Willem Kilian Research Team Leader
Dr Annelie Barnard Snr Researcher
Hesta Hatting Research Technician
VisserSnr Research Technician
Dr Ernest Dube Snr Researcher
Hellen Mopeli Research
Ben van RensburgIrrigation Technician
The long term objective of the cultivar evaluation programme is to scientifically determine and evaluate the adaptation, yield potential, yield stability, quality and agronomic characteristics of all released small-grain cultivars in all the production regions of South Africa.
In order to supply producers with reliable, objective and scientific data, three cultivar adaptation programmes are conducted in the three different wheat production areas of South Africa, aimed at determining the best adapted variety for a specific production region. After receiving high-yielding varieties with good yield stability, excellent agronomic characteristics, superior grain quality, as well as with resistance to pests and diseases, from all the various seed companies and organisations, these varieties are compared in trials and the best suited varieties are then recommended for cultivation in a specific production region.
The results are used to make recommendations to producers and other role-players in the industry through the two very comprehensive "Guidelines for small grain production in the winter rainfall region" and "Guidelines for small grain production in the summer rainfall region", farmer's days, advisor's days, scientific congresses, etc. This programme is a unique service of its kind in South Africa.
Sprouted wheat spike
Germination of wheat within the grain head before harvest is called pre-harvest sprouting (PHS). Periods of prolonged rainfall and high humidity after the grain has ripened and before it can be harvested can contribute to PHS, which can be thought of as a premature germination. Germination can begin as a wheat kernel absorbs moisture and swells. Visible indications of PHS include kernel swelling, germ discoloration, seed-coat splitting, and the root and shoot emerging.
Alpha-amylase enzymes are produced to reduce the stored starch granules to simple sugars that can be used by the new plant. Wheat that has been subjected to amylase activity is not suitable for bread baking purposes. The amount of sprouting measured in a certain sample is directly correlated with the Falling Number (FN) test. A low FN (< 220s) is not suitable for bread baking.
The inherent dormancy of all commercially released wheat cultivars, as well as the breeding material from ARC-Small Grain Institute is evaluated in a rain simulator for their ability to resist germination under PHS conducible conditions.
This screening method is a laborious process. The scores determined are influenced by a number of environmental factors and should not be interpreted as predicting the likelihood of PHS in a particular year. However, relative differences among cultivars are representative of differences that exist when exposed to similar conditions. Some cultivars are less likely to develop PHS and may tolerate greater weathering prior to harvest.
The meganisms associated with sprouting tolerance are very complex and not easily manipulated. To ensure that only sprouting resistance cultivars are being released into the wheat market, all ARC-SGI breeding material are evaluated for their sprouting tolerance.
As the kernel matures, it starts to germinate and sprouting occurs
Low HFN wheat is not suitable for bread baking
Seed plays a vital role in the potential crop yield of each small grain producer. Small grain seed must comply with legal requirements with regard to the purity and germination percentage before it can be marketed. The Small Grain Institute now has a registered Seed Testing Laboratory that uses international methods (viz. ISTA methods) to determine the quality characteristics of seed. This ensures that results are generally accepted by buyers and sellers of seed. Tests that can be done by the laboratory include the following:
Our aim is to provide an objective and reliable service to all clients.
More information on tests or costs can be directed to Hesta Hatting (058-307 3417).
The cost of fertiliser is a substantial proportion of the total production cost of wheat and the optimalisation of fertilising practices is therefore of the utmost importance.
The development of specifically adapted cultivars over the past few years has necessitated the planning of a fertilisation programme by the producer on an annual basis. As with cultivar choice, a fertilisation programme is planned on the basis of a specific yield potential or target yield. The following guidelines can be used as a reference to plan such a programme for a given situation.
Reliable soil analysis data is essential for planning an effective fertilization programme. The regular sampling of lands to timeously identify problems, such as soil acidification, is absolutely essential.
Soil sampling for analysis
Soil is analysed to determine its ability to supply the necessary plant nutrients to the crop concerned. Soil analyses are related to potential nutrient uptake, supplementation of plant nutrients through fertilisation and the target yield. From plant nutrient research programmes that take these factors into account, guidelines that will be valid in a given situation are laid down.
Therefore, to make the best possible use of these guidelines, it is essential that the soil samples that are interpreted are representative of the particular land. To achieve this, the following standard procedures are required when handling soil samples:
• Homogeneous units that are also practical for crop production purposes must be sampled. (Homogeneity is determined by previous crop performance, topography and the soil depth, colour and texture).
• A soil sample must represent a homogeneous unit of not more than 50 ha.
• Homogeneous units must be numbered clearly and separately.
• Problem/poor patches must be indicated and sampled separately.
• When taking the sample, all foreign matter (grass, twigs, loose stones) must be removed at the sampling point. In the case of very rocky soils an estimate must be made of the rock percentage per volume.
• Twenty to 40 samples must be taken at random over the entire area of each homogeneous unit of the land. Conspicuously poor patches, headlands, places were animals gather, et cetera, must be avoided.
• The recommended depth for sampling the topsoil is about 200 mm, in other words the 0-200 mm portion of the topsoil is sampled.
• Subsoil samples must be taken from the 300-600 mm layer of the profile for dryland cultivation, and at 300-600 and from 600-1 200 mm for irrigation.
• If the land has been ploughed, random samples must be taken from the entire area. If the rows of the previous crop are still visible, the samples must be taken randomly between and in the rows.
• To compare results, sampling should be done at more or less the same time of the year every year, or during the same phase of the cultivation programme, but at least once every 3 years.
• The 20-40 samples from which the final sample is to be compiled must be collected in a clean bag. (Farmers are warned against using salt bags, fertiliser bags or other contaminated containers). Clods must be crushed, foreign matter removed, and the soil must be mixed thoroughly. After spreading the soil in a thin layer, small scoops are taken evenly over the whole depth and area and placed in a clean plastic bag or carton. This final sample, representative of a homogeneous unit, must have a mass of 0,5-1,0 kg.
Additional information about the properties of the soil, climate, as well as the production and fertilisation history should also be furnished, since recommendations cannot be based on soil analysis alone. The Soil Laboratory at ARC-Small Grain Institute offers free sample boxes and fertiliser recommendations for wheat. The laboratory can be contacted for further information at 058-307 3501.