fibre in stems and inner leaves surrounding the cob are made into paper

•         Residues from production of starch and oil are used as animal feed(corn gluten meal and corn gluten feed)

•         Tyre production

•         Compostable plastics, packaging films, fast food serving utensils manufactured with maize based polylactic acid

•         Corn based polylactic acid can be blended with cotton, wool or silk to make exercise clothing,suits,carpets

•         Pharmaceuticals

•         Cob leaves used to wrap foods, made into cloth or mats, used for mattress filling

•         Ash from burnt stem can be used as a substitute for salt

•         In southern Africa the incinerated cob is included into snuff

Medicinal uses especially in African countries

•         Urino genital problems are treated with prescriptions based on whole or parts of the maize plant especially a decoction of the styles

•         Decoction of the styles also used to treat jaundice

•         Fever is treated by drinking a leaf maceration

•         Gonorrhea is treated by charcoal made from maize stalk

•         Infusion from burnt cob is used to wash wounds

•         Water obtained during the preparation of papa is used to soak bark or roots of some plants and this is used to treat fever or malaria

•         In Nigeria whole dried maize fruit and dried yam with some charms are planted and buried together and this preparation is done to unite or bind couples together with the effect that they will never remarry

GROWTH AND DEVELOPMENT

•         Climatic requirement

 -warm season plant

•         Divisions of plant development

Vegetative

-each leaf stage is defined according to the uppermost leaf whose leaf collar is visible.

1. VE-emergence

-planted seed absorb water and begins growth radicle stars developing

2-3 days after planting followed by the coleoptile with the enclosed plumule (embryonic plant).

-Emergence is finally attained by rapid mesocotely elongation which pushes the growing coleoptile to the soil surface.

-under warm moist conditions emergence will occur within 4-5 days after planting but under cool or dry conditions it takes 2 weeks or longer.

-V3 leaf stage

-root hairs growing from the nodal roots by this time

-all leaves and ear shoots that the plant will eventually produce are being initiated at this stage.

-at about V5 leaf and ear shoot initiation will be complete and a microscopically small tassel is initiated in the stem apex.

-at this point the stem apex at tassel initiation is just under or at the soil surface although total above ground height is about 20cm.

V6 leaf stage

-the growing point and tassel are above the soil surface and the stalk begins to elongate.

-ear shoots or tillers which initially looked very similar are visible at this time.

-loss of the two lowest leaves may have already occurred by the V8 stage

V9 leaf stage

-ear shoots (potential) are visible upon dissection of a V9 plant.

-by V10, the time between the appearance of new leaf stages will shorten generally occurring every 2 to 3 days.

V12 leaf stage

-the number of ovules (potential kernels) on each ear and the size of the ear are determined at this stage

V17 leaf stage

-the tip of the tassel may also be visible at this stage

V18 leaf stage

-silks from the basal ear ovules are the first to elongate and those from the tip ovules are the last to elongate.

-brace roots (terminal aerial nodal roots) are now growing from the nodes above the soil surface.

-VT-tasselling stage

-initiated when the last branch of the tassel is completely visible and the silks have not yet emerged (are not visible)

-begins approximately 2-3 days before silk emergence during which time the corn plant will almost attain its full height and pollen shed begins

Reproductive stages

•         R1 stage-silking

-begins when any silks are visible outside husks

-pollination when fallen pollen grains are caught by the silks

-a captured pollen grain takes about 24 hrs to grow down the silk to the ovule where fertilisation occurs and the ovule becomes a kernel

-2-3 days require for all silks on a single ear to be exposed and pollinated.

•         R2-blister (10-14 days after silking)

-1st stage of grain filling

-immediately after pollination, the silk separates from the cob and the developing kernels look like a blister

-the content of the kernel is clear and jellylike

-white and yellow maize look the same at this stage

-kernels at the base of the cob develop1st and those at the tip develop last

•         R3-milk(18-22 days after silking)

-         kernel displays yellow colour on the outside, and the inner fluid is now milky white due to accumulating starch.

-         Although initially slow to develop, the embryo is growing rapidly now and is easily seen upon dissection.

-          Most of the R3 kernel has grown out from the surrounding cob materials and the silks at this time are brown and dry or becoming dry.

