Chickpea is a new crop in Kenya and its potential has not been fully utilized. The chickpea grain... more Chickpea is a new crop in Kenya and its potential has not been fully utilized. The chickpea grain yields generally range between 1.2 to 3.5 tons/ha at farmers‟ fields, indicating that chickpea has a potential of becoming an important export crop in Kenya. The chickpea breeding program in Kenya is still at infant stage and being established with support from International Crops Research Institute for the Semi-Arid Tropics (ICRISAT). Four chickpea varieties have been recently released from the breeding material supplied by ICRISAT. Efforts are being made on evaluation of germplasm and breeding lines, application of modern molecular breeding tools and techniques in chickpea breeding and establishment of effective seed system for establishing a sustainable chickpea production system in the country.
Finger millet is a staple, high-quality food, important to the livelihoods of millions of smallho... more Finger millet is a staple, high-quality food, important to the livelihoods of millions of smallholder farmers in East Africa. It has been neglected by major donors to agricultural research. This paper reports recent investment by the UK Department for International Development (DFID) in several projects on blast disease that has not only led to successful promotion of sound blast management strategies to farmers, but has also fostered partnerships in an evolving finger millet innovation system in East Africa. A key entry point has been created to address other constraints to finger millet production and utilization, such as ineffective weed management, poor grain quality, inefficient seed systems and production–supply chain problems, notably through‘spill-in’ and adaptation of relevant technologies developed elsewhere. Further donor investment in the finger millet sector is likely to make a significant contribution to fighting malnutrition and poverty in East Africa.
Chickpea ( Cicer arietinum ) is an edible legume grown widely for its nutritious seed, which is r... more Chickpea ( Cicer arietinum ) is an edible legume grown widely for its nutritious seed, which is rich in protein, minerals, vitamins and dietary fibre. It’s a new crop in Kenya whose potential has not been utilized fully due to abiotic and biotic stresses that limit its productivity. The crop is affected mainly by Ascochyta blight (AB) which is widespread in cool dry highlands causing up to 100% yield loss. The objective of this study was to evalu- ate the resistance of selected chickpea genotypes to AB in dry highlands of Kenya. The study was done in 2 sites (Egerton University-Njoro) and Agricultural Training centre-ATC-Koibatek) for one season during long rains of 2010/2011 growing season. Thirty six genotypes from reference sets and mini-core samples introduced from ICR- SAT were evaluated. There were significant (P 1200 Kg ha-1. The findings of the study showed that chickpea should be sown during the short rains (summer) in the dry highlands of Kenya when conditions are drier an...
Traditionally, chickpea is grown as a winter crop with in-crop rain or stored soil moisture, or a... more Traditionally, chickpea is grown as a winter crop with in-crop rain or stored soil moisture, or as a spring crop using residual stored soil moisture. In the semi-arid tropics, it is grown when rainfall is tapering off in the late rainy season and utilises moisture stored in the soil profile. These growing conditions are characterised by a gradual decline in soil moisture towards the end of the growing season leading to terminal drought. Drought causes up to 50% yield losses in chickpea, however, depending on the genotype, environment, and type of drought experienced, seed yield losses can range from 30-100%. The effect of drought will be exacerbated by global warming which is projected to be responsible for a 20% increase in water shortages in drought prone areas. Since 80% of the world's allocable water is consumed in irrigated agriculture, and water resources for agriculture are generally decreasing, it may not be feasible to grow chickpeas under irrigation to mitigate the effect of drought. Breeding cultivars with high water use efficiency (WUE) is a more practical and economical long-term approach to increasing yields in drought prone areas. WUE leads to moderate water uptake while maintaining increased yields under drought conditions making WUE an integral part of breeding programs. Any modifications above the soil surface have an effect on WUE since it impacts on the soil water balance via soil water evaporation and infiltration. This necessitates the incorporation of management practices, such as tillage, in studies analysing WUE. Since WUE is a complex trait, secondary traits that are easy to measure and that have genetic variation, high heritability and are associated with yield under water-limited conditions make breeding for WUE easier. Little attention has been paid to the pattern of water use in legumes and the relationship between water used, WUE and seed yield. Despite evaluation of WUE in chickpea in various studies, little has been achieved as those studies focused on single factors affecting WUE, which caused variability in outcomes due to a failure to integrate other factors. The central research question of this study was: can chickpea yields be sustained by increased water use efficiency under drought conditions? The aims of this thesis were to study the genetic variation underpinning WUE and grain yield in different tillage and irrigation regimes, as well as the basis of yield formation under water limited conditions. Water use and WUE are important traits under water-limited conditions. It was hypothesised that genotypes with high WUE would produce high yields under water-limited conditions. For this hypothesis to be tested, a total of 