Peter Kettlewell | Harper Adams University (original) (raw)
Papers by Peter Kettlewell
Outlook on Agriculture, 2014
ABSTRACT Long-distance signals moving from roots to shoots in response to drought lead to reduced... more ABSTRACT Long-distance signals moving from roots to shoots in response to drought lead to reduced vegetative growth. The hypothesis that the artificial manipulation of one of these signals, alkalization of the xylem sap, can reduce problems of excessive growth in arable crops, has been tested in oilseed rape (canola; Brassica napus L.) and barley (Hordeum vulgare L.). Experiments with detached shoots have shown that both crop species can respond to artificial alkaline xylem sap with reduced leaf expansion. Applications of alkalizing agents to intact plants, either as pH buffer sprays or as solid calcium carbonate, have successfully retarded leaf expansion. The retardation has, however, either been inconsistent (possibly through difficulty in penetrating the variable epicuticular wax layer) or of very short duration (possibly through efficient buffering of internal pH). It can be inferred from these results that the greatest commercial potential for alkalizing growth retardants may be with high-value, short-duration crops that do not have a thick layer of epicuticular wax, and using either multiple applications or persistent formulations.
The purpose of this paper is to quantify the economic impact of variation in alcohol yield from w... more The purpose of this paper is to quantify the economic impact of variation in alcohol yield from wheat grain used as the feedstock in the emerging UK bioethanol industry. Analysis of alcohol yield of 84 Recommended List samples shows that the annual cost saving from high alcohol yield wheat compared with low alcohol yield wheat could exceed ?3 million per annum or ?34 per tonne of wheat processed in a plant with a capacity of 100k tonnes of wheat per year.
Journal of Cereal Science, 2015
The occurrence of pre-maturity a-amylase (PMA) is a major cause of poor bread-making quality (low... more The occurrence of pre-maturity a-amylase (PMA) is a major cause of poor bread-making quality (low Hagberg Falling Number) in wheat grain. In susceptible genotypes, it involves the excessive accumulation of high isoelectric point (pI) a-amylase in mature grain prior to germination and in the absence of preharvest sprouting. Several factors regulate PMA formation in developing grain, including genotype, agronomy, and environmental conditions. In particular, a cold period during mid-grain development has been found to be a major stimulus for PMA induction. Although the factors affecting the PMA occurrence are well known, little is known about the molecular mechanism governing its induction. The plant hormones abscisic acid (ABA) and gibberellins (GAs) influence various aspects of grain development, and it has been suggested that PMA involves changes in the amount of these hormones or the sensitivity of the grain to these hormones. This review summarizes recent studies investigating the role of ABA and GAs in PMA induction and PMA occurrence.
Communications in agricultural and applied biological sciences, 2009
The overaLl aim of the study described in this communication was to utilise the findings of a glo... more The overaLl aim of the study described in this communication was to utilise the findings of a global scientific and technical literature survey on the use of inorganic salts against crop fungal diseases in order to assess the potential of using these substances to reduce the reliance of UK growers on conventional fungicides. A summary of the main findings of the Literature survey is provided followed by information on the current commercial use of inorganic salt-based products in fungal disease management. Finally, the scope of potential use of inorganic salts on high disease risk crops in the UK is assessed and specific crop/pathogen combinations are prioritised for further research.
Communications in agricultural and applied biological sciences, 2008
The present review provides an update of recent progress in the use of inorganic salts to manage ... more The present review provides an update of recent progress in the use of inorganic salts to manage powdery mildew (Sphaerotheca fuliginea and Erysiphe cichoracearum) in cucurbits (Cucurbitaceae). A literature survey identified 16 salts, mainly bicarbonates (e.g. KHCO3), phosphates (e.g. K2HPO4) and silicates (e.g. Na2SiO3), as having potential to suppress powdery mildew in cucurbits. The percentage suppression compared with untreated controls was calculated from the best treatment of each of 20 peer-reviewed studies and this ranged from 41-99%. The high efficacy of inorganic salts in suppressing cucurbit powdery mildew coupled with the abundance of formulated inorganic salt-based products may enable a reduction in the number of conventional fungicide applications needed to control the disease. Overall, the survey revealed that spray or hydroponic applications of inorganic salts can be a useful component in the integrated management of cucurbit powdery mildew, leading to potential envi...