•         R4-dough (24-28 days after silking)

1.Soft dough stage

          -Kernel content is soft and sweet

          -kernels of yellow maize start to change colour

           -the end of this stage is ideal for picking for green maize

2.Hard dough stage

-moisture content of grain drops rapidly and kernel content changes to a paste

-formation of starch increases

-weight of the grain will be about half the actual yield

•         R5-dent (35-42 days after silking)

-correct time to cut silage

-stage is complete when all kernels have formed a dent on the crown

-moisture content of grain decreases quickly to around 50%

• Physiological maturity (55-65 days after silking)

-is reached when all kernels on the ear have attained their maximum dry weight or maximum dry weight or maximum dry matter accumulation

-black or brown abscission layer formed from the tip ear kernels to the basal kernels

-husks and many leaves may no longer be green although the stalk maybe

-colour of the husk leaves that cover the cob are 70 – 80% light brown

-MC of grain decrease from 50 to below 40%

SEED PRODUCTION

-seed grower must plant foundation seed of an approved cultivar

-the seed must be planted on clean ground free from weeds and should not have been planted to maize the previous year

-use herbicides and pesticides if necessary

-isolation of the seed producing field is required (at least 500m away)

-off-type plants should be removed

-field inspections should be made by representatives of the seed certifying agency to check the purity of the cultivar

-seed inspections necessary in harvesting, conditioning and other processing operations

-several insecticides and fungicides are used in treating seed to disinfect and disinfest them fro pathogenic organisms

-official tags supplied by seed certifying agency are sealed on the bags of seed approved for certification.

•         Seed produced by seed companies like seed-co meet the following quality standards

-germination (min)-90%

-physical purity (min)-99%

-insect damaged seeds (max)-1,5%

-diseased seed (max)-0,75%

-total defects (max)-2%

-genetic purity (min)-95%

-2 types of maize seed, open pollinated (product of natural pollination) and hybrid seed (1st generation offspring of a cross between 2 individuals differing in 1 or more genes).

-smallholder farmers generally select seed from the next crop from the last harvest.

-selected cobs are stored at home in the surrounding leaves above the fireplace to prevent insect damage

SEED STORAGE

-MC of grain should be reduced to 12-15%

-seeds are considered to be in storage from the moment they reach physiological maturity until they germinate

1. the entire storage period can be divided into the following stages

2. storage on plants (physiological harvest until harvest)

3. Harvest until processed and stored

4. In transit (railway wargons, trucks, carts, railway sheds etc)

5. On the user’s farms

-with smallholder farmers shelled grain is dried for a few days and then stored in bags, tins or baskets

-farmers in Botswana use many traditional methods of storing seeds

-woven baskets, bins made from cow dung and wood ash, earthern pots, mud granaries

on large commercial scale grain is stored in bulk in

1. Grain bin storage

-grain stored in bins of different materials (concrete, steel, wood)

-maybe airtight or ventilated

2. Grain elevators

-large silo bins are constructed together to form a grain elevator

-usually constructed at railroad siding or water fronts to facilitate grain transportation

• For commercial seed storage

1. Conditioned storage

-seeds maintained in a dry and cool environment and moisture content should be about 12-13% and 20˚c or less

-seed quality maintained for a year

2. Hermetic storage

-seeds sealed in moisture resistant containers

-metal containers are used when very long storage periods are desired.

-before sealing the ambient air in the container may be replaced with an inert gas (argon or nitrogen).

3. Containerized seed storage

-seeds are maintained in specially constructed rooms, equiped with dehumidifiers and other environmentally control systems

-sometimes a desiccant is used to control the level of humidity

PROCCESSING

• Traditional Millstone for Grinding Maize

-Operating a millstone of this kind needs 2 - 3 people. It has a capacity to grind 4 - 5 kg of maize grains at one time. The maize flour is used for making various kinds of cake. Maize which is not so finely ground is eaten mixed with rice, beans and other foods. It is also used to make sweet soy sauce.

•         Pedal-Driven Maize Grinder

-The weight and installation area of this machine are only 1/5 those of the millstone. Its structure is simple, and a man of average health can operate it .The operating capacity is the same as that of the millstone, and so is the production of maize flour.

•         Improved Pan to Steam Maize

-This improved pan is made of cast iron. Inside the pan, there is an iron funnel which channels the steam into the maize flow, thus creating a kind of dough. Using the pan, each batch of maize requires only two hours to be steamed, and uses 40% less firewood than the conventional steamer.

