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  • 1
    Electronic Resource
    Electronic Resource
    Response of in vitro pollen germination and pollen tube growth of groundnut (Arachis hypogaea L.) genotypes to temperature (2002)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 25 (2002), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Air temperatures of greater than 35 °C are frequently encountered in groundnut-growing regions, especially in the semi-arid tropics. Such extreme temperatures are likely to increase in frequency under future predicted climates. High air temperatures result in failure of peg and pod set due to lower pollen viability. The response of pollen germination and pollen tube growth to temperature was quantified in order to identify differences in pollen tolerance to temperature among 21 groundnut genotypes. Plants were grown from sowing to harvest in a poly-tunnel under an optimum temperature of 28/22 °C (day/night). Pollen was collected at anther dehiscence and was exposed to temperatures from 10° to 47·5 °C at 2·5 °C intervals. The results showed that a modified bilinear model most accurately described the response to temperature of percentage pollen germination and maximum pollen tube length. Genotypes were found to range from most tolerant to most susceptible based on both pollen characters and membrane thermostability. Mean cardinal temperatures (Tmin, Topt and Tmax) averaged over 21 genotypes were 14·1, 30·1 and 43·0 °C for percentage pollen germination and 14·6, 34·4 and 43·4 °C for maximum pollen tube length. The genotypes 55-437, ICG 1236, TMV 2 and ICGS 11 can be grouped as tolerant to high temperature and genotypes Kadiri 3, ICGV 92116 and ICGV 92118 as susceptible genotypes, based on the cardinal temperatures. The principal component analysis identified maximum percentage pollen germination and pollen tube length of the genotypes, and Tmax for the two processes as the most important pollen parameters in describing a genotypic tolerance to high temperature. The Tmin and Topt for pollen germination and tube growth, rate of pollen tube growth were less predictive in discriminating genotypes for high temperature tolerance. Genotypic differences in heat tolerance-based on pollen response were poorly related (R2 = 0·334, P = 0·006) to relative injury as determined by membrane thermostability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3040.2002.00943.x
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  • 2
    Electronic Resource
    Electronic Resource
    Adaptation of sorghum: characterisation of genotypic flowering responses to temperature and photoperiod (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 900-911 
    Details
    ISSN: 1432-2242
    Keywords: Key words Sorghum bicolor ; Flowering ; Temperature ; Photoperiod ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Sorghum [Sorghum bicolor (L.) Moench] is an important cereal crop grown in a wide range of tropical and temperate environments. This study was conducted to characterise the photothermal flowering responses of sorghum genotypes and to examine relationships between photothermal characteristics and environment of origin in order to better understand the phenological basis of adaptation to environment in sorghum. Twenty-four germplasm accessions and one hybrid from 24 major sorghum-growing areas were grown in a wide range of environments varying in temperature and photoperiod in India, Kenya and Mali between 1992 and 1995. Times from sowing to flowering (f) were recorded, and the responsiveness of 1/f to temperature and photoperiod was quantified using photothermal models. Times from sowing to flowering were accurately predicted in a wide range of environments using a multiplicative rate photothermal model. Significant variation in the minimum time to flower (Fm) and photoperiod sensitivity (critical photoperiod, Pc, and photoperiod-sensitivity slope, Ps) was observed among the genotypes; in contrast there was little variation in base temperature (Tb). Adaptation of sorghum to the diverse environments in which it is grown was largely determined by photoperiod sensitivity and minimum time to flower; photoperiod sensitivity determines broad adaptation to latitude (daylength), while variation in the minimum time to flower determines specific adaptation within smaller ranges of latitude, e.g. within the humid and sub-humid tropics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051311
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  • 3
    Electronic Resource
    Electronic Resource
    Sensitivity of Peanut to Timing of Heat Stress during Reproductive Development (1999)
    Springer
    Crop science 39 (1999), S. 1352-1357 
    Details
