Ph.D Seminar

Seminar-2
on
Role of temperature stress in growth and
development of rice crop
Speaker,
Yasmeen Begum
Ph. D 2nd Year
ID No. PHD19AGR9011
Dept. of Crop Physiology
College of Agriculture, Raichur
UAS, Raichur-584104
Date: 21-05-2021
Time :12:00 PM
Role of temperature stress in growth and development
of rice crop

References
Conclusion
Case studies
Ripening stage
Reproductive stage
Vegetative stage
Effect of temperature on different growth stages of rice
Growth and developmental stages of rice crop
Stress overview
Introduction
Flow of Seminar:

Introduction:
 Importance of rice:
 Rice is an important cereal crop of the world. Considered as staple food of
over half of the world population.
 Is a C3 plant
 Primary source of food
 90% of the rice production is from tropical and subtropical Asia.
 Temperature stress has devastating effects on plant growth and metabolism, as
these processes have optimum temperature limits in every plant species.

 Exposure of plants to temperature stress leads to the
modification of metabolism.
 Plants try to adjust their cellular metabolism altered due to
rising or falling of temperatures.
 Low temperature severely affects the reproductive
development of rice crop at the time of anthesis which leads
to sterility in flowers.
 Low temperature during the reproductive stage causes
degeneration of spikelets, incomplete panicle exsertion and
increases spikelet sterility.
Continued…

Stress Overview
Stress
Biotic Stress Abiotic Stress
Drought Salinity
Temperature Metal Stress
High Temperature Low Temperature
Chilling
(0 - 15oC)
Freezing
(˂ 0oC)
Heat stress

Low Temperature Stress:
 In tropical and subtropical plants
Chilling injury occurs at 10oC to 25oC
 In temperate plants at 0 oC to 15oC.
Symptoms of chilling injury:
1. Surface lesions on leaves
2. Abnormal curling and crinkling of
leaves
3. Water soaking of tissues
4. Cracking and dieback of stems
5. Internal discolouration (vascular
browning)
 it occurs when plants are exposed
to a low temperature below 0 oC.
Freezing stress results in ice
formation within the plant tissues.
It will affects the several aspects of
plant growth viz., cell division,
photosynthesis, water transport etc.
Chilling stress: Freezing stress:

 Plants including maize, rice, soybean, cotton, tomato and banana are
more sensitive to temperatures below 10-15 °C and exhibit symptoms of
chiiling injury.
 The symptoms of stress induced injury in these plants appear from 48 to
72 hours, this duration varies from plant to plant.
 For rice pollen formation and cell division 23℃ temperature is required
for O. sativa and 20℃ temperature required for O. japonica.
Continued…

Physiological Reaction of Plants to
Low Temperature
1. Total water content of the cell decreases
2. Unsaturated fatty acid increases & saturated fatty acid decreases
3. ABA increases, GA decreases which leads to dormancy
4. Uptake of solutes by root decreases due to which water balance disturbed
5. Transpiration is more as compare to the water absorption due to that the plant
loss water which results in leaf curling
6. Photosynthetic rate decreases & rate of respiration increases
7. Organic substance get degrades

Effects of heat stress on growth
of rice crop
 Reduced germination
 Abnormal seedlings
 Poor seedling vigour
 Loss of cell water content
 Reduced net assimilation lead to
reduced relative growth rate
 Reproductive tissues are more
sensitive to heat stress
Pollen and spikelet sterility
Impaired pollen germination
 Reduced pollen viability
 Increased flower abortion
Impaired fruit and seed set
Effects of heat stress on
reproductive development
Splitting of locule
Ambient temperature
Heat stress

Morphological symptoms of heat stress on different crop species
Leaf senescence
Sun scald
Sun burn
Scorching of leaves

Mirza et al., 2013
Schematic illustration of the effect of temperature on major
physiological processes of plants

