growth stages, and plant type (Ruelland and Zachowski 2010). Some similar effects
of HS on morphology and physiology changes in wheat and maize are given below.
3.2.1 Morphological Responses
HS affects the whole plant from cellular to organ level. There is a general propensity
towards the reduction in cell size, curtailed water loss, and stomatal closure at the
cellular level. The impact of HS can be visualized from root to shoot and the
reproductive parts resulting in poor growth and productivity at the whole plant level.
3.2.1.1 Growth
The primary effect of HS impedes seedling establishment and poor germination in
the plant (Fahad et al. 2017). In T. aestivum HT ranging from 28
C to 30
C may
change the growth period by reducing seed germination and physiological maturity
(Yamamoto et al. 2008; Akter and Rafiqul Islam 2017) Temperature beyond (45
C)
in the early development stage (first 6 days of growth) in wheat attributed cell death
and embryo damage leads to germination failure (Essemine et al. 2010). Because,
HT retrograde mitochondria, alter the protein expression profiles, decreases ATP
(adenosine triphosphate) accumulation and oxygen uptake in imbibing embryos,
illation reduced germination percentage, plant emergence, abnormal seedlings, poor
seedling vigor, reduced radicle and plumule growth (Piramila et al. 2012), which
turn into degrading seed quality related to loss in mass, vigor, and germination in
wheat (Essemine et al. 2010; Balla et al. 2012; Hampton et al. 2013) and maize (Iloh
et al. 2014). In maize, there are dissident reports about post-emergence seedling
growth under HS. Momcilovic and Ristic (2007) study showed that the maize
coleoptile tolerant to HS at all stages of seedling development while Weaich et al.
(1996) and Akman (2009) reported that exposure to 40
C verily reduced coleoptile
growth and growth completely stopped at !45
C. Moreover, seedling grew under
HT (45–50
C) to promote leaf senescence and abscission (Kosova et al. 2011),
hindrance to gain height results in shorter and more bush-like morphology in maize
(Iloh et al. 2014; Laghri et al. 2012).
Day and night temperature (30/25
C) may have stiff effects on the development
of leaf viz., leaf area (Shah and Paulsen 2003), and leaf growth in wheat (Savicka
and Skute 2012). Wheat plant exposed to HS (>34
C) accentuated loss of chloroplast integrity, inhibits chlorophyll biosynthesis and denial of photosystem-IImediated electron transport (Haque et al. 2014) which is amenable to increase flag
leaf senescence in wheat (Ciuca and Petcu 2009; Asseng et al. 2013) and, also
attributed to a reduction in photosynthetic pigments therefore decline in photosynthetic activity in wheat (Balla et al. 2019). HT significantly declines relative growth
rate, shoot dry mass and internode length leads to stunted growth in maize (Weaich
et al. 1996; Ashraf and Hafeez 2004; Wahid et al. 2007). Ferris et al. (1998) studied
on spring wheat grew for 70 days at ambient temperature, rise in temperature for
12 days from 16
C to 25
C, resulted in a decrease in root mass without affecting
shoot mass but plants at 25
C found a well-developed root system in wheat (Huang
54
R. Gajghate et al.
of HS on morphology and physiology changes in wheat and maize are given below.
3.2.1 Morphological Responses
HS affects the whole plant from cellular to organ level. There is a general propensity
towards the reduction in cell size, curtailed water loss, and stomatal closure at the
cellular level. The impact of HS can be visualized from root to shoot and the
reproductive parts resulting in poor growth and productivity at the whole plant level.
3.2.1.1 Growth
The primary effect of HS impedes seedling establishment and poor germination in
the plant (Fahad et al. 2017). In T. aestivum HT ranging from 28
C to 30
C may
change the growth period by reducing seed germination and physiological maturity
(Yamamoto et al. 2008; Akter and Rafiqul Islam 2017) Temperature beyond (45
C)
in the early development stage (first 6 days of growth) in wheat attributed cell death
and embryo damage leads to germination failure (Essemine et al. 2010). Because,
HT retrograde mitochondria, alter the protein expression profiles, decreases ATP
(adenosine triphosphate) accumulation and oxygen uptake in imbibing embryos,
illation reduced germination percentage, plant emergence, abnormal seedlings, poor
seedling vigor, reduced radicle and plumule growth (Piramila et al. 2012), which
turn into degrading seed quality related to loss in mass, vigor, and germination in
wheat (Essemine et al. 2010; Balla et al. 2012; Hampton et al. 2013) and maize (Iloh
et al. 2014). In maize, there are dissident reports about post-emergence seedling
growth under HS. Momcilovic and Ristic (2007) study showed that the maize
coleoptile tolerant to HS at all stages of seedling development while Weaich et al.
(1996) and Akman (2009) reported that exposure to 40
C verily reduced coleoptile
growth and growth completely stopped at !45
C. Moreover, seedling grew under
HT (45–50
C) to promote leaf senescence and abscission (Kosova et al. 2011),
hindrance to gain height results in shorter and more bush-like morphology in maize
(Iloh et al. 2014; Laghri et al. 2012).
Day and night temperature (30/25
C) may have stiff effects on the development
of leaf viz., leaf area (Shah and Paulsen 2003), and leaf growth in wheat (Savicka
and Skute 2012). Wheat plant exposed to HS (>34
C) accentuated loss of chloroplast integrity, inhibits chlorophyll biosynthesis and denial of photosystem-IImediated electron transport (Haque et al. 2014) which is amenable to increase flag
leaf senescence in wheat (Ciuca and Petcu 2009; Asseng et al. 2013) and, also
attributed to a reduction in photosynthetic pigments therefore decline in photosynthetic activity in wheat (Balla et al. 2019). HT significantly declines relative growth
rate, shoot dry mass and internode length leads to stunted growth in maize (Weaich
et al. 1996; Ashraf and Hafeez 2004; Wahid et al. 2007). Ferris et al. (1998) studied
on spring wheat grew for 70 days at ambient temperature, rise in temperature for
12 days from 16
C to 25
C, resulted in a decrease in root mass without affecting
shoot mass but plants at 25
C found a well-developed root system in wheat (Huang
54
R. Gajghate et al.