EFFECTS OF 10- AND 20-HOUR PHOTOPERIOD TREATMENTS AT 20 AND 30 C ON RATE OF DEVELOPMENT OF A SINGLE-CROSS MAIZE (ZEA MAYS) HYBRID

1976 ◽  
Vol 56 (4) ◽  
pp. 795-798 ◽  
Author(s):  
C. M. BREUER ◽  
R. B. HUNTER ◽  
L. W. KANNENBERG
Keyword(s):  
Zea Mays ◽  
Low Temperature ◽  
Grain Filling ◽  
Temperature Treatment ◽  
Rate Of Development ◽  
Low Temperature Treatment ◽  
Single Cross ◽  
Grain Filling Period ◽  
Temperature Interaction ◽  
Time Required

A single-cross maize (Zea mays L.) hybrid was grown under two photoperiods (10 and 20 h) at two constant temperatures (20 and 30 C). Rate of development was characterized by the number of days from planting to tassel initiation, tassel initiation to silking, and silking to maturity. Long photoperiod and low temperature independently increased the number of days between planting and tassel initiation. The interval between tassel initiation and silking was not affected by photoperiod, but was increased significantly by the low temperature treatment. During the grain filling period (silking to maturity), temperature had the principal effect, but a photoperiod by temperature interaction did occur. Although plants grown at 20 C required more days to reach maturity than those grown at 30 C, the filling period at 20 C was shorter under the 10-h photoperiod than under the 20-h photoperiod, but at 30 C, the 10-h photoperiod treatment had the longer filling period. The delay in development at the low temperature, although apparent at all three stages of development, was not of the same magnitude. When the delay in development at 20 C is expressed as a percent of time required at 30 C, the 20 C treatment took 28% longer between planting and tassel initiation than the 30 C treatment. The corresponding figures for days between tassel initiation and silking and between silking and maturity were 58 and 46%, respectively.

EFFECTS OF PHOTOPERIOD AND TEMPERATURE ON VEGETATIVE AND REPRODUCTIVE GROWTH OF A MAIZE (ZEA MAYS) HYBRID

1977 ◽  
Vol 57 (4) ◽  
pp. 1127-1133 ◽  
Author(s):  
R. B. HUNTER ◽  
M. TOLLENAAR ◽  
C. M. BREUER
Keyword(s):  
Zea Mays ◽  
Grain Yield ◽  
Dry Weight ◽  
Grain Filling ◽  
Temperature Treatment ◽  
Limiting Factor ◽  
Grain Filling Period ◽  
Temperature Interaction ◽  
Lower Temperature ◽  
Vegetative And Reproductive Growth

A single-cross maize (Zea mays L.) hybrid was grown to maturity in the four combinations of two temperatures, 20 and 30 C, and two photoperiods, 10 and 20 h, in controlled-environment growth cabinets. Measurements of dry weights of plant components were made at tassel initiation, mid-anthesis, mid-anthesis plus 16 days, and maturity. The longer photoperiod and cooler temperature treatment produced the highest final plant dry weight. Average daily dry matter (DM) production was greater for plants grown at the longer photoperiod. This could largely be attributed to a higher leaf area per plant. The duration of DM production was longer at the cooler temperature. Grain yields were higher under the lower temperature because of an increase in the length of the grain-filling period and because a greater proportion of the post-anthesis DM was allocated to the grain. The results of this study showed a significant photoperiod × temperature interaction for length of the grain-filling period, kernel number and grain yield. Post-anthesis DM accumulation did not appear to be a limiting factor for grain yield. The effects of temperature and photoperiod on length of the grain-filling period and grain yield may have been partly mediated through the size of the grain sink.

scholarly journals Dynamics of starch synthesis enzymes and their relationship with chalkiness of early indica rice under different postanthesis temperature regimes

2019 ◽  
Vol 44 (2) ◽  
pp. 223-238
Author(s):  
Mohammed Humayun Kabir ◽  
Qing Liu ◽  
Shitou Xia ◽  
Ruozhong Wang ◽  
Langtao Xiao
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Indica Rice ◽  
Starch Synthesis ◽  
Grain Filling ◽  
Temperature Treatment ◽  
Low Temperature Treatment ◽  
Temperature Regimes ◽  
Grain Filling Rate ◽  
Head Rice