36 entries were planted in the field at the IA Watson Plant iv Breeding Institute, The University of Sydney in Narrabri, northwest New South Wales in Australia. Water use was monitored using a neutron probe moisture meter and WUE calculated using the soil water balance method. Grain yield was higher under irrigation (1722 kg ha-1) than rainfed conditions (1478 kg ha-1). No till plots resulted in an average yield of 1658 kg ha-1 which was 7.4% higher than in the till regime. There were no significant differences in water use; however, there were significant differences for WUE. WUE was higher under no till (5.02 kg ha-1 mm-1 than under till (4.87kg ha-1 mm-1), and higher under irrigation (5.05 kg ha-1 mm-1) than under rainfed conditions (4.84 kg ha-1 mm-1). Sonali was the highest yielding genotype and also had the best WUE. Identifying drought tolerant genotypes to be used as sources of tolerance in a breeding program is imperative. Traits that can confer drought tolerance under field conditions should be considered instead of yield alone. It was hypothesised that drought selection indices differ in their prediction accuracy and that some indices can be used to predict marker traits that can confer tolerance to drought in the field. To test this hypothesis, phenological, morphological, physiological and yield component data were analysed from the experiments performed in Narrabri. Drought indices were calculated and multiple linear regression was used to identify the most important traits that explained variation in yield. The stress tolerance index, mean relative performance and relative efficiency index were highly and positively associated with yield. These three traits were identified as the most effective indices for use in chickpea using principal component analysis compared with drought resistance index, yield index and yield stability index, which were not as suitable. Sonali, ICCV 96853 and PBA Slasher were identified as drought tolerant genotypes whereas Amethyst and Genesis 079 were identified as susceptible to drought. A total of 21 traits (Agyeman et al., 2015) out of 40 were identified as important in drought tolerance. The indices identified normalised difference vegetation index (NDVI) at early podding and late podding, as well as chlorophyll content at late podding, as useful marker traits to identify genotypes with potentially high yield and high drought tolerance. Sustaining yield under different environments is important for the grower as well as the plant breeder. Genotype by environment interaction affects varietal ability to sustain yields across environments. It was hypothesised that there would be a significant genotype by environment interaction and hence, yield would not be stable across environments. To test this, 36 genotypes were sown using a two factorial experimental design in two seasons under no till, with and without irrigation, and till, with and without irrigation, in Narrabri making a total of eight v environments. The data were analysed using restricted maximum likelihood (REML) to check for genotype by environment interaction as well as genotype and genotype by environment interaction (Staggenborg and Vanderlip) biplot analysis to identify stable and high yielding genotypes. There was a significant genotype by environment interaction and genotype performance varied with environment. Generally, the yields in 2014 were higher than those in 2015 with 58% of the variation in yield accounted for by the year (season) effect. No till with irrigation in 2014 resulted in the highest average yield and till rainfed in 2015 resulted in the lowest mean yield. Some genotypes were more stable and high yielding than others. PBA Slasher and ICCV 96853 were high yielding and stable, whereas Genesis 079 was high yielding and very unstable. Sonali and Amethyst had moderate stability. The plant ideotype approach is an alternative strategy to empirical breeding and allows the breeder to predict the ideal genotype in the target environment. Each ideotype is designed to grow in a defined target environment, hence, it is important to characterise the environment. It was hypothesised that selecting for key plant traits can confer drought tolerance and that abiotic stress sensitivity varies across plant phenophases. To test these hypotheses, data generated from the Narrabri field experiment was used. The key phenological, morphological and physiological traits were determined for ideotype targeting using multiple linear regression and ideotype values assigned depending on trait relationship with yield and other traits. The ideotype was then tested against selected commercial varieties (Sonali, PBA Hattrick, Kyabra, Tyson and Amethyst) in silico in the Australian grain belt using the APSIM crop model. The constructed chickpea ideotype showed 76% resemblance to Sonali which performed well under water-limited conditions. Simulated yield ranged from 760 to 3902 kg ha-1 across the Australian grain belt, with consistently higher yield in the ideotype compared with the commercial cultivars. The growing environments were grouped into three major clusters using the soil water deficit method with varying water stress levels. Grain filling is the most critical stage where soil moisture deficit caused chickpea yield loss. By incorporating key target traits and targeting the right environment, chickpea yields can be sustained. This study shows that there is genetic variation for WUE and it is a major component of drought tolerance. By identifying drought tolerant genotypes which are high yielding and stable, yields may be sustained under water limited conditions. By targeting a chickpea ideotype for specific environments, plant breeders can have a more focused strategy and hence, faster delivery of technologies to develop cultivars that are suitable for the target environment vi Table of contents ABSTRACT .