 There is a positive correlation between change in temperature and photosynthesis.
 When temperatures exceed from 15°C to 45°C, heat injury takes place and high
temperature hurts the enzymes responsible for photosynthesis.
 Photosynthesis decline, as temperature increases because photorespiration
increases with increase in temperature.
 Respiration rapidly increases with temperature and drops drastically after an
extreme tolerable temperature.
 The optimal temperature for structural integrity and activity of most enzymes are
within the range of 30-45°C; and enzymes are irreversibly denatured and
inactivated at temperatures higher than 50-60°C.
Explanation :
Schematic illustration of the effect of temperature on major
physiological processes of plants

Growth and developmental stages of rice
crop:

Growth and developmental stages of rice:
1) Germination 2) Seedling growth
3) Leaf emergence 4) Plant height
5) Tillering
1) Panicle initiation 2) Booting
3) Flag leaf emergence 4) Heading
5) Flowering / Anthesis
1) Maturity
2) Grain filling
3) Grain quality 4) Grain weight
Reproductive
stage
Vegetative
stage
Ripening
stage

Germination
Seedling
Tillering
Maximum
Tillering
Panicle
initiation
Flowering
Ripening
REPRODUCTIVE STAGE
VEGETATIVE STAGE RIPENING STAGE
Growth Stages of Rice:

1. Germination:
 Optimum temperature for
germination is 25-35oC
 Low temperature depresses the
rate of germination and prolongs
this stage for 5-6 days.
 High temperature of 35 ºC or
more halted the germination
because of high respiration rate.
2. Seedling Growth:
 Seedling growth rate increases
linearly between 22-31oC
 Chemical reactions, control growth
and above 40oC the plant may die.
3. Shoot and Root Elongation:
 Critical minimum temperature for
shoot and root elongation is 7-16 oC
and 12-16 oC respectively.
Effect of Temperature on Vegetative Stage:

4. Leaf Emergence:
 Temperature affects the rate of leaf
emergence.
Eg: When the temperature is 20oC,
leaves emerges 5-6 days before panicle
initiation.
When it is 25oC, they emerges 3-4 days
before panicle initiation (Bardhan and
Biswas., 1983).
5. Plant Height:
 It increased with increase in
temperature within the range of 30-
35oC.
 Plant elongates vigorously until 30
days after transplanting ,
then slowly cease to elongate at the
heading time.
Continued…

6. Tillering:
 Optimum temperature for
tillering is 25-31oC.
 Tillering rate is inhibited by
low temperature, due to which
the period of tillering is
prolonged.
Continued…

Tiller number, dry weight and relative growth rate of IR 8 at different
temperatures during the period from 3 to 5 weeks after sowing.

Effect of Temperature on Reproductive Stage:
1. Panicle Initiation:
 After active tillering stage ,high
temperatures decreases the number
of panicles , panicle weight especially
at maturity.
2. Booting and Heading:
 The optimum temperature for this
stage is 27-30oC
 When the rice plant is subjected to
low temperatures for 3 days , it is
more sensitive at booting stage than
heading, as indicated by the higher
percentage of spikelet sterility.

3. Flowering:
 The optimum temperature for flowering is 25-30oC.
 Yoshida(1981) observed that, 13 days delay in flowering for each
degree drop in temperature between 24oC and 21oC in IR26 rice cultivar.
 Both maximum and minimum temperature and lower diurnal variation in
temperature are more favorable for early flowering in rice varieties.
Continued…

Growth characteristics and number of spikelets of IR 8 grown at
different temperatures.

Ripening Stage
Grain Filling, Grain Quality, Grain Yield:
 Optimum temperature for ripening is 20-25 ºC.
 Low temperature reduces, grain dry matter increasing rate, extends the
grain filling and delays grain maturation.
 High temperature decreases grain yield significantly due to the
reduction in the percentage of ripened grains.