Annals of botany, 2008
The premature production of alpha-amylase without visible germination has been observed in develo... more The premature production of alpha-amylase without visible germination has been observed in developing grain of many cereals. The phenomenon is associated with cool temperatures in the late stages of grain growth but the mechanisms behind it are largely unknown. The aim of this study was to replicate the phenomenon under controlled conditions and investigate the possibility of a mechanistic link with grain size or endosperm cavity size. Five wheat (Triticum aestivum) genotypes differing in their susceptibility to premature alpha-amylase were subjected to a range of temperature shocks in controlled environments. A comparison was then made with plants grown under ambient conditions but with grain size altered by using degraining to increase the assimilate supply. At maturity, alpha-amylase, grain area and endosperm cavity area were measured in individual grains. Both cold and heat shocks were successful in inducing premature alpha-amylase in susceptible genotypes, with cold shocks the ...
Scientific Reports, 2014
To study the role of abscisic acid (ABA) and gibberellins (GA) in pre-maturity a-amylase (PMA) fo... more To study the role of abscisic acid (ABA) and gibberellins (GA) in pre-maturity a-amylase (PMA) formation in developing wheat grain, two glasshouse experiments were conducted under controlled conditions in the highly PMA-susceptible genotype Rialto. The first, determined the relative efficacy of applying hormone solutions by injection into the peduncle compared to direct application to the intact grain. The second, examined the effects of each hormone, applied by either method, at mid-grain development on PMA in mature grains. In the first experiment, tritiated ABA ( 3 H-ABA) and gibberellic acid ( 3 H-GA 3 ) were diluted with unlabelled ABA (100 mM) and GA 3 (50 mM), respectively, and applied at mid-grain development using both methods. Spikes were harvested after 24, 48 and 72 h from application, and hormone taken up by grains was determined. After 72 h, the uptake per grain in terms of hormones applied was approximately 13% for ABA and 8% for GA 3 when applied onto the grains, and approximately 17% for ABA and 5% for GA 3 when applied by injection. In the second experiment, applied ABA reduced, whereas applied GA 3 increased a-amylase activity. This confirmed that exogenously applied ABA and GA were absorbed in sufficient amounts to alter grain metabolism and impact on PMA. E xogenous hormone application is an important experimental technique for helping to understand the hormonal control of plant growth and development. Different methods have been used to study the effects of exogenous hormones on grain development. A few studies have dealt with pre-anthesis hormone regulation of floret development 31 , whereas most studies investigated grain development after anthesis 22 . Generally in cereals, abscisic acid (ABA) and gibberellic acid (GA 3 ) solutions have been applied separately either by spraying onto the leaves and spikes 1,7,31-32 or by injecting into the leaf sheath 31 to study their role in floret development, grain set and filling. Yang et al. 32 applied ABA (20 mM) by spraying the leaves and panicles in two rice cultivars, Wuyujing 3 and Yangdao 4, daily for 7 days starting at 9 days after anthesis (DAA), and observed a 3-to 4-fold increase in ABA levels in grains at 12 and 20 DAA in ABA-treated plants compared to plants treated with water in both cultivars. Similar results were reported later by , after spraying ABA (20 mM) solution onto the panicles of rice plants daily for 8 days starting at the initiation of heading, and ABA levels in grains were measured at 9 and 16 DAA. They observed that an increase in the endogenous ABA levels in grains was about 4-fold at 9 DAA and 2-fold at 16 DAA in ABA-treated plants compared to plants treated with water. In both studies, ABA was quantified by the enzyme-linked immunosorbent assay (ELISA) using mouse monoclonal antibodies against ABA. This shows that a substantial amount of applied ABA reaches the grain in a biological active form. The role of ABA and gibberellins (GA) in regulating a-amylase formation in germinating and pre-harvest sprouted wheat grains is well documented in the literature . However, their role in regulating pre-maturity a-amylase (PMA) synthesis in intact, developing wheat grains is less well known. In order to determine the role of ABA and GA in a-amylase formation in developing grains, it is necessary to investigate the most effective method for in situ hormone application to ensure that the applied hormones are being taken up by the grains.