Crop varieties interact with the environment, which affects their performance. It is imperative t... more Crop varieties interact with the environment, which affects their performance. It is imperative to know how the environment affects these crop varieties in order to choose carefully the optimal environment for growth. Chickpea (Cicer arietinum L.) is grown in varying environmental conditions including conventional and no-tillage under both irrigated and rainfed farming systems. Hence, genotype × environment × management interactions can affect yield stability. An experiment was conducted in north-western New South Wales, Australia, to investigate these interactions and to determine possible environment types to help focus crop improvement. Eight environments were considered and genotype plus genotype × environment interaction (GGE) biplots were generated to assess genotype stability and interactions with environment. Genotype and environment main effects and genotype × environment interactions (GEI) accounted for 12.6%, 66% and 12% of the total variation in yield, respectively. The ...
Abiotic and Biotic Stress in Plants [Working Title], 2019
Chickpea is an important legume providing dietary proteins to both humans and animals. It also am... more Chickpea is an important legume providing dietary proteins to both humans and animals. It also ameliorates soil nitrogen through biological nitrogen fixation. Drought, heat and cold are important factors among abiotic stresses limiting production in chickpea. Identification, validation and integration of agronomic, physiological and biochemical traits into breeding programs could lead to increased rates of genetic gain and the development of better adapted cultivars to abiotic stress conditions. This chapter illustrates the effects of stresses on chickpea growth and development. It also reviews the various traits and their relationship with grain yield under stress and proposes recommendation for future breeding.
Terminal drought is a major problem in many areas where chickpea is grown on stored soil moisture... more Terminal drought is a major problem in many areas where chickpea is grown on stored soil moisture. This is exacerbated by the lack of a targeted breeding approach focusing on key traits contributing to yield formation under water-limited conditions. There is no study to develop a chickpea ideotype and test it against commercial varieties under various management systems across the Australian grain belt. This study proposed a chickpea ideotype that can be grown in water deficit areas and compared its performance with commercial chickpea genotypes across the Australian grain belt. Important traits for ideotype construction and breeding were identified and tested against selected commercial varieties in silico in the Australian grain belt using the APSIM crop model. The key phenological, morphological and physiological traits were determined in the field at the University of Sydney's IA Watson Grains Research Centre near Narrabri for ideotype targeting. Five commercial chickpea genotypes (Sonali, PBA Hattrick, Kyabra, Tyson and Amethyst) were selected for evaluation against the chickpea ideotype. The constructed chickpea ideotype showed 76% resemblance to Sonali which performed well under water limited conditions. Simulated yield ranged from 760 to 3902 kg/ha across the Australian grain belt, with consistently higher yield in the ideotype compared with the commercial cultivars. The growing environments were grouped into three major clusters using the soil water deficit method with varying water stress levels. It is evident that grain filling is the most critical stage where soil moisture deficit caused chickpea yield losses up to 16.5% in the present study. By incorporating key target traits and targeting the right environment, chickpea yields can be sustained in the Australian grain belt or in an area having similar agro-ecological characteristics.
Yields of grain legumes are constrained by available water. Thus, it is crucial to understand tra... more Yields of grain legumes are constrained by available water. Thus, it is crucial to understand traits influencing water uptake and the efficiency of using water to produce biomass. Global comparisons and comparisons at specific locations reveal that water use of different grain legumes is very similar, which indicates that water use efficiency varies over a wide range due to differences in biomass and yield. Moreover, yield increases more per millimetre of water used in cool season grain legumes than warm season species. Although greater contrasts have been observed across species and genotypes at the pot and lysimeter level, agronomic factors need to be taken into account when scaling those studies to field-level responses. Conservative water use strategies in grain legumes such as low stomatal conductance as approximated by low photosynthetic carbon isotope discrimination reduces yield potential, whereas temporal adjustments of stomatal conductance within the growing season and in response to environmental factors (such as vapour pressure deficit) helps to optimize the trade-off between carbon gain and water loss. Furthermore, improved photosynthetic capacity, reduced mesophyll conductance, reduced boundary layer, and re-fixation of respired CO 2 were identified as traits that are beneficial without water deficit, but also under terminal and transient drought. Genotypic variability in some grain legume species has been observed for several traits that influence water use, water use efficiency, and yield, including root length and the temporal pattern of water use, but even more variation is expected from wild relatives. Albeit that N 2 fixation decreases under drought, its impact on water use is still largely unknown, but the nitrogen source influences gas exchange and, thus, transpiration efficiency. This review concludes that conservative traits are needed under conditions of terminal drought to help maintain soil moisture until the pod-filling period, but profligate traits, if tightly regulated, are important under conditions of transient drought in order to profit from short intermittent periods of available soil moisture.