Effect of elevated temperature (2oC and 4oC) over ambient on
Accumulated Growing Degree Days (AGDD) during Kharif.

Spikelet degeneration (A) and incomplete panicle exsertion (B) of rice due to cold stress.
(A)
(B)
Mirza et al., 2013

 The critical temperature for inducing
spikelet sterility is from 10- 15 ºC.
 Cool weather causes panicle sterility
by interfering with pollen grain
formation.
 Observed that the temperature and
sterility had a negative correlation
which indicated that lower
temperature induced high sterility
(Yoshida,1981).
Low
Temperature
 Stated that the reduced yield was a
result of pollen shedding as well as
inadequate pollen growth in temperature
above 34ºC.
 High temperature leads to desiccation
of pollens.
 The high sterility is due to failure of
fertilization , caused by the imperfect
splitting of anther or wilting of stigma
induced by high temperature and low
humidity.
High
Temperature
Spikelet
Sterility
(Yoshida,1981).

Spikelet sterility (male sterility):
 t is an inability to release functional pollens
or anthers or male gametes.
Sterile spikelets due to cold stres
Mirza et al., 2013

Trait
Optimum
Temperature (⁰C)
References
Seed germination 25-35 Ueno and Miyoshi (2005)
Leaf emergence 25 Ellis et al. (1993)
Heading 27-30 Horie (1994)
Flowering 25-30 Nakagawa et al. (2005)
Seed-set 20-25 Ziska and Manalo (1996)
Optimum temperature for different growth and
developmental stages of rice
Mirza et al., 2013

Ranges of temperatures for seed germination of different
crops:
Crop species
Temperature (°C)
Minimum Maximum Optimum
Rice 10 45 20-35
Wheat 20 40 25-30
Maize 10 40 25-30
Soybean 10 35 25-30
Tomato 11 30 15-27
Cucumber 18 30 25-30
Water melon 15 35 25-30
Carrot 11 30 15-25
Mirza et al., 2013

Proteins produce due to temperature stress
High temperature stress proteins
1. Glutathione peroxidase
2. Chaperone protein ClpC3
3. Glutathione S-transferase
4. Dicer-like protein 4
5. Pyruvate decarboxylase 1
6. Actin-depolymerizing factor
7. Peptidyl-prolyl cis–trans isomerase
8. Heat shock 70 kDa protein
9. Proline etc.
Low temperature stress proteins
1. Sugar alcohol
a. Mannitol
b. Sorbitol
c. Pinitol and oligosaccharides such as
2. Trehalose
3. Zwitterionic compounds
4. Proline
5. Glycine-betaine etc.

 Plants produce various proteins to overcome biotic and
abiotic stresses.
 PSPDB is a web-accessible resource that covers 2,064
manually curated plant stress proteins from 134 plant
species.
 This database includes 30 different types of temperature
stress proteins in crops and higher plants.
Benefits:
 PSPDB is highly useful to the scientific community
involved in plant biotic and abiotic stress research
worldwide.
 This database is available at http://www.bioclues.org/pspdb
PSPDB: Plant Stress Protein Database
Anil Kumar et al. ( 2014).

Material and methods:
Rice genotypes
1. Nipponbare
2. M202
3. Cypress
4. Secano
Physiological responses to low-temperature stress in
rice genotypes at the reproductive stage:
Tolerant
Sensitive
 Seedlings transplanted into plastic pots
All genotypes were grown in the
greenhouse at 22-26°C ± 1°C.
 Light/dark cycle of 14/10 hour
 The pots placed in trays were full of
water flooded conditions.
The pots were divided into two
batches of 20 pots each, five per
genotype.
 A batch was kept under control
(28°C) with well irrigated water while
another set of trays were used for the
low temperature treatment at 10°C for
4 days.
Freitas et al., 2019
1