Euphytica, 2002
Dormancy of wheat grains, the property conferring sprouting resistance, is affected by environmen... more Dormancy of wheat grains, the property conferring sprouting resistance, is affected by environmental conditions experienced during grain development. We investigated the hypothesis that short dormancy duration in U.K. wheat grain (thus a high risk of post-maturity sprouting) is related to weather conditions, i.e. high temperatures during grain development. Four wheat varieties were grown at four sites ranging from the far
The Journal of Agricultural Science, 2008
Previous work has shown that the national average quality of the UK wheat crop from 1974 to 1999 ... more Previous work has shown that the national average quality of the UK wheat crop from 1974 to 1999 was associated with the preceding winter North Atlantic Oscillation (NAO). The association of the winter NAO with the grain quality measure, specific weight, was shown to be mediated by sunshine duration during grain filling and unconditional wet day probability during grain ripening (the probability of a wet day following either a dry or a wet day). The present study tests the hypothesis that the association between specific weight and the winter NAO can be detected in data from 158 years of the Broadbalk Wheat Experiment at Rothamsted in south-east England. Specific weight from the Broadbalk Experiment responded to sunshine duration during grain filling and unconditional wet day probability during grain ripening in a similar way to the national average data. An association with the winter NAO was found in the Broadbalk data from 1956 to 2001, but not in the previous 112 years . This finding is consistent with other work showing significant correlations between the winter NAO and summer climate only in recent decades. It is concluded that the association between wheat quality and the NAO is a recent phenomenon.
The Journal of Agricultural Science, 2012
ABSTRACT Four field experiments were conducted on wheat, using the bread-making cultivar Hereward... more ABSTRACT Four field experiments were conducted on wheat, using the bread-making cultivar Hereward, over 3 years to study the interactions between nitrogen (N) and strobilurin fungicides with respect to yield and grain N. In one of the field experiments, above-ground dry matter (DM) yield was greater when the plots were treated with a mixture of triazole and strobilurin than when either no fungicide or triazole alone was applied. On plots that received no N fertilizer, above-ground DM and grain yield were lower for the plots treated with fungicides than for plots not treated with fungicide, which implied that the benefit of applying fungicides could only be exploited with N fertilization. There was no difference in above-ground N accumulation between fungicide programmes; however, greater N accumulation in grains was observed following the application of a mixture of triazole and the strobilurin trifloxystrobin compared with plots treated with either no fungicide or triazole alone. This increase in grain N appeared to be attributable more to improved translocation of N to grains rather than to increased N uptake from the soil. The two strobilurin fungicide ingredients kresoxim-methyl and trifloxystrobin, each mixed with a triazole and tested in the present study, performed differently. Better performance, especially with respect to grain N yield, was observed most frequently with trifloxystrobin compared to kresoxim-methyl.
The Journal of Agricultural Science, 1983
... BY PS KETTLEWELL, ELERI A. WHITLEY*, WS MEREDITHf Harper Adams Agricultural College, Newport,... more ... BY PS KETTLEWELL, ELERI A. WHITLEY*, WS MEREDITHf Harper Adams Agricultural College, Newport, Shropshire, TF10 8NB AND R. SYLVESTER-BRADLEY Plant Physiology Unit, Ministry of Agriculture, Fisheries and Food, Woodthorne, Wolverhampton, WVQ 8TQ ...
