it explains brief information on phenological studies at different growth stages of wheat

1. UNIVERSITY OF AGRICULTURAL SCIENCES
DHARWAD
Course title: Agronomy of major cereals and millets [AGR-506]
(2+1)
Presentation topic:-Phenological studies at different growth
stages of wheat
Submitted by:-
Suresh Jambagi
Sr. MSc(Agri),Entomology
PGS18AGR7711

2. WHEAT
 Genus- Triticum Family- Gramineae
 Origin= Mediterranean region or S-W Asia (Turkey)
 C3, Long day plant.
 First cultivated around 9600 BC.
 Cultivated wheat Triticum aestivum is an allohexaploid (2n=6x=42).
 Staple food of about 35% of world population.
 Contains spongy protein i.e Gluten (colloidal complex of gliadine and
glutenin) essential for baking
 Considered as ‘Versatile cereal food’.
Area Production
WORLD 222.68Mha 756MT
INDIA 30.79Mha 98.51MT
KARNATAKA 1.74 Lakh ha 1.56 Lakh tons

3. Classification
1. Diploid wheat (2n)= 14 chromosomes
2. Tetraploid wheat (2n)= 28 chromosomes
3. Hexaploid wheat (2n)= 42 chromosomes
1.Einkorn wheat (2n=14) – Triticum monococcum (cultivated)
2.Emmer/ Khapli wheat (2n=28) – Triticum dicoccum (cultivated)
Triticum dicoccoides (wild)
3.Durum/Macaroni wheat (2n= 28)- Triticum durum
4. Bread wheat (2n=42)- Triticum aestivum

5. GROWTH STAGES OF WHEAT
I. Pre-establishment stages
1. Pre-emergence- Germination of seeds, which produces seminal roots
and coleoptiles.
2. Emergence- Germinating seeds produce coleoptile above the soil
surface.
II. Vegetative stages
3. Seedling- Young plants establish larger root systems in their seedling
stage.
4. Crown root stage- This coincides with three/four leaf stage of plant.
5. Tillering- Plant produces crown and branch out into tillers from their
base at soil surface.
6. Jointing- At this stage, the plants starts elongating when the nodes start
developing above the crown node.

6. III. Reproductive stages
7. Booting- The upper most leaf swells out into flag holding the spike into it.
8. Heading- The spike starts emerging out from the leaf sheath.
9. Flowering- Anthesis of florets and fertilisation of ovaries take place.
IV. Post-anthesis stage
10. Filling- After fertilisation, the ovaries start elongating in ovules or seed passing through
milk, soft dough and hard dough stages.
11.Maturity- At this stage, the colour of glumes changes and kernels become fairly hard.
12.Harvest

9. Growth stages of winter wheat (Waldren and Flowerday, 1979
Growth stage Description
0 Emergence of coleoptile
1 Crown is visible, tillers develop
2 Leaf sheaths elongate and forms a false stem
3 Culm elongation. First internode visible (jointing)
4 Top of flag leaf visible (Boot stage)
5 Peduncle elongates. Inflorescence emerges (heading)
6 Flowering (anthesis)
7 Anthesis complete. Grain filling begins, lower leaves change colour
8 Grain is stiff dough. Flag leaf has lost green colour
9 Ripening. Grains hard but will not crack. Inflorescence lost green
colour. Uppermost node still green
10 Maturity. Grain cracks and is easily separated from chaff.

10. Phenology of wheat:
 Organ differentiation defines the various stages of wheat development.
 Physiologically, the stages are usually distinguished as germination, emergence,
tillering, floral initiation or double ridge, terminal spikelet, first node or
beginning of stem elongation, boot, spike emergence, anthesis and maturity.
 These stages may be grouped into:
1. germination to emergence (E);
2. growth stage 1 (GS1) from emergence to double ridge.
3. growth stage 2 (GS2) from double ridge to anthesis.
4. growth stage 3 (GS3), includes the grain filling period, from anthesis to maturity.
NOTE:
* The time-span of each development phase essentially depends on genotype,
temperature, day-length and sowing date.
* Physiological maturity= The time when the flag leaf and spikes turn yellow (Hanft
and Wych, 1982).