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Arachis hypogaea L.) crops grown in the semi-arid tropics are commonly exposed to damaging hot temperatures of above 40°C. The objectives of this research were to identify the time(s) during reproductive development when hot days reduce yield, and to examine relations between flower production and sensitivity to heat stress. At start of flower bud initiation (21 d after planting, DAP) plants of the cvs ICGV 86015 and ICGV 87282 were grown either at 28/22°C (optimum temperature, OT) or at 38/22°C (high temperature, HT) or were reciprocally transferred at 3-d intervals between the OT to Ht regimes and vice versa, until 46 DAP. Transferred plants remained in the new temperature regime for 6 d before being returned to their original regime. All plants were harvested at 67 DAP. In cv. ICGV 86015, transfers between 6 d before and 16 d after flowering (DAF) significantly (P 〈 0.001) affected total number of pegs (i.e., pegs and pods) and reproductive (peg and pod) dry weight, with the greatest effect occurring at 9 DAF. In cv. ICGV 87282, number of pegs and reproductive dry weights were also significantly reduced by transfers at 9 and 12 DAF. Heat stress had no effect on flower production or the proportion of pegs forming pods, but did significantly reduce the proportion of flower producing pegs. Data presented suggest that it is heat stress during floral bud development that determines peg number.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/
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  • 4
    Electronic Resource
    Electronic Resource
    A stability analysis of time to flowering as a screen for responsiveness to temperature and photoperiod in cowpea (Vigna unguiculata) (1996)
    Springer
    Euphytica 88 (1996), S. 77-84 
    Details
    ISSN: 1573-5060
    Keywords: cowpea ; flowering ; photoperiod ; stability analysis ; temperature ; Vigna unguiculata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Twenty-one genotypes of cowpea (Vigna unguiculata), comprising landraces and varieties, were grown in 22 photothermal environments in Nigeria and Niger, West Africa, and a stability analysis of days from sowing to flowering (f) was carried out. Cowpeas are rarely insensitive to photoperiod; they are typically quantitative shortday plants wherein f is delayed when photoperiod (P) is longer than the critical photoperiod (P c ). Therefore, in order to quantify genotypic variation in temperature sensitivity, genotype f was regressed against the mean trial f in circumstances where P〈P c (i.e. approximately ≤ 13 hd-1) and mean temperature (T) was between 19° and 28° C. Correspondingly, in order to assess genotypic variation in photoperiod sensitivity, trials where T was near optimal (25°–28° C) but where P ranged from 10–14.5 hd-1 were used. These stability analyses detected no significant differences (P〉0.05) between genotypes 9n temperature sensitivity but revealed significant differences (P〈0.001) in photoperiod sensitivity. Regression coefficients from the stability analysis were strongly correlated (r=0.94, 19df) with a photoperiod sensitivity constant, c′, determined from a photothermal flowering model. A stability analysis of f from field trials can therefore identify and quantify genotypic variation in response to temperature and photoperiod in cowpea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00029268
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  • 5
    Electronic Resource
    Electronic Resource
    Phenological adaptation to cropping environment. From evaluation descriptors of times to flowering to the genetic characterisation of flowering responses to photoperiod and temperature (1996)
    Springer
    Euphytica 92 (1996), S. 281-286 
    Details
    ISSN: 1573-5060
    Keywords: adaptation ; flowering ; photoperiod ; temperature ; germplasm ; characterisation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Descriptor lists for the major cereals and grain legumes include information on the duration from sowing to flowering. This is because the first step towards maximizing crop yield by agronomic management or plant breeding is to ensure that the phenology of the crop is well matched to the resources and constraints of the production environment. In this context, durations from sowing to flowering are of critical importance if crops sown on the appropriate date and at the appropriate density are to have the potential to yield well in a given environment. In most annual crops, the timing of phenological events is modulated primarily by responsiveness to photoperiod and temperature with large differences in sensitivity among genotypes. Irrespective of the crop, many advantages accrue from analyses of these photothermal responses not in terms of the evaluation descriptor ‘time from sowing to flowering (f)’ but in terms of the ‘rate of progress towards flowering (1/f)’. A computer program RoDMoD has been developed to convert evaluation descriptors for times of flowering to characterisation descriptors of the flowering response of a genotype to photoperiod and temperature. The program and the associated phenological model were developed from research undertaken in controlled environments and then validated in the field over wide ranges of locations and seasons. These advances should contribute to the development of cultivars phenologically well adapted to their target environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00022856
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