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Maize varieties: Telling them apart
Different maize varieties have different traits and yield performances that the farmers should take note of. PHOTO BY LOMINDA AFEDRARU
What you need to know:
This is because seedlings will be generated from already planted cassava stock and banana suckers
Maize farmers require varieties appropriate to their anticipated level of investment in inputs and with high probability of producing good grain yield.
The yield may not necessarily be determined by the various varieties but farmers may need to consider biotic factors like pests and diseases and abiotic factors such as drought, flooding and soil erosion.
It is, therefore, pertinent for the farmer to carefully select varieties that he or she would wish to grow depending on these factors that may affect the yield. There are open pollinated and hybrid maize varieties that farmers can choose to grow.
Costs and yields
Agricultural experts usually encourage farmers to grow hybrid varieties because they are high yielding. But this comes with a cost of purchasing seed each planting season.
Likewise planting open pollinated varieties (OPVs), which are the traditional varieties, also comes with a cost. A farmer expecting to harvest better yield will not achieve his or her dream because the yields will be lower.
Dr Geoffrey Asea, who heads cereals programme at National Crop Resources Research Institute (NaCRRI) Namulonge, explained the characteristics and methods of breeding hybrids during a recent Open Forum on Agricultural Biotechnology (Ofab) held in Kampala.
He pointed out that hybrid varieties existed since 1926 in US. In Africa, it is since the 1960s.
The first varieties were bred in Uganda in the late 1960s by British scientists who after leaving the country did not reserve these maize varieties for future use.
Keep the traits
Hybrid maize varieties resurfaced in 1972 bred by Patrick Rubaihayo, professor emeritus at Makerere University, which were not preserved. In 1980s, there was foundation seed available for hybrid maize. Since then, scientists have been releasing various varieties mainly for disease and pest resistance, drought tolerance and high yield vigour.
Hybrid plant varieties are a result of crossing parental traits of two individual plants using conventional means. One can cross a single parent to another single parent but somebody may prefer to cross two or more parents.
Single parent crossing gives more yields compared to double and triple parent crossing but hybrid maize variety obtained from single crossing like Longe 2H is expensive. This is because the seeds are much smaller compared to the rest meaning more seeds would be required to weigh 1 kg.
It is advisable to make the crossing once because the traits will disintegrate when you keep crossing to obtain the same variety.
Single crossed varieties also grow uniformly with same height and cob size. Usually, the seed multipliers are advised to choose pure lines with same seed size to obtain the best hybrid variety. But farmers are advised to purchase varieties that yield well in the different geographical locations.
Details given by Dr Asea indicate: In the eastern region where the rains are short, Longe 10 H variety gives good yields. In Masindi, farmers are advised to grow Longe 7H, 8H and 9H. For areas lying between highlands like Fort Portal and Bulambuli, hybrid varieties like UH6303, FH6150 and Longe10H do best.
For farmers in Kapchorwa District where the weather enables maize to grow in a period of five months or more covering one season only, varieties bred from Kenya such as H614 and H628 are advisable.
Simultaneous release
The statistical explanation is that a farmer growing OPVs will harvest 5 tonnes per hectare compared to 10 tonnes per hectare from one with a hybrid variety.
OPVs are left to pollinate naturally either through wind blowing the pollens or transfer by insects like bees.
A farmer who recycles hybrid maize seed in his farm will experience a 30 per cent yield loss because of the disintegration in the parental make up.
Farmers and seed companies growing hybrid maize varieties for business are required to cut off tussles of the plants meant to be female to enable pollination to occur. For the maize plants that are meant to be male, the flowers from the shooting maize cob should be removed.
It is important to ensure that the male and female parts of the plant shoot at the same time. This can be done through nicking, which means simultaneous pollen release from the male and female parts.
Value and vigour
Crossing of hybrids applies to all plants such as soybean, passion fruit, green vegetables, rice, coffee, sorghum, and millet.
There is a difference between hybrids and genetically modified (GM) crops. For the latter, a particular gene is picked from a plant and transferred to another plant to solve a specific challenge like pest and disease infection. This is done in the laboratory.
For hybrids, the crossing is done conventionally with all the traits of the plants where crossing is exercised.
In case of maize, most GM maize varieties tested are hybrids. This, according to Dr Asea, is to maintain the high yielding vigour.
If a researcher combines high value hybrid to a high value trait, the result will be obtaining a plant with high yield vigour but not all hybrids are GMOs.
Put in one basket
Dr Thereza Ssengoba, from Programme for Biosafety Systems, noted that 35 per cent of maize seed in Uganda are hybrids with the rest being OPV.
Scientists are breeding crops, animals and poultry using various technologies. These methods include conventional breeding, traditional biotechnology, molecular marker, tissue culture and modern biotechnology.
Globally, scientists are putting these products in one basket and it is upon the farmer to choose what he or she prefers.
In breeding GM crops, research has to start from the laboratory and taken through the green house and eventually confined field trial, which is not case where other technologies are applied.
In the case of Uganda, for GM maize, the frequency for purchase will arise from hybrids which will not be recycled by farmers. For the vegetatively propagated GM cassava and GM banana, farmers will recycle it just like how they have been doing with the conventional varieties. This is because seedlings will be generated from already planted cassava stock and banana suckers.