11. I. Germination to emergence
 The minimum water content required in the grain for wheat germination is 35
to 45 percent by weight.
 Germination may occur between 4° and 37°C, optimal temperature being from
12° to 25°C.
 Seed size does not alter germination but affects growth, development and yield.
 Bigger seeds have several advantages when compared to smaller seeds, such as
faster seedling growth, higher number of fertile tillers per plant and higher grain
yield.
 During germination, the seminal roots grow first, followed by the coleoptile,
which protects the emergence of the first leaf.
 The length of the coleoptile limits sowing depth, and its length changes with
genotype, increasing only slightly when seeds are sown deeper.
 Semi-dwarf wheat has shorter coleoptiles than tall wheat.

12. II. Emergence to double ridge (GS-I)
 Floral initiation (double ridge) occurs at 20 DAS in spring wheat and 35 DAS in
winter wheat
 The duration of this stage (GS1) may vary from 60 to 150 days depending on sowing
date and genotype.
 Wheat tillers grow from the axils of the main shoot leaves.
 The potential number of tillers varies with genotype, particularly among flowering
types.
 winter types having a greater number.
 Semi dwarf wheats usually have a high number of tillers.
 Bud differentiation into tillers and tiller appearance generally end just before stem
elongation starts.
 Tillering does not end at any specific wheat development stage, but rather it is
controlled by a number of genetic and environmental factors. Longnecker et
al.(1993).
 Not all tillers produce spikes in wheat, and many tillers abort before anthesis.
 The number of productive tillers depends on genotype and environment and is
strongly influenced by planting density.
 Under favourable conditions, one and one-half fertile tillers per plant is a usual
number.

13. III. Double ridge to anthesis
 Wheat plants have 4 to 6 leaves in the main shoot when the
growing apex changes from the vegetative to the reproductive
stage.
 The glume and lemma primordium stages follow.
 The floret primordia are found in the axil of each lemma.
 Temperatures above 30°C during floret formation cause
complete sterility.
 Each spikelet has 8 to 12 floret primordia in the central part of
the spike.
 The basal and distal spikelets have 6 to 8 florets.
 Less than half of these florets complete anthesis; the rest abort
or are insufficiently developed before anthesis to be fertilized.

14. IV. Anthesis to physiological maturity
 The wheat spike contains only one spikelet per rachis node.
 Each spikelet has 3 to 6 potentially fertile florets, which are self-pollinated in
96 percent of the cases.
 Anthesis begins in the central part of the spike and continues towards the basal
and apical parts during a 3 to 5 day period.
 The proximal florets of the central spikelet are fertilized 2 to 4 days earlier than
the distal florets.
 These grains usually have a greater weight.
 After floret fertilization, cellular division is rapid, during which the endosperm
cells and amyloplasts are formed.
 This period is known as the lag phase and lasts for about 20 to 30 percent of
the grainfilling period.
 After there is a phase of cell growth, and differentiation and starch deposition
in the endosperm, which corresponds to linear grain growth and takes from 50
to 70 percent of the grainfilling period.
 The embryo is formed at the time of endosperm growth.

15. Days from emergence to physiological maturity in a spring and winter
wheat
Development stage
Time (days)
Spring wheat Winter wheat
Emergence 0 0
Floral initiation (double ridge) 20 35
Terminal spikelet 45 60
First node 60 80
Heading 90 120
Anthesis 100 130
Physiological maturity 140 170

16.  Wheat needs
Cool and moist weather –Vegetative period
Warm and dry weather – Reproductive stage
Vernalisation
 Vernalisation is the requirement to be exposed to cold temperatures in order for the
reproductive phase to begin.
 Temperatures in the order of 1° – 12° C are needed to meet this requirement depending on
varietal characteristics.
 Wheat varieties that have little or no vernalisation requirement are often referred to as
spring types, and temperatures in the range of 7 to 18° C for brief periods will be
sufficient for vernalisation.
 Wheats that have a strong vernalisation requirements are called winter types, and lower
temperatures of between 0° and 7° C for several weeks are needed for vernalisation.
 Vernalisation is a useful tool in that it gives an environmental cue to the plant on when is
the most suitable time to transform to the reproductive phase, and so offer a greater
sowing window.

17. REFERENCES:-
1. Agronomy of field crops – S R Reddy, Y. Reddi Ramu
2. Modern techniques of raising field crops – Chidda singh, Prem
singh, Rajbir singh
3. Botany of field crops- J.S Nanda and P.K Agarwal
4. websites