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درسی - 4-7

درسی

دوشنبه 19 اردیبهشت 1390

4-7

نویسنده: رضا کوشکی   

Fig. 2 Evolution of cardinal temperatures for wheat from vernalisation to grain filling (data source:
Porter and Gawith (1999)). VER vernalisation, SE sowing to emergence, TSI terminal spikelet
initiation, AT anthesis, GF grain filling

Downs (1972) found that grain yield and maximum dry matter production have a
Topt of 27/22◦ C. A recent study by Prasad et al. (2006) found that grain yield, harvest
index, pollen viability and percent seed-set have a Topt of 32/22◦ C and a Tfp of
40/30◦ C, and that vegetative biomass, photosynthesis and seed size has a Topt of
40/30◦ C, 44/34◦ C and 36/26◦ C respectively.
Summer cereal crops such as maize, rice and sorghum have relatively higher Topt
for crop growth and development compared with that of winter cereal crops such as
wheat. Reproductive stage of summer crops has relatively lower Topt compared with
vegetative stage.

 

2.2 Horticultural crops

Broccoli Tan et al. (1999) quantified and assessed the effects of a range of sub
zero Ts for a short period at different stages of crop development on the mortality,
yield and quality of broccoli. Whole plants in pots or in the field were subjected
to sub-zero T regimes from −1 to −19◦ C. It was found that lethal T for pot-grown
broccoli was between −5 ∼ −3◦ C, whereas the lethal T for field-grown broccoli was
between −9 ∼ −7◦ C. This study also found that the floral initiation is more sensitive
to freezing Ts than at florescence buttoning stage. Tan et al. (2000) estimated Tbase
and Topt for broccoli based on experimental studies in southeast Queensland. Three
cultivars (Fiesta, Greenbelt and Marathon) were sown on eight dates from 11 Mar.
to 22 May 1997 and grew under natural and extended (16 h) photoperiods under
non-limiting conditions of water and nutrient supply. This study found that broccoli
has a Tbase of 0◦ C and a Top of 20◦ C during the entire growing cycle. Unlike wheat,
cardinal Ts do not increase with the progression of broccoli life cycle.

Citrus Rosenzweig et al. (1996) summarized Topt ranges for different phenophases
of citrus. It was reported that dormancy stage has a Topt range of −4◦ C to 14◦ C. This
stage includes two sub-stages: hardening and pre-bloom. Their corresponding Topt
is −4◦ C to 8◦ C and 0◦ C to 14◦ C respectively. Flowering time has a Topt of 10–27◦ C.
Fruit set has a Topt of 22–27◦ C and fruit growth has a Topt of 20–33◦ C. Similar to
wheat crops Topt increases with the progression of citrus growth and development.

 

It was also reported that maturation has a Topt of 13–27◦ C for the development of
soluble sugars and 8–18◦ C for the development of colour. Maximum temperature of
35◦ C and minimum temperature of 2◦ C were identified as the temperature thresholds
for citrus across its growing season (Tahir Khurshid, pers. comm.).

It was also reported that maturation has a Topt of 13–27◦ C for the development of
soluble sugars and 8–18◦ C for the development of colour. Maximum temperature of
35◦ C and minimum temperature of 2◦ C were identified as the temperature thresholds
for citrus across its growing season (Tahir Khurshid, pers. comm.).

2.3 Legume crops

Dry bean/common bean Prasad et al. (2002) reported that dry bean seed yield has a
Topt of 23◦ C and a Tfp of 32◦ C. A study by Laing et al. (1984) stated that bean yield
has a Topt of 24◦ C.

 

 

The Tbase for peanut leaf appearance rate and onset of anthesis
is 10◦ C and 11◦ C respectively (Ong 1986). The Topt for leaf appearance rate is above
30◦ C while the Topt for rate of vegetative development to anthesis is between 29◦ C
and 33◦ C (Bolhuis and deGroot 1959). Leaf photosynthesis has a fairly high Topt of
36◦ C. Pollen viability and percent seed-set have a Topt of <31◦ C and a Tfp of 44/34◦ C
(Prasad et al. 2003). Percent fruit-set has a Topt of <33◦ C (bud temperature) and a
Tfp of 43◦ C (bud temperature) (Prasad et al. 2001). Cox (1979) observed that single
pod growth rate and pod size has a Topt of 24◦ C. Williams et al. (1975) found that
peanut yield has a Topt of 20◦ C. Hatfield et al. (2008) summarised that Topt for pod
yield, seed yield, pod harvest index and seed size is in the range of 23 ∼ 24◦ C and
with a Tfp of 40◦ C based on Prasad et al. (2003).

Soybean Reproductive development (time to anthesis) in soybean has a Tbase of
6◦ C and a Topt of 26◦ C (Boote et al. 1998). The post-anthesis phase has a lower Topt
of 23◦ C (Egli and Wardlaw 1980; Baker et al. 1989; Pan 1996; Thomas 2001; Boote
et al. 2005) compared with that of reproductive development. Pan (1996) and Thomas
(2001) found that mean temperature of 39◦ C is lethal to soybean yield production.
Averaged over many cultivars the cardinal temperatures (Tbase, Topt, and Tfp) were
13.2◦ C, 30.2◦ C and 47.2◦ C for pollen germination and 12.1◦ C, 36.1◦ C and 47.0◦ C for
pollen tube growth (Hatfield et al. 2008).

 

2.4 Other crops

It was reported that cotton vegetative development has a Tbase of 14◦ C and a Topt
of 37◦ C (Reddy et al. 1999 and 2005) which is higher than that of other crops due
to its higher adaptability to higher temperature environment (Hatfield et al. 2008).
However, cotton reproductive progression has a lower Topt of 28 ∼ 30◦ C (Reddy
et al. 1997 and 1999). Reddy et al. (2005) found that growth rate per boll has a Topt

 

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