•         Cake Toasting Mold

-This iron mold can be used to press and toast various kinds of cake, made either from maize flour or from a mixture of maize and other flours, mixed with other ingredients and seasonings to make a high-value product. Toasted cakes can be eaten immediately, or preserved for later use.

•         Small Mechanized Press

-One suitable press for farm households or small rural factories is the Eztrusion press. It has the capacity to process 20 - 25 kg of maize per hour. It is small, easy to operate and inexpensive. It gives a quick return on capital investment.

AGRONOMIC MANAGEMENT

•         Temperature

-minimum temperature for germination 10˚c and 20˚c

-average daily temperature of at least 20˚c for adequate growth and development

-optimum temperature 25˚c-30˚c

-temperature above 35˚c reduces yields

-frost not tolerated

-at temperatures above 45˚c or below 6˚c photosynthesis comes to a stand still

-should receive the necessary heat units in order to complete growth and therefore develop from one stage to the next

-base temperature is 10˚c

•         Water

-in the tropics maize does best with 600-900mm well distributed rainfall during the growing season.

-initially rainfall requirement is low but builds up to a maximum during the flowering period.

-thereafter the moisture requirement progressively decreases until the plants are physiologically mature

-critical stages of water requirement are seedling stage, knee-height stage, tasselling, silking and grain filling stages.

-moisture requirement is at its highest approximately 2 weeks before and after pollination as pollen is pure protein and thus require a lot of energy for its production

-water shortage for even 2 days of tasselling and silking can reduce maize yields to about 20% and 6-8 to about 50%.

-period of drought stress during vegetative stage results in smaller plants.

-a vigorous growing maize plant requires about 2-3 litres of water per day during peak growing period or an average consumptive use of water varies from 2,5 to 4,3mm per day.

-under high plant populations the requirement can be 10mm or more per day but is determined by prevailing temperatures, humidity and airflow.

-good moisture management is improved by ploughing in organic matter, breaking up any compaction layer and correct scheduling of irrigation.

-when irrigating irrigation should continue until 80% of all the outer cob leaves have turned brown.

-at this stage all cobs will be physiologically mature and no moisture is needed for grain filling.

SOILS

-can be grown on soils with pH of 5-8 but 5,5-7 is optimal

-does not tolerate water logging and is sensitive to salinity

-soils should allow optimum root development

-hybrids that can tolerate acid soils exist although no hybrid is resistant to soil acidity

-maize is best adapted to well drained sandy loam to silty loam soils

-will not thrive well on heavy clays

-the majority of tropical soils are acidic an aluminium toxicity is the most important reason for crop failure in such soils.

-on acid soils liming is important and can also supply the essential elements of ca and mg.

SOIL FERTILITY

-low fertility of most tropical soils reduces maize yields.

-maize responds well to fertilisers

-N is the most limiting nutrient in the tropics and provides the major difference between low and high input agriculture.

-N uptake is slow during the first month after planting but increases to a maximum during formation of the inflorescences.

-high nitrogen levels should be applied in 2 doses, the first dose at planting or 2 to3 weeks after emergence and the second one about 2 weeks before flowering.

Yield potential t/ha	2	3	4	5	6	7	8	9	10
Nitrogen potential kg/ha	20	45	70	95	120	145	170	195	220

(Pannar seed limited).

-the higher the yield target the more N per tonne of grain is required.

-Ph is the second most limiting and is immobilised by Al and Fe in acid soils and by Ca and Mg in calcareous soils.

-phosphate is not taken up easily by maize and many tropical soils are deficient in available phosphate.

-fertiliser is applied by band placement or broadcast with band being economical and efficient way of limiting fixation of nutrients.

-the exact amount of fertiliser that has to be applied to the soil will depend not only on the plant requirement of individual nutrients but also on how much of them the soil can supply.

--a general recommendation: apply 120kgN,60kg P2O5, and 40kg K2O per hectare for hybrids and 80kg N and 30kg P2O5 and 20kg K20 per hectare for composites.

-advisable to apply OM before ploughing to improve soil structure and supply nutrients.