The Journal of Agricultural Science, 1997
ABSTRACT The hypothesis was tested that slow grain drying stimulates pre-maturity alpha-amylase a... more ABSTRACT The hypothesis was tested that slow grain drying stimulates pre-maturity alpha-amylase activity in wheat (Triticum aestivum L.). Grain drying rate in 91 commercial crops of cultivars Avalon or Mercia grown over the years 1988–90 was estimated from the slope of linear regressions of moisture content on time. Incipient sprouting was detected in some samples from 1988 using the fluoroscein dibutyrate test, but results from a beta-limit dextrin gel assay indicated that pre-maturity alpha-amylase was probably the major source of alpha-amylase activity in these samples. Although year-to-year differences in ln alpha-amylase activity and Hagberg falling number tended to be associated with seasonal differences in drying rate, there was no evidence of a relationship between either ln alpha-amylase activity or Hagberg falling number and drying rate after the year effect was removed by an analysis of covariance. A second dataset from one crop in each of 14 years at one site showed significant positive linear relationships between cumulative potential evapotranspiration calculated over different periods during grain ripening and Hagberg falling number (excluding 3 years when incipient sprouting was thought to occur). It was concluded that pre-maturity alpha-amylase activity was stimulated by an unknown environmental factor differing between seasons and associated with seasonal differences in drying rate and cumulative potential evapotranspiration.
The Journal of Agricultural Science, 1997
... Draper 1982). This, therefore, can explain the negative relationship between HFN and August r... more ... Draper 1982). This, therefore, can explain the negative relationship between HFN and August rainfall. Delayed drying of the grain may also reduce HFN in the absence of sprouting (Gale et al. 1983; Gooding et al. 1994), which ...
The Journal of Agricultural Science, 2006
The Journal of Agricultural Science, 1986
ABSTRACT
The Journal of Agricultural Science, 2002
ABSTRACT Supplying a proportion of the N requirement of a wheat crop via the foliage would potent... more ABSTRACT Supplying a proportion of the N requirement of a wheat crop via the foliage would potentially reduce immobilization of fertilizer N in the soil organic matter and N losses by leaching or denitrification. A field experiment was carried out at Harper Adams in Shropshire to investigate the effect on crop yield of supplying the spring N application to winter wheat as different proportions of urea as a solution rather than as conventional soil-applied urea, and to determine the physiological basis of any yield differences. A solid ammonium nitrate treatment was included to represent alternative commercial practice to solid urea. Treatments were repeated on the same plots over the 3 years 1992, 1993 and 1994. Solid fertilizer was applied as a single dressing, whereas urea sprays were split over a number of days to reduce scorch. Nitrogen as urea sprays produced similar grain yields to N applied conventionally to the soil as solid ammonium nitrate or urea, but effects on above-ground dry matter production and harvest index depended on the time of application. Application of a large proportion of N as urea sprays, such that some of the N as urea solution was applied later in relation to crop development, produced less above-ground dry matter, but compensated by increasing harvest index. It is concluded that application of N as urea sprays could be successfully used to substitute for soil-applied N fertilizer at stem extension in winter wheat without loss of yield. Extra application costs, however, are likely to outweigh any efficiency or environmental benefits, except where applications of solid N are made to dry soils.
The Journal of Agricultural Science, 1991
... to obtain maximum yield (Sylvester-Bradley et al. 1984). The yield increase by urea in Shrops... more ... to obtain maximum yield (Sylvester-Bradley et al. 1984). The yield increase by urea in Shropshire 1985, however, contrasts with this trend because an adjacent ex-periment showed that the application of nitrogen fertilizer in the spring was optimal for yield (Gooding 1988). ...
The Journal of Agricultural Science, 1995
ABSTRACT Elemental sulphur (32 kg S/ha) and urea (30 kg N/ha) were applied to the foliage of diff... more ABSTRACT Elemental sulphur (32 kg S/ha) and urea (30 kg N/ha) were applied to the foliage of different winter wheat cultivars, halfat flag leaf emergence and halfat ear emergence, in factorial experiments in 1986, 1987 and 1988. There were no clear visual symptoms of S deficiency, but there was evidence from soil analysis, grain S concentration and grain N:S ratio that the crops were marginally deficient in sulphur. Disease severity was generally negligible. Leaf senescence at the end of grain growth was delayed by sulphur in two of the three years, both with and without urea in 1987, but only with urea in 1988. Sulphur, both alone and mixed with urea, increased grain S concentration from early grain growth in 1986 and 1987, but not until the end of grain growth in 1988. Urea alone reduced yield in 1986 and 1987, but mixing S with the urea compensated for this phytotoxic effect. Yield was not significantly increased by S when compared with plots receiving neither urea nor S.
