Anthesis stage of wheat
After emergence, all development stages are based on observations on the main shoot, usually the tallest and thickest. Figure 7. Spikelet number per spike is already determined at this stage, varying from 20 to 30 Allison and Daynard, ; Kirby and Appleyard, Spikelet development on the microscopic head is usually completed by the time the first node is 0. Heading Stage The heading stage extends from the time of emergence of the tip of the head from the flag leaf sheath to when the head has completely emerged but has not yet started to flower. Drought and heat stress during the stem elongation and booting stages increase the rate of tiller mortality by placing added restrictions on resource availability. Anthesis stage or flowering marks the beginning of grain setting and filling. However, as long as the crown remains alive, new roots and leaves can be regenerated. See Table 1 for comparisons with Feekes and Haun scales.
It uses code based on ten major stages that can be subdivided, making it particularly suited for computerization. Bauer, and J. Spike growth, slow in its early stages, increases greatly about the time the ligule of the flag leaf becomes visible Krumm et al.
Double ridge stage in wheat
Montana State Univ. The development of coleoptile tillers is not closely synchronized with the development of the rest of the plant, but their appearance often coincides with the emergence of the third leaf on the main shoot. So Zadoks 5. Notice that the drawing on the right of the illustration has two Z codes describing its four main stem leaves Z1. This period is known as the lag phase and lasts for about 20 to 30 percent of the grainfilling period. Depending on the weather and the variety, flowering usually occurs about days after full head emergence Feekes Lodging can lead to grain spoilage. The kernel accumulates most of its dry weight during dough development. Each tiller that is produced represents the potential for a wheat plant to develop an additional stem complete with its own leaves, roots, and head. Spikelet number per spike is already determined at this stage, varying from 20 to 30 Allison and Daynard, ; Kirby and Appleyard, The number of viable seeds planted and the number of tillers produced per plant sets the upper limit on the number of heads that can be produced by a wheat crop. Anthesis to physiological maturity The wheat spike contains only one spikelet per rachis node. Drought and heat stress during the stem elongation and booting stages increase the rate of tiller mortality by placing added restrictions on resource availability. Winter wheat plants must survive the many stresses of winter see Chapter
One problem is that this stage is not easily detected without dissection of the plant. The distance between the wheat kernel and the crown is determined by the length of the subcrown internode Figure 4.
For ex-ample, stages Z1. Some scope appears to exist for selecting genotypes with a reduced maintenance respiration, which normally uses 2 to 3 percent of the dry weight per day Robson,but its effect on radiation use efficiency would be low Loomis and Amthor, Environmental stress prior to flag leaf appearance can result in a loss of spikelets on the developing head Figure 7.
This description is often all you need. Each spikelet has from 8 to 12 floret primordia in the central part of the spike.
Notice that the drawing on the right of the illustration has two Z codes describing its four main stem leaves Z1. 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 Flowering or Anthesis Stage The flowering or anthesis stage lasts from the beginning to the end of the flowering period.
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