-about 10-15 tonnes of well rotted OM in the form of farmyard manure or compost can be added before

	Wkly requirements as % of total need
	N%	Ph%	K%	Water %
EMERGENCE	LESS THAN 1	LESS THAN 1	LESS THAN 1	LESS THAN 1
1 WK	“	“	“	1
2 WKS	“	“	1	2
3 WKS	2	1	3	4
4 WKS	7	2	9	5
5 WKS	11	4	16	7
6 WKS	14	7	21	10
7 WKS	15	10	20	11
TASSELLING	16	11	13	12
SILKING	12	15	8	12
10 WKS	10	13	5	11
11 WKS	6	11	1	8
12 WKS	4	9	-K	6
13 WKS	2	8	-K	5
14 WKS	LESS THAN 1	5	-K	3
15 WKS	“	2	-K	2
16 WKS	“	1	-K	1
17 WKS	“	LESS THAN 1	-K	LESS THAN 1
MATURITY

 

ALTITUDES

-can be grown from lowland wet tropics to over 3500m altitude.

-found from sea level to 3700m above sea level from 55˚ N to 45˚S.

COMMON WEEDS

-Sensitive to weed competition during the 1st 4-6 weeks after emergence.

-in case the weeds are not controlled at the right time, there is 50-60 % reduction in yield.

-2 or 3 manual weedings needed.

-hand hoes, spades, cultivators

-cynodon dactylon, eluesine indica, sataria glauca, cyperus rotundus, sorghum halapense, commelina benghalensis, solanum nigrum, striga species (parasitic witch weed).

MAIZE DISEASES

-maize is subjected to as many as 112 diseases on a global basis

•         Fungal

-stalk rots (diplodia maydis, erwinia caratova), leaf blights (bipolaris maydis), downy mildew (peronosclerospora sorghi), smut (ustilago maydis), rusts (puccinia sorghi), grey leaf spot (cercospora zeae maydis), diploid cobrot/stem rot (stenocarpilla maydis), giberella ear and stem rot (fusarium graminearum).

-can be controlled byfield sanitation, crop rotation, use of resistant varieties, destruction of plant debris by burning or deep ploughing, spraying fungicides and seed treatments with fungicides

                                            Fusarium cob rot

                                      Diplodia cob rot

 

common rust                                                                

                           leaf blight

• bacterial diseases: bacterial stalk rots (erwinia species), bacterial leaf streak and spots (xanthomonas campestris), bacterial stripe (pseudomonas andropogonis).

-can be controlled by crop rotation, spraying, burying or burning debris

• viral diseases-maize streak virus (MSV), maize dwarf virus(MDV), sugarcane mosaic virus (SCMV), maize chlorotic mottle virus (MCMV), guinea grass mosaic potyvirus (GGMV),maize eyespot virus (MESV), maize mosaic rhabdovirus (MMV), maize mottle/chlorotic stunt virus (MMGSV) and maize stripe tenuivirus (MStpv).

-can be controlled bydestorying alternative hosts of vectors, spraying chemicals for control of vectors and using resistant or tolerant varieties.

MAIZE NEMATODES

-root knot nematodes :( meloidogyne incognita, m.javanica, m.chitwoodi), lesion nematodes (pratylenchus penetrans, p.thornei, p.zeae), lance nematodes (hoplolaimus galeatus), stunt nematodes (tylenchorhynchus dubius), stubby root (paratrichodorus minor).

-can be controlled by crop rotation and trap crops and systematic insecticides.

MAIZE PESTS

-cutworms(agrotis sp), stembores and stalkbores(B.fusca, E.saccharina), cob borer(mussida nigrivenella), cotton bollworm(helicorvepa armigera),armyworm(helicorvepa armigera), leafhoppers (cicadulina sp),grasshoppers(zonocerus variegurus),wirewom ,stinkbug(E.servus), corn leaf aphid(R.maidis) and storage pests like grain moths(S.cereala), grain weevels(sitophilus sp), larger grain borer(P.trucutus).

-can be controlled by using resistant or tolerant varieties, trap crops, insecticides and use of natural enemies.

 

HARVESTING

-in general harvesting takes place 10-15 days after grain has reached physiological maturity (when the process of nutrient uptake into kernels is over).

-indication of maturity are yellowing of the leaves, yellow dry papery leaves around the cobs and hard grains with glassy surface resistant to scoring with the thumbnail and glassiness depending on variety.

-in the dry season maize is often left in the field until the moisture content has fallen to 15-20%.

1. Hand harvesting

-small scale farmers harvest by hand.

-to harvest maize by hand, the ears are pulled from the stalk of the plant and no tool is used.

-Indicatively, the average duration of a manual maize harvest varies from 120 to 200 man-hours ( 15-25 man-days) per hectare.

-shucking the ears, that is, the removal of the husks covering the ears, may be done by hand or by machine at the same time as the harvest.