 Rice genotypes exposed to cold-stress
temperature at the reproductive stage
showed a significant reduction in
photosynthesis.
 In Secano do Brazil and Cypress
(cold-sensitive)
which showed a reduction of >70%
while Nipponbare and M202 showed
a reduction of ~35%.
Physiological parameters of rice genotypes in response to low temperature:
Continued…

 A similar pattern of reduction
among genotypes was also
observed for stomatal
conductance.
Continued…

 Water use efficiency (the ratio of
photosynthesis to transpiration)
showed a significant reduction in
Cypress and Secano do Brazil while
M202 and Nipponbare showed an
increase of 58% and 13.34%.
respectively.
Physiological parameters of rice genotypes in response to low temperature :
Continued…

the effect of low temperatures on
chlorophyll fluorescence (Fv’/Fm’)
was measured and verified that
Cypress and Secano do Brazil showed
a more significant reduction while
Nipponbare and M202 were reduced.
chlorophyll fluorescence
Continued…

 At reproductive stage under cold stress,
spikelet sterility was high showing 80%
and 90%, for the cold-sensitive Secano
do Brazil and Cypress, respectively.
 Nipponbare and M202 showing more
tolerance with a lower level of spikelet
sterility (38-42%).
Yield parameters evaluated for different rice genotypes treated to low
temperature
Continued…

 Cold stress severely affected the grain
yield as estimated by a number of
grains per panicle and 100 seed weight.
 Cypress and Secano do Brazil, showed
reduced yield than Nipponbare and
M202.
Yield parameters evaluated for different rice genotypes treated to low temperature
Continued…

Conclusion:
 Plants exposed to low temperatures
show increased membrane permeability,
inhibition of chlorophyll biosynthesis and
chloroplast damage.
 Photosynthesis is a early physiological
processes to be affected when plants are
subjected to unfavorable environmental
factors such as drought, high salinity and
low atmospheric temperatures etc.

Rice Improving Cold Stress Tolerance
Gothandam, 2012
Effect of Cold Stress on Rice:
 Rice crop is more sensitive to low temperature as its an tropical origin
 For rice cultivation temperatures lower than 20oC decrease
both the speed and the percentage of germination.
2

Effect of low temperature stress on rice seedlings and mature plant.
 Rice seedlings were exposed to 4 oC
for 12hr and then allowed to recover.
 Mature plants were exposed to 4 oC
for 36 hr and allowed to recover.
 Damage due to cold stress is seen as
wilting, chlorosis and necrosis in fig.
b & d.
Unstressed Cold stressed
(b)
(d)
(a)
(c)
Gothandam, 2012

Unstressed Cold stressed
 Cytological analysis of rice
anther development under cold
stress.
 Rice plants were exposed to
16 oC for 10 hours daylight.
 Cold stress resulted in
abnormal swelling of tapetum
layer and this abnormal
swelling leads to abortion of
microspores.
Gothandam, 2012

 Cold stress response is perceived by
plants through a signal transduction that
leads to the activation of transcription
factors and cold-responsive genes.
Effect of Cold stress on Plant Physiology:
Gothandam, 2012
Response

Production of Osmolytes increases cold stress tolerance:
 Wide range of compatible solutes are produced by
plants.
 Overproduction of various compatible solutes has
been tested in rice for example, glycine-betaine,
trehalose and proline to achieve significant cold
tolerance.
List of compatible solutes presenting cold tolerance in rice.
Gothandam, 2012

 Due to low temperature unpredictable cold snaps at
the reproductive stage delay heading and results in
pollen sterility.
 Pollen sterility is one of the key factor responsible
for the reduction in grain yield of rice.
Conclusion:
Gothandam, 2012

Temperature Effect on Yield and Yield Components of
Different Rice Cultivars in Flowering Stage
 This experiment include 5 varieties
1.Shirudi
2. Fajr
3. Local tarom
4. Line 843
5. Hybrid
 Two levels of temperatures
1. 𝑇1 (13 oC ) low temperature stress
2. 𝑇2 (32oC) control
Objective of the study,
 To evaluate the effect of cold stress on yield and yield components in flowering
stage.
Ghadirnezhad and Fallah, 2014
3

Effect of cultivars on yield and yield components across temperature.
Distinct letters in the row indicate significant differences among the varieties.
Continued…

Temperature effect on yield and yield components across varieties.
Distinct letters in the row indicate significant differences.
𝑇1 (13 oC ) low temperature stress
𝑇2 (32oC) control
Continued…

Interactive effects between cultivars and temperatures on yield and yield components.
Distinct letters in the row indicate significant differences.
V1: shirudi, V2: fajr, V3: local tarom, V4: line 843 and V5: hybrid cultivars.
𝑇1 (13 oC ) low temperature stress and 𝑇2 (32oC) control
46e
115.1a
Continued…

Conclusion:
 Low temperature (15-19oC) during the
reproductive stage damage microspore
development and causes the production of
sterile pollen grains, resulting in poor grain
filling and high spikelet sterility.

Physiological Basis of Screening Rice Varieties for
Low Temperature Stress Tolerance
Material and Methods:
 A field experiment was conducted at the Regional Research Station, Paiyur
 22 rice cultivars
Treated with low temperature stress
Objective: To screen different rice cultivars for low temperature stress
tolerance.
Kumar, A. A. and Surendar, K. K., 2019
4

Effect of low temperature stress on plant height, root length, number of tillers, number
of leaves and yield at 0 & 30 DAT.

Effect of low temperature stress on plant height, root length, number of tillers number
of leaves and yield at 60 & 90 DAT.

Effect of low temperature stress on growth attributes and yield of rice varieties

 Significant difference was observed for grain
yield among the varieties tested for low
temperature stress tolerance.
 Maximum grain yield was recorded in MDU3.
 Among the 22 varieties tested for low
temperature stress tolerance, MDU3 performed
better than other varieties.
Conclusion:
Kumar, A. A. and Surendar, K. K., 2019

1. Select low temperature tolerant cultivars/species
2. Chemical control ,
ABA, CCC and etc.
Other methods:
3. Proper planting dates
4. Artificial covers
5. Plant growth regulator as ABA
6. Adjust the cropping schedule to reduce the risk of unfavorable weather
condition during the reproductive and ripening stages.
7. Spikelet fertility is the most sensitive yield component when rice is
subjected to low or high temperature stress.
Methods to increase resistance to temperature
stress:

Conclusion:
 Exposure of rice plants to low temperature affects all phenological stages of
rice which results in lower grain production and reduced yield.
 In one of the case study as explained above, number of panicles, length of
panicle, number of full, empty, total grains, and yield had caused significant
reduction due to low temperature stress.
 Several methods have been proposed to reduce the threat of low temperature,
including substitution of cold-sensitive cultivars with cold tolerant cultivars,
setting of sowing time, and selection of varieties with a growth duration
permitting peak stress periods are some of the adaptive measures that will
help in the reduction of adverse effects of low temperature.

Freitas,G. P. M., Basu, S., Ramegowda, V., Thomas, J., Benitez, L. C. Braga, E. B.
and Pereira, A., 2019, Physiological responses to low-temperature stress in
rice genotypes at the reproductive stage. Plant Signaling & Behavior, 19
(5):53-64.
Ghadirnezhad, R. and Fallah, A., 2014, Temperature effect on yield and yield
components of different rice cultivars in flowering stage. Int. J. Agron.,
2014:1687-8159.
Kumar, A. A. and Surendar, K. K., 2019, Physiological Basis of screening rice
varieties for low temperature stress tolerance. Int. J. Curr. Microbiol. App. Sci.
8(10): 905- 910.
Journals referred:
1. International Journal of Current Microbiology and Applied Sciences (NASS
score: 5.38)
2. International Journal of Agronomy (NAAS score:9.38)
References:

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