Chickpea is a new crop in Kenya and its potential has not been fully utilized. The chickpea grain... more Chickpea is a new crop in Kenya and its potential has not been fully utilized. The chickpea grain yields generally range between 1.2 to 3.5 tons/ha at farmers‟ fields, indicating that chickpea has a potential of becoming an important export crop in Kenya. The chickpea breeding program in Kenya is still at infant stage and being established with support from International Crops Research Institute for the Semi-Arid Tropics (ICRISAT). Four chickpea varieties have been recently released from the breeding material supplied by ICRISAT. Efforts are being made on evaluation of germplasm and breeding lines, application of modern molecular breeding tools and techniques in chickpea breeding and establishment of effective seed system for establishing a sustainable chickpea production system in the country.
Finger millet is a staple, high-quality food, important to the livelihoods of millions of smallho... more Finger millet is a staple, high-quality food, important to the livelihoods of millions of smallholder farmers in East Africa. It has been neglected by major donors to agricultural research. This paper reports recent investment by the UK Department for International Development (DFID) in several projects on blast disease that has not only led to successful promotion of sound blast management strategies to farmers, but has also fostered partnerships in an evolving finger millet innovation system in East Africa. A key entry point has been created to address other constraints to finger millet production and utilization, such as ineffective weed management, poor grain quality, inefficient seed systems and production–supply chain problems, notably through‘spill-in’ and adaptation of relevant technologies developed elsewhere. Further donor investment in the finger millet sector is likely to make a significant contribution to fighting malnutrition and poverty in East Africa.
Chickpea ( Cicer arietinum ) is an edible legume grown widely for its nutritious seed, which is r... more Chickpea ( Cicer arietinum ) is an edible legume grown widely for its nutritious seed, which is rich in protein, minerals, vitamins and dietary fibre. It’s a new crop in Kenya whose potential has not been utilized fully due to abiotic and biotic stresses that limit its productivity. The crop is affected mainly by Ascochyta blight (AB) which is widespread in cool dry highlands causing up to 100% yield loss. The objective of this study was to evalu- ate the resistance of selected chickpea genotypes to AB in dry highlands of Kenya. The study was done in 2 sites (Egerton University-Njoro) and Agricultural Training centre-ATC-Koibatek) for one season during long rains of 2010/2011 growing season. Thirty six genotypes from reference sets and mini-core samples introduced from ICR- SAT were evaluated. There were significant (P 1200 Kg ha-1. The findings of the study showed that chickpea should be sown during the short rains (summer) in the dry highlands of Kenya when conditions are drier an...