-If this operation is done by hand, it requires about 130 man-hours (about 16 man-days) per hectare.

-hand harvesting of maize is considered practicable for crops of under 12 hectares, if climate and availability of labour permit

-The work capacity of these machines varies from 1.6 to 3.45 h/ha, with

75 to 80 percent of the ears completely shucked, and total grain losses lower than 4.5 percent.

-two operators - a driver and a worker - are generally necessary to run

these machines.  use of one-row corn-pickers is economically

advantageous for harvesting a minimum of 2530 hectares a year; for

two-row machines the minimum harvest should be 30-60 hectares.

-corn-shellers resemble corn-pickers but have a device for shelling and

cleaning grains. These machines can thus simultaneously harvest,

shuck and shell the ears and pre-clean the kernels.

-sometimes coupled to a trailer for transport of the harvested grains,

one- or two-row corn-shellers can be tractor-drawn or carried.

-the self-propelled type, capable of harvesting two, three, or four rows,

is, however, the most widespread, since its performance is superior to

that of the tractor-drawn models described above.

-the work capacity of these machines is comparable to that of corn-pickers,

with grain-losses lower than 3 or 4 percent.

-another machine that is capable of simultaneously harvesting, shucking,

shelling, and cleaning maize is the combine-harvester.

-this machine is derived from a combine-harvester for wheat on which

modifications have been made to the cutting apparatus and the threshing device.

-although the work capacity of these machines depends on harvesting

conditions and on the size and shape of the parcels, it can run from 0.8

to 1.2 h/ha for six-row machines processing the whole plant, and from

0.4 to 0.6 h/ha for six-row machines treating only the ears.

-overall grain losses, usually caused by the cutting device, are rarely higher than 3 percent.

-two operators are generally needed for these machines.

-the use of combine-harvesters, like that of corn-shellers, offers an economic advantage for harvests of a minimum of 40-75 hectares a year.

PRODUCTION AND TRADE

-according to FAO estimates, the average world production of maize from 1999-2003 amounted 611 million t/yr from 139 million hectares.

-leading producers of maize globally are

1.USA -243 million t/yr from 28million ha

2.China -117million t/yr from 24 million ha

3.Brazil -38 million t/yr from 12 million ha

4.Mexico -19 million t/yr from 7 million ha

5.France -15million t/yr from 2 million ha

6.Argentina -15 million t/yr from 3 million ha

 7. India -12 million t/yr from 7 million ha

8.South Africa -9,4 million t/yr from 3,6 million ha

-maize production from tropical Africa in 1999-2003 was 26,6 million t/yr from 21,1 million hectares.

-the main producing countries being

1.Nigeria -4,7 million t/yr from 4,2 million ha

2.Ethiopia -2,9 million t/yr from 1,6 million ha

3.Tanzania -2,6 million t/yr from 1,6 million ha

4.Kenya -2,5 million t/yr from 1,6 million ha

5.Malawi 2 million t/yr from 1,5 million ha

-from 1961 to 1965 to 1999-2003 the annual maize production in tropical Africa increased from 9,1 to 26,6 million t/yr and the harvested area from 10,2 to 21,2 million ha.

-average world export of maize amounted to 80,1 million t/yr in 1998-2002 with

1.USA -47,5 million t/yr

2.Argentina -10,3 million t/yr

3.France -7,9 million t/yr

4.China – 7,4 million t/yr as the main exporters

-exported maize from tropical Africa was only 307 000 t/yr with

1.Zimbabwe -143 000 t/yr

2.Tanzania – 42 000 t/yr

3.Uganda – 25 000 t/yr as the main exporters

-the main importers were

1.Japan – 16,3 million t/yr

2.South korea – 8,3 million t/yr

-maize importers into tropical Africa were 1,8 million t/yr

RESEARCH DONE ON MAIZE IN BOTSWANA

1. Department of agricultural research, Botswana

•         phosphate and kraal manure experiment in Lobatse

-use of kraal manure alone was highly significant than mixture of kraal manure and P and P alone.

•         Effect of seasonal rainfall on maize

-maize in Botswana is largely dependent upon rainfall received in february and march each year ie during flowering period

•         Mahalapye spacing trials

-maize is best spaced at 30” intervals in rows 36” apart.

-in dry areas slightly wider spacing will give higher yields

•         Nitrogen fertiliser experiment

-N in form of 100lbs of ammonium sulphate or as 1 ½ tonnes of kraal manure per acre gave significant increase in maize yields at Lobatse.

•         Maize hybrid evaluation trial

-the grain yield recorded showed that some hybrids such as PNR 473, SNK 2154, PAN 6146, and PAN 6578 have good potential in Botswana under dryland farming.

•         Early maturing experiments

-23 early maturing genotypes some regional and local check variety which was KEP.

-average yield shows that regional check R201 was superior to other genotypes with the average yield of 4684kg/ha.

•         Intermediate to late maturing hybrids yield trials

-an open pollinated variety had the lowest yield when compared to the hybrids.

-KEP performed in a simillar manner to the hybrids

•         Effect of timing and rate of Nitrogen supplied to maize in Pandamatenga vertisols

-maize grain yield was significantly increased by Nitrogen application while splitting the applied Nitrogen increased Yields by 17%.

•         Green mealies

-4 green mealies variety trials were conducted at Sebele and Bobonong

-R201,PNR 473,produced the highest yields while other varieties produced lower but similar yields

-varieties R 01,TX 9, AX 305W, SNK 2151 and A1257N produced larger cobs while SNK 220 produced the smallest cobs

•         Control of maize stalk borer (insect control trial)

-carbofuran provided the most satisfactory control of stalkborer than trichlorfon and carbaryl but all the insecticides were found to have brought about significant reduction in stalkborers

•         Effect of tie-ridging and manure on yield of maize

-tie-ridging and manure did not improvr maize yields

-plant stand at harvest revealed that adding no manure and tie-ridging increased plant stand

•         Effect of variety and plant population on yield of maize

-KEP*PHIJ-6-94, KEP*PHEB-7-94 were compared with KEP in various plant population

-no significant difference in yield

-plant variety interaction was not significant

  -KEP responded well to recommended plant population of 65000 plants per hectare compared to 40000 plants.

WHAT NEEDS TO BE DONE

-Nitrogen fixation in maize and increased N capture by roots

-improved P use efficiency and tolerance to acid soils

-tolerance to salinity.

-recover from water stress once water is available

-increase the efficiency with which the plant partitions photosynthates to the grain while keeping the biomass unchanged. This can be done by reducing plant height/size through use of dwarfing genes. can also be done by producing early flowering cultivars coupled with fert, pest control and irrigation which allows the plant to allocate assimilates to seeds sooner thereby leading to reduced accumulation of reserves in leaves.

-increase photosynthetic efficiency by eliminating the limiting factors of photosynthesis which are low sunlight interception, water stress, pest and weeds by leaf orientation and breeding for drought and pest and weed tolerant cultivars

-more water use efficiency to produce more yield with minimal rainfall

-shorter lifecycle in order to produce grain before rains are scarce

-resistance or adaptation or tolerance to heat.

MAIZE POTENTIAL IN BOTSWANA

-maize is a staple food in Botswana

-one of the main sources of energy

-give the highest yield per man hour invested as compared to other cereals.

-first crop to be harvested for food during the hunger period especially as green mealies.

-easy to grow as a sole crop or intercropped with other crops

-east to harvest

-does not shatter and is not liable to bird damage

-many uses as food(papa,porridge,roasted) and in industries

-source of income for smallholder farmers and traders

 

-maize imports are increasing which shows a growing demand for maize and its products.

-shows that local production is not meeting the population demand for maize.

-production fluctuates according to seasons/yrs and this goes hand in hand with the area harvested.

-yield/ha is constant

-maybe caused by farmers still using substandard traditional ways of production like

-little or no use of fertilisers, no use of herbicides or pesticides, no

irrigation since water is a limiting factor, use of varieties which are not

high yielding under semi arid conditions.

-lack of technologies as many maize technologies have been developed in national and international research stations in Africa but most of these are not yet adopted by farmers.

-short supply of high quality seeds because of lack of

-as demand is increasing and yield/ha is not increasing, there is need to increase yield in order to reduce the amount of imported maize and so reducing total expenditure.

-this can be done by

-farmers improving access and use of fertilisers and crop protection chemicals-herbicides and pesticides.

-using cultivars and cropping techniques that fit well into prevailing cropping systems.

-having farmers shifting from small scale to large scale production where the benefits of irrigation and adopting high technologies are high

-use of high breeds that tolerate to a greater extend the adverse effects of heat and drought stress.

-eliminating gaps between researchers and farmers so that research results are conveyed to farmers

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