The Journal of Agricultural Science, 1982
The Journal of Agricultural Science, 2007
Outlook on Agriculture, 2014
ABSTRACT Long-distance signals moving from roots to shoots in response to drought lead to reduced... more ABSTRACT Long-distance signals moving from roots to shoots in response to drought lead to reduced vegetative growth. The hypothesis that the artificial manipulation of one of these signals, alkalization of the xylem sap, can reduce problems of excessive growth in arable crops, has been tested in oilseed rape (canola; Brassica napus L.) and barley (Hordeum vulgare L.). Experiments with detached shoots have shown that both crop species can respond to artificial alkaline xylem sap with reduced leaf expansion. Applications of alkalizing agents to intact plants, either as pH buffer sprays or as solid calcium carbonate, have successfully retarded leaf expansion. The retardation has, however, either been inconsistent (possibly through difficulty in penetrating the variable epicuticular wax layer) or of very short duration (possibly through efficient buffering of internal pH). It can be inferred from these results that the greatest commercial potential for alkalizing growth retardants may be with high-value, short-duration crops that do not have a thick layer of epicuticular wax, and using either multiple applications or persistent formulations.
The purpose of this paper is to quantify the economic impact of variation in alcohol yield from w... more The purpose of this paper is to quantify the economic impact of variation in alcohol yield from wheat grain used as the feedstock in the emerging UK bioethanol industry. Analysis of alcohol yield of 84 Recommended List samples shows that the annual cost saving from high alcohol yield wheat compared with low alcohol yield wheat could exceed ?3 million per annum or ?34 per tonne of wheat processed in a plant with a capacity of 100k tonnes of wheat per year.
Journal of Cereal Science, 2015
The occurrence of pre-maturity a-amylase (PMA) is a major cause of poor bread-making quality (low... more The occurrence of pre-maturity a-amylase (PMA) is a major cause of poor bread-making quality (low Hagberg Falling Number) in wheat grain. In susceptible genotypes, it involves the excessive accumulation of high isoelectric point (pI) a-amylase in mature grain prior to germination and in the absence of preharvest sprouting. Several factors regulate PMA formation in developing grain, including genotype, agronomy, and environmental conditions. In particular, a cold period during mid-grain development has been found to be a major stimulus for PMA induction. Although the factors affecting the PMA occurrence are well known, little is known about the molecular mechanism governing its induction. The plant hormones abscisic acid (ABA) and gibberellins (GAs) influence various aspects of grain development, and it has been suggested that PMA involves changes in the amount of these hormones or the sensitivity of the grain to these hormones. This review summarizes recent studies investigating the role of ABA and GAs in PMA induction and PMA occurrence.
Communications in agricultural and applied biological sciences, 2009
The overaLl aim of the study described in this communication was to utilise the findings of a glo... more The overaLl aim of the study described in this communication was to utilise the findings of a global scientific and technical literature survey on the use of inorganic salts against crop fungal diseases in order to assess the potential of using these substances to reduce the reliance of UK growers on conventional fungicides. A summary of the main findings of the Literature survey is provided followed by information on the current commercial use of inorganic salt-based products in fungal disease management. Finally, the scope of potential use of inorganic salts on high disease risk crops in the UK is assessed and specific crop/pathogen combinations are prioritised for further research.
Communications in agricultural and applied biological sciences, 2008
The present review provides an update of recent progress in the use of inorganic salts to manage ... more The present review provides an update of recent progress in the use of inorganic salts to manage powdery mildew (Sphaerotheca fuliginea and Erysiphe cichoracearum) in cucurbits (Cucurbitaceae). A literature survey identified 16 salts, mainly bicarbonates (e.g. KHCO3), phosphates (e.g. K2HPO4) and silicates (e.g. Na2SiO3), as having potential to suppress powdery mildew in cucurbits. The percentage suppression compared with untreated controls was calculated from the best treatment of each of 20 peer-reviewed studies and this ranged from 41-99%. The high efficacy of inorganic salts in suppressing cucurbit powdery mildew coupled with the abundance of formulated inorganic salt-based products may enable a reduction in the number of conventional fungicide applications needed to control the disease. Overall, the survey revealed that spray or hydroponic applications of inorganic salts can be a useful component in the integrated management of cucurbit powdery mildew, leading to potential envi...