Traditionally, chickpea is grown as a winter crop with in-crop rain or stored soil moisture, or a... more Traditionally, chickpea is grown as a winter crop with in-crop rain or stored soil moisture, or as a spring crop using residual stored soil moisture. In the semi-arid tropics, it is grown when rainfall is tapering off in the late rainy season and utilises moisture stored in the soil profile. These growing conditions are characterised by a gradual decline in soil moisture towards the end of the growing season leading to terminal drought. Drought causes up to 50% yield losses in chickpea, however, depending on the genotype, environment, and type of drought experienced, seed yield losses can range from 30-100%. The effect of drought will be exacerbated by global warming which is projected to be responsible for a 20% increase in water shortages in drought prone areas. Since 80% of the world's allocable water is consumed in irrigated agriculture, and water resources for agriculture are generally decreasing, it may not be feasible to grow chickpeas under irrigation to mitigate the effect of drought. Breeding cultivars with high water use efficiency (WUE) is a more practical and economical long-term approach to increasing yields in drought prone areas. WUE leads to moderate water uptake while maintaining increased yields under drought conditions making WUE an integral part of breeding programs. Any modifications above the soil surface have an effect on WUE since it impacts on the soil water balance via soil water evaporation and infiltration. This necessitates the incorporation of management practices, such as tillage, in studies analysing WUE. Since WUE is a complex trait, secondary traits that are easy to measure and that have genetic variation, high heritability and are associated with yield under water-limited conditions make breeding for WUE easier. Little attention has been paid to the pattern of water use in legumes and the relationship between water used, WUE and seed yield. Despite evaluation of WUE in chickpea in various studies, little has been achieved as those studies focused on single factors affecting WUE, which caused variability in outcomes due to a failure to integrate other factors. The central research question of this study was: can chickpea yields be sustained by increased water use efficiency under drought conditions? The aims of this thesis were to study the genetic variation underpinning WUE and grain yield in different tillage and irrigation regimes, as well as the basis of yield formation under water limited conditions. Water use and WUE are important traits under water-limited conditions. It was hypothesised that genotypes with high WUE would produce high yields under water-limited conditions. For this hypothesis to be tested, a total of 36 entries were planted in the field at the IA Watson Plant iv Breeding Institute, The University of Sydney in Narrabri, northwest New South Wales in Australia. Water use was monitored using a neutron probe moisture meter and WUE calculated using the soil water balance method. Grain yield was higher under irrigation (1722 kg ha-1) than rainfed conditions (1478 kg ha-1). No till plots resulted in an average yield of 1658 kg ha-1 which was 7.4% higher than in the till regime. There were no significant differences in water use; however, there were significant differences for WUE. WUE was higher under no till (5.02 kg ha-1 mm-1 than under till (4.87kg ha-1 mm-1), and higher under irrigation (5.05 kg ha-1 mm-1) than under rainfed conditions (4.84 kg ha-1 mm-1). Sonali was the highest yielding genotype and also had the best WUE. Identifying drought tolerant genotypes to be used as sources of tolerance in a breeding program is imperative. Traits that can confer drought tolerance under field conditions should be considered instead of yield alone. It was hypothesised that drought selection indices differ in their prediction accuracy and that some indices can be used to predict marker traits that can confer tolerance to drought in the field. To test this hypothesis, phenological, morphological, physiological and yield component data were analysed from the experiments performed in Narrabri. Drought indices were calculated and multiple linear regression was used to identify the most important traits that explained variation in yield. The stress tolerance index, mean relative performance and relative efficiency index were highly and positively associated with yield. These three traits were identified as the most effective indices for use in chickpea using principal component analysis compared with drought resistance index, yield index and yield stability index, which were not as suitable. Sonali, ICCV 96853 and PBA Slasher were identified as drought tolerant genotypes whereas Amethyst and Genesis 079 were identified as susceptible to drought. A total of 21 traits (Agyeman et al., 2015) out of 40 were identified as important in drought tolerance. The indices identified normalised difference vegetation index (NDVI) at early podding and late podding, as well as chlorophyll content at late podding, as useful marker traits to identify genotypes with potentially high yield and high drought tolerance. Sustaining yield under different environments is important for the grower as well as the plant breeder. Genotype by environment interaction affects varietal ability to sustain yields across environments. It was hypothesised that there would be a significant genotype by environment interaction and hence, yield would not be stable across environments. To test this, 36 genotypes were sown using a two factorial experimental design in two seasons under no till, with and without irrigation, and till, with and without irrigation, in Narrabri making a total of eight v environments. The data were analysed using restricted maximum likelihood (REML) to check for genotype by environment interaction as well as genotype and genotype by environment interaction (Staggenborg and Vanderlip) biplot analysis to identify stable and high yielding genotypes. There was a significant genotype by environment interaction and genotype performance varied with environment. Generally, the yields in 2014 were higher than those in 2015 with 58% of the variation in yield accounted for by the year (season) effect. No till with irrigation in 2014 resulted in the highest average yield and till rainfed in 2015 resulted in the lowest mean yield. Some genotypes were more stable and high yielding than others. PBA Slasher and ICCV 96853 were high yielding and stable, whereas Genesis 079 was high yielding and very unstable. Sonali and Amethyst had moderate stability. The plant ideotype approach is an alternative strategy to empirical breeding and allows the breeder to predict the ideal genotype in the target environment. Each ideotype is designed to grow in a defined target environment, hence, it is important to characterise the environment. It was hypothesised that selecting for key plant traits can confer drought tolerance and that abiotic stress sensitivity varies across plant phenophases. To test these hypotheses, data generated from the Narrabri field experiment was used. The key phenological, morphological and physiological traits were determined for ideotype targeting using multiple linear regression and ideotype values assigned depending on trait relationship with yield and other traits. The ideotype was then tested against selected commercial varieties (Sonali, PBA Hattrick, Kyabra, Tyson and Amethyst) in silico in the Australian grain belt using the APSIM crop model. The constructed chickpea ideotype showed 76% resemblance to Sonali which performed well under water-limited conditions. Simulated yield ranged from 760 to 3902 kg ha-1 across the Australian grain belt, with consistently higher yield in the ideotype compared with the commercial cultivars. The growing environments were grouped into three major clusters using the soil water deficit method with varying water stress levels. Grain filling is the most critical stage where soil moisture deficit caused chickpea yield loss. By incorporating key target traits and targeting the right environment, chickpea yields can be sustained. This study shows that there is genetic variation for WUE and it is a major component of drought tolerance. By identifying drought tolerant genotypes which are high yielding and stable, yields may be sustained under water limited conditions. By targeting a chickpea ideotype for specific environments, plant breeders can have a more focused strategy and hence, faster delivery of technologies to develop cultivars that are suitable for the target environment vi Table of contents ABSTRACT .
Crop varieties interact with the environment, which affects their performance. It is imperative t... more Crop varieties interact with the environment, which affects their performance. It is imperative to know how the environment affects these crop varieties in order to choose carefully the optimal environment for growth. Chickpea (Cicer arietinum L.) is grown in varying environmental conditions including conventional and no-tillage under both irrigated and rainfed farming systems. Hence, genotype × environment × management interactions can affect yield stability. An experiment was conducted in north-western New South Wales, Australia, to investigate these interactions and to determine possible environment types to help focus crop improvement. Eight environments were considered and genotype plus genotype × environment interaction (GGE) biplots were generated to assess genotype stability and interactions with environment. Genotype and environment main effects and genotype × environment interactions (GEI) accounted for 12.6%, 66% and 12% of the total variation in yield, respectively. The ...
Abiotic and Biotic Stress in Plants [Working Title], 2019
Chickpea is an important legume providing dietary proteins to both humans and animals. It also am... more Chickpea is an important legume providing dietary proteins to both humans and animals. It also ameliorates soil nitrogen through biological nitrogen fixation. Drought, heat and cold are important factors among abiotic stresses limiting production in chickpea. Identification, validation and integration of agronomic, physiological and biochemical traits into breeding programs could lead to increased rates of genetic gain and the development of better adapted cultivars to abiotic stress conditions. This chapter illustrates the effects of stresses on chickpea growth and development. It also reviews the various traits and their relationship with grain yield under stress and proposes recommendation for future breeding.
Terminal drought is a major problem in many areas where chickpea is grown on stored soil moisture... more Terminal drought is a major problem in many areas where chickpea is grown on stored soil moisture. This is exacerbated by the lack of a targeted breeding approach focusing on key traits contributing to yield formation under water-limited conditions. There is no study to develop a chickpea ideotype and test it against commercial varieties under various management systems across the Australian grain belt. This study proposed a chickpea ideotype that can be grown in water deficit areas and compared its performance with commercial chickpea genotypes across the Australian grain belt. Important traits for ideotype construction and breeding were identified and tested against selected commercial varieties in silico in the Australian grain belt using the APSIM crop model. The key phenological, morphological and physiological traits were determined in the field at the University of Sydney's IA Watson Grains Research Centre near Narrabri for ideotype targeting. Five commercial chickpea genotypes (Sonali, PBA Hattrick, Kyabra, Tyson and Amethyst) were selected for evaluation against the chickpea ideotype. The constructed chickpea ideotype showed 76% resemblance to Sonali which performed well under water limited conditions. Simulated yield ranged from 760 to 3902 kg/ha across the Australian grain belt, with consistently higher yield in the ideotype compared with the commercial cultivars. The growing environments were grouped into three major clusters using the soil water deficit method with varying water stress levels. It is evident that grain filling is the most critical stage where soil moisture deficit caused chickpea yield losses up to 16.5% in the present study. By incorporating key target traits and targeting the right environment, chickpea yields can be sustained in the Australian grain belt or in an area having similar agro-ecological characteristics.
Yields of grain legumes are constrained by available water. Thus, it is crucial to understand tra... more Yields of grain legumes are constrained by available water. Thus, it is crucial to understand traits influencing water uptake and the efficiency of using water to produce biomass. Global comparisons and comparisons at specific locations reveal that water use of different grain legumes is very similar, which indicates that water use efficiency varies over a wide range due to differences in biomass and yield. Moreover, yield increases more per millimetