Advanced Search Abstract Further improvements to wheat yield potential will be essential to meet future food demand. As yield is related to the number of fertile florets and grains, an understanding of the basis of their generation is instrumental to raising yield.
Remember, Haun scale values from the booting to ripening stages are dependent on the number of leaves Anthesis in wheat on the main stem.
The example given here is for a plant with eight leaves on the main stem. The Feekes scale recognizes eleven major growth stages starting with seedling emergence and ending with grain ripening Table 1.
The Feekes scale is frequently used to identify optimum stages for chemical treatments, such as fungicide applications, that focus on the plant development period from the start of stem elongation Feekes stage 6 to the completion of flowering Feekes stage The Zadoks scale provides the most complete description of wheat plant growth stages Table 1Figure 1.
It uses code based on ten major stages that can be subdivided, making it particularly suited for computerization. When using the Zadoks scale, the main growth stages, e. However, a consideration of temperature is also important in these discussions because temperature determines the rate of growth and development.
Heat units have been chosen as the measure of thermal time in this discussion to avoid confusion between growing-degree days and calendar days. Heat Units The thermal time required for crop production is determined by adding the daily heat units together for the period between planting and harvest.
When the centigrade temperature scale is used, the heat units generated each day is determined by adding the minimum and maximum daily temperatures together and dividing by two.
Thermal Time Requirements For Wheat Production The heat unit requirements to produce a mature crop are approximately for spring and for Anthesis in wheat wheat.
As we all know, there are large variations in temperature from day to day and growing season to growing season. The use of thermal time rather than calendar time takes this variability into consideration and provides an explanation for differences in crop maturity when observations from different years are compared.
For example, we harvested Norstar winter wheat on July 20 in and August 24 in at Saskatoon. The growing season was much warmer with the result that the thermal time requirements to produce a mature Norstar crop were met five weeks earlier in than in Wheat growth and developmental stages according to the Zadoks scale.
See Table 1 for comparisons with Feekes and Haun scales. Development of the roots, leaves, tillers, and spikelets on the head of the wheat plant takes place in an orderly, predictable pattern that is dependent upon thermal time. It takes approximately heat units for a wheat plant to germinate and emerge from a seeding depth of less than one inch 2.
The appearance of each successive leaf on the main shoot and tillers then proceeds at a constant rate that is determined by cultivar, sowing date, and latitude. Most wheat cultivars require between 80 to heat units to produce each leaf on the main shoot.
After the requirements for leaf development have been met, another heat units are normally required to complete the heading and maturation stages. The Wheat Kernel The mature wheat kernel caryopsis is composed of approximately 83 percent endosperm, Once germination starts, the endosperm provides the developing plant with an energy source until its roots are established and newly expanded leaves allow it to harvest energy from the sun.
The embryo of the mature wheat kernel has already undergone the first stages of plant development before the kernel is separated from the parent plant.
In a mature kernel the embryo includes the coleoptile, which protects the first leaf as it pushes its way through the soil to the surface during germination, the radicle, which becomes the first root, and primodia, which develop into the first three leaves and seminal roots.
Germination Germination starts with the uptake of water imbibition by a wheat kernel that has lost its post-harvest dormancy. Plant development is resumed once the embryo is fully imbibed. With the resumption of growth, the radicle and coleoptile emerge from the seed Figure 2.
The first three seminal roots are produced and then the coleoptile elongates pushing the growing point toward the soil surface. Seedling Stage The seedling stage begins with the appearance of the first leaf Figure 3 and ends with the emergence of the first tiller.
Up to six seminal roots and three leaves support the plant at this stage. The crown of the plant usually becomes noticeably distinct after the third leaf has emerged Figure 4.
Wheat seedling with three leaves and a developing crown. A wheat plant with five leaves, two tillers, and a well developed crown. Tillering Stage Crown formation is soon followed by the appearance of tillers and development of a secondary or crown root system Figure 5.
The crown root system provides the plant with most of its nutrients and water during the growing season. The distance between the wheat kernel and the crown is determined by the length of the subcrown internode Figure 4.
The subcrown internode can elongate several inches and, depending on soil temperature, usually positions the crown within 1.Anthesis definition, the period or act of expansion in flowers, especially the maturing of the stamens.
See more. Anthesis definition, the period or act of expansion in flowers, especially the maturing of the stamens. See more. Wheat and barley response to post-anthesis warm nights was evaluated under field conditions.
• Grain weight was reduced by 3% per °C of night temperature increase, causing a yield reduction of 4% per °C. In the wheat crop, there is a close relation between the number of kernels per unit area and the ratio between incoming radiation to the mean temperature above °C (the photothermal quotient) calculated for the 30 days preceding anthesis (Fischer, a).
North Dakota research has shown that the best chance of protein enhancement of spring wheat and durum is accomplished by waiting until the end of flowering (post-anthesis) and broadcasting 10 gallons/acre of 28 percent mixed with 10 gallons/acre of water over the wheat in the cool of the day.
Anthesis is the period during which a flower is fully open and functional. It may also refer to the onset of that period. The onset of anthesis is spectacular in some species. In Banksia species, for example, anthesis involves the extension of the style far beyond the upper perianth parts.