An experiment on an early indica rice cv. ‘Shenyou9576’ was conducted in the Key Laboratory of Phytohormones and Growth Development of Hunan Agricultural University, Changsha, Hunan, PR China in 2014 to investigate the influence of varying post-anthesis temperatures on chalkiness rate, head rice rate, and on major 6 starch synthesis enzymes i.e., SuSy (EC 1.9.3.1), ADPG-Ppas (EC 2.7.7.27), SSS (EC 2.4.1.21) and GBSS, (EC 2.4.1.21), SBE (EC 2.4.1.18) and SDBE (EC 3.2.1.70). The treatments comprised of three temperature regimes which are designated as the high (35/28oC- day/night), low (25/20oC- day/night) and natural condition (35/25oC-day/night) as the control. Under high temperature maximum chalkiness rate was 61.11% and minimum was 22.59% under low temperature treatment. The lowest head rice rate was 42.76% under high temperature treatment followed by 49.91% in the control, while the highest rate was 62.33% under low temperature treatment. Maximum grain filling rate (Gmax) was found highest (1.69 mg/day) in the high temperature and average grain filling rate (Gavg) was found highest (1.36 mg/day) under the control. The activity of SuSy, ADPG-Ppase, SSS and GBSS were decreased gradually from 14 to 35 days after flowering (DAF). Irrespective of the treatments, an increasing trend of ADPG-Ppase activity was observed from 7 to 14 DAF and then declined. Correlation between the chalkiness and the enzymes activity of SuSy, ADPG-Ppase and SSS were significantly negative at 21, 28 and 35 DAFs, i.e., higher activity of SuSy, ADPG-Ppase and SSS at the mid-late to the late caryopsis development stage mediated by low temperature treatment played an important role for the reduction of chalkiness. The correlation between GBSS activity and chalkiness was significantly negative and stronger at 14, 21 and 28 DAF indicating that GBSS played a cardinal role to reduce chalkiness in the mid to mid-late stage of rice grain development. Significantly negative correlation was found between starch branching enzyme (SBE) and chalkiness at 21, 28 and 35 DAF, i.e., the higher SBE activity under low temperature treatment at the later grain filling stage also had a positive role in reduction of chalkiness. Bangladesh J. Agril. Res. 44(2): 223-238, June 2019

Effects of short-term temperature fluctuations on leaf photosynthesis in corn (Zea mays)

1979 ◽  
Vol 57 (21) ◽  
pp. 2387-2393 ◽  
Author(s):  
M. R. Thiagarajah ◽  
L. A. Hunt ◽  
R. B. Hunter
Keyword(s):  
Zea Mays ◽  
Low Temperature ◽  
Temperature Stability ◽  
Temperature Fluctuations ◽  
Complete Recovery ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Genotypic Differences ◽  
Short Term ◽  
Low Temperature Treatment

The effects of short-term temperature fluctuations on net photosynthetic rates (Pn) are described for a single-cross corn (Zea mays L.) hybrid (Harrow 691). The hybrid was grown at 25 °C and subjected to 4 days at either 15 or35 °C, and then maintained at 25 °C. Genotypic differences in tolerance of Pn to low temperature were studied using 12 hybrids of different maturities grown at 25 °C and subjected to 4 days at 15 °C.Following low temperature treatment. Pn was initially reduced by about 15% for leaves 5. 9. and 13 of hybrid Harrow 691. but completely recovered after 1 day at 25 °C. Following high temperature treatment, leaves 5 and 9 showed similar reductions in Pn whereas leaf 13 was not affected. The photosynthetic activity of the heat-stressed leaf 9 recovered after 1 day, but that of leaf 5 showed no recovery for 14 days at 25 °C.Among 12 hybrids. Pn of the newly matured leaf 7 was reduced after the low temperature treatment, but the reduction was more drastic for two late hybrids than for three early hybrids. Most hybrids showed complete recovery of Pn after 1 day at 25 °C. but genotypic differences were evident. The results reported indicate that further evaluation of the amount of genetic variation in temperature stability in corn could be carried out usefully.

Studies on Freshwater Osmoregulation in the Ammocoete larva of Lampetra Planeri (Bloch)

1968 ◽  
Vol 48 (3) ◽  
pp. 597-609
Author(s):  
R. MORRIS ◽  
J. M. BULL
Keyword(s):  
Low Temperature ◽  
Extracellular Space ◽  
Ringer Solution ◽  
Temperature Treatment ◽  
Sodium Influx ◽  
Sodium Chloride Solutions ◽  
Low Temperature Treatment ◽  
Lampetra Planeri ◽  
Equilibrium Concentrations ◽  
Sodium Loss

1. An investigation has been made of the factors which cause sodium loss from ammocoetes when they are immersed in de-ionized water at 1° and 10° C. 2. Sodium influx ceases when animals are first immersed in de-ionized water, but can recommence when the animal loses sufficient sodium to the environment. The concentration of sodium required for influx to take place decreases with succeeding periods of immersion in de-ionized water at 10° C. and reaches minimum equilibrium concentrations as low as 0.005 mM-Na/l. 3. Low temperature inhibits sodium influx and thus promotes net loss of sodium to de-ionized water. 4. Low temperature also decreases the initial loss of sodium to de-ionized water and probably lowers the permeability of the external surfaces of the animal to ions. This effect is small compared with the inhibition of ion uptake so that the combined result is to increase the net loss of sodium from the animal. 5. Since animals lose calcium to de-ionized water and show a decreased rate of sodium loss when calcium salts are added, it is believed that the high rates of sodium loss in de-ionized water are attributable to the effect of calcium on permeability. 6. Lack of calcium may also explain why animals which have been depleted of sodium by low-temperature treatment take up sodium much faster at higher temperatures from dilute Ringer solutions than from pure sodium chloride solutions. 7. When animals lose ions to de-ionized water at low temperature, sodium and chloride are lost from the extracellular space, whilst the muscle cells lose potassium. These ions are recovered into the extracellular space when animals are allowed to take up ions at 10° C. from diluted Ringer solution later.

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