Annals of botany, 2008
The premature production of alpha-amylase without visible germination has been observed in develo... more The premature production of alpha-amylase without visible germination has been observed in developing grain of many cereals. The phenomenon is associated with cool temperatures in the late stages of grain growth but the mechanisms behind it are largely unknown. The aim of this study was to replicate the phenomenon under controlled conditions and investigate the possibility of a mechanistic link with grain size or endosperm cavity size. Five wheat (Triticum aestivum) genotypes differing in their susceptibility to premature alpha-amylase were subjected to a range of temperature shocks in controlled environments. A comparison was then made with plants grown under ambient conditions but with grain size altered by using degraining to increase the assimilate supply. At maturity, alpha-amylase, grain area and endosperm cavity area were measured in individual grains. Both cold and heat shocks were successful in inducing premature alpha-amylase in susceptible genotypes, with cold shocks the ...
Scientific Reports, 2014
To study the role of abscisic acid (ABA) and gibberellins (GA) in pre-maturity a-amylase (PMA) fo... more To study the role of abscisic acid (ABA) and gibberellins (GA) in pre-maturity a-amylase (PMA) formation in developing wheat grain, two glasshouse experiments were conducted under controlled conditions in the highly PMA-susceptible genotype Rialto. The first, determined the relative efficacy of applying hormone solutions by injection into the peduncle compared to direct application to the intact grain. The second, examined the effects of each hormone, applied by either method, at mid-grain development on PMA in mature grains. In the first experiment, tritiated ABA ( 3 H-ABA) and gibberellic acid ( 3 H-GA 3 ) were diluted with unlabelled ABA (100 mM) and GA 3 (50 mM), respectively, and applied at mid-grain development using both methods. Spikes were harvested after 24, 48 and 72 h from application, and hormone taken up by grains was determined. After 72 h, the uptake per grain in terms of hormones applied was approximately 13% for ABA and 8% for GA 3 when applied onto the grains, and approximately 17% for ABA and 5% for GA 3 when applied by injection. In the second experiment, applied ABA reduced, whereas applied GA 3 increased a-amylase activity. This confirmed that exogenously applied ABA and GA were absorbed in sufficient amounts to alter grain metabolism and impact on PMA. E xogenous hormone application is an important experimental technique for helping to understand the hormonal control of plant growth and development. Different methods have been used to study the effects of exogenous hormones on grain development. A few studies have dealt with pre-anthesis hormone regulation of floret development 31 , whereas most studies investigated grain development after anthesis 22 . Generally in cereals, abscisic acid (ABA) and gibberellic acid (GA 3 ) solutions have been applied separately either by spraying onto the leaves and spikes 1,7,31-32 or by injecting into the leaf sheath 31 to study their role in floret development, grain set and filling. Yang et al. 32 applied ABA (20 mM) by spraying the leaves and panicles in two rice cultivars, Wuyujing 3 and Yangdao 4, daily for 7 days starting at 9 days after anthesis (DAA), and observed a 3-to 4-fold increase in ABA levels in grains at 12 and 20 DAA in ABA-treated plants compared to plants treated with water in both cultivars. Similar results were reported later by , after spraying ABA (20 mM) solution onto the panicles of rice plants daily for 8 days starting at the initiation of heading, and ABA levels in grains were measured at 9 and 16 DAA. They observed that an increase in the endogenous ABA levels in grains was about 4-fold at 9 DAA and 2-fold at 16 DAA in ABA-treated plants compared to plants treated with water. In both studies, ABA was quantified by the enzyme-linked immunosorbent assay (ELISA) using mouse monoclonal antibodies against ABA. This shows that a substantial amount of applied ABA reaches the grain in a biological active form. The role of ABA and gibberellins (GA) in regulating a-amylase formation in germinating and pre-harvest sprouted wheat grains is well documented in the literature . However, their role in regulating pre-maturity a-amylase (PMA) synthesis in intact, developing wheat grains is less well known. In order to determine the role of ABA and GA in a-amylase formation in developing grains, it is necessary to investigate the most effective method for in situ hormone application to ensure that the applied hormones are being taken up by the grains.
Euphytica, 2002
Dormancy of wheat grains, the property conferring sprouting resistance, is affected by environmen... more Dormancy of wheat grains, the property conferring sprouting resistance, is affected by environmental conditions experienced during grain development. We investigated the hypothesis that short dormancy duration in U.K. wheat grain (thus a high risk of post-maturity sprouting) is related to weather conditions, i.e. high temperatures during grain development. Four wheat varieties were grown at four sites ranging from the far
The Journal of Agricultural Science, 2008
Previous work has shown that the national average quality of the UK wheat crop from 1974 to 1999 ... more Previous work has shown that the national average quality of the UK wheat crop from 1974 to 1999 was associated with the preceding winter North Atlantic Oscillation (NAO). The association of the winter NAO with the grain quality measure, specific weight, was shown to be mediated by sunshine duration during grain filling and unconditional wet day probability during grain ripening (the probability of a wet day following either a dry or a wet day). The present study tests the hypothesis that the association between specific weight and the winter NAO can be detected in data from 158 years of the Broadbalk Wheat Experiment at Rothamsted in south-east England. Specific weight from the Broadbalk Experiment responded to sunshine duration during grain filling and unconditional wet day probability during grain ripening in a similar way to the national average data. An association with the winter NAO was found in the Broadbalk data from 1956 to 2001, but not in the previous 112 years . This finding is consistent with other work showing significant correlations between the winter NAO and summer climate only in recent decades. It is concluded that the association between wheat quality and the NAO is a recent phenomenon.
The Journal of Agricultural Science, 2012
ABSTRACT Four field experiments were conducted on wheat, using the bread-making cultivar Hereward... more ABSTRACT Four field experiments were conducted on wheat, using the bread-making cultivar Hereward, over 3 years to study the interactions between nitrogen (N) and strobilurin fungicides with respect to yield and grain N. In one of the field experiments, above-ground dry matter (DM) yield was greater when the plots were treated with a mixture of triazole and strobilurin than when either no fungicide or triazole alone was applied. On plots that received no N fertilizer, above-ground DM and grain yield were lower for the plots treated with fungicides than for plots not treated with fungicide, which implied that the benefit of applying fungicides could only be exploited with N fertilization. There was no difference in above-ground N accumulation between fungicide programmes; however, greater N accumulation in grains was observed following the application of a mixture of triazole and the strobilurin trifloxystrobin compared with plots treated with either no fungicide or triazole alone. This increase in grain N appeared to be attributable more to improved translocation of N to grains rather than to increased N uptake from the soil. The two strobilurin fungicide ingredients kresoxim-methyl and trifloxystrobin, each mixed with a triazole and tested in the present study, performed differently. Better performance, especially with respect to grain N yield, was observed most frequently with trifloxystrobin compared to kresoxim-methyl.
The Journal of Agricultural Science, 1983
... BY PS KETTLEWELL, ELERI A. WHITLEY*, WS MEREDITHf Harper Adams Agricultural College, Newport,... more ... BY PS KETTLEWELL, ELERI A. WHITLEY*, WS MEREDITHf Harper Adams Agricultural College, Newport, Shropshire, TF10 8NB AND R. SYLVESTER-BRADLEY Plant Physiology Unit, Ministry of Agriculture, Fisheries and Food, Woodthorne, Wolverhampton, WVQ 8TQ ...
The Journal of Agricultural Science, 1997
ABSTRACT The hypothesis was tested that slow grain drying stimulates pre-maturity alpha-amylase a... more ABSTRACT The hypothesis was tested that slow grain drying stimulates pre-maturity alpha-amylase activity in wheat (Triticum aestivum L.). Grain drying rate in 91 commercial crops of cultivars Avalon or Mercia grown over the years 1988–90 was estimated from the slope of linear regressions of moisture content on time. Incipient sprouting was detected in some samples from 1988 using the fluoroscein dibutyrate test, but results from a beta-limit dextrin gel assay indicated that pre-maturity alpha-amylase was probably the major source of alpha-amylase activity in these samples. Although year-to-year differences in ln alpha-amylase activity and Hagberg falling number tended to be associated with seasonal differences in drying rate, there was no evidence of a relationship between either ln alpha-amylase activity or Hagberg falling number and drying rate after the year effect was removed by an analysis of covariance. A second dataset from one crop in each of 14 years at one site showed significant positive linear relationships between cumulative potential evapotranspiration calculated over different periods during grain ripening and Hagberg falling number (excluding 3 years when incipient sprouting was thought to occur). It was concluded that pre-maturity alpha-amylase activity was stimulated by an unknown environmental factor differing between seasons and associated with seasonal differences in drying rate and cumulative potential evapotranspiration.
The Journal of Agricultural Science, 1997
... Draper 1982). This, therefore, can explain the negative relationship between HFN and August r... more ... Draper 1982). This, therefore, can explain the negative relationship between HFN and August rainfall. Delayed drying of the grain may also reduce HFN in the absence of sprouting (Gale et al. 1983; Gooding et al. 1994), which ...
The Journal of Agricultural Science, 2006
The Journal of Agricultural Science, 1986
ABSTRACT
The Journal of Agricultural Science, 2002
ABSTRACT Supplying a proportion of the N requirement of a wheat crop via the foliage would potent... more ABSTRACT Supplying a proportion of the N requirement of a wheat crop via the foliage would potentially reduce immobilization of fertilizer N in the soil organic matter and N losses by leaching or denitrification. A field experiment was carried out at Harper Adams in Shropshire to investigate the effect on crop yield of supplying the spring N application to winter wheat as different proportions of urea as a solution rather than as conventional soil-applied urea, and to determine the physiological basis of any yield differences. A solid ammonium nitrate treatment was included to represent alternative commercial practice to solid urea. Treatments were repeated on the same plots over the 3 years 1992, 1993 and 1994. Solid fertilizer was applied as a single dressing, whereas urea sprays were split over a number of days to reduce scorch. Nitrogen as urea sprays produced similar grain yields to N applied conventionally to the soil as solid ammonium nitrate or urea, but effects on above-ground dry matter production and harvest index depended on the time of application. Application of a large proportion of N as urea sprays, such that some of the N as urea solution was applied later in relation to crop development, produced less above-ground dry matter, but compensated by increasing harvest index. It is concluded that application of N as urea sprays could be successfully used to substitute for soil-applied N fertilizer at stem extension in winter wheat without loss of yield. Extra application costs, however, are likely to outweigh any efficiency or environmental benefits, except where applications of solid N are made to dry soils.
The Journal of Agricultural Science, 1991
... to obtain maximum yield (Sylvester-Bradley et al. 1984). The yield increase by urea in Shrops... more ... to obtain maximum yield (Sylvester-Bradley et al. 1984). The yield increase by urea in Shropshire 1985, however, contrasts with this trend because an adjacent ex-periment showed that the application of nitrogen fertilizer in the spring was optimal for yield (Gooding 1988). ...
The Journal of Agricultural Science, 1995
ABSTRACT Elemental sulphur (32 kg S/ha) and urea (30 kg N/ha) were applied to the foliage of diff... more ABSTRACT Elemental sulphur (32 kg S/ha) and urea (30 kg N/ha) were applied to the foliage of different winter wheat cultivars, halfat flag leaf emergence and halfat ear emergence, in factorial experiments in 1986, 1987 and 1988. There were no clear visual symptoms of S deficiency, but there was evidence from soil analysis, grain S concentration and grain N:S ratio that the crops were marginally deficient in sulphur. Disease severity was generally negligible. Leaf senescence at the end of grain growth was delayed by sulphur in two of the three years, both with and without urea in 1987, but only with urea in 1988. Sulphur, both alone and mixed with urea, increased grain S concentration from early grain growth in 1986 and 1987, but not until the end of grain growth in 1988. Urea alone reduced yield in 1986 and 1987, but mixing S with the urea compensated for this phytotoxic effect. Yield was not significantly increased by S when compared with plots receiving neither urea nor S.
The Journal of Agricultural Science, 1982
The Journal of Agricultural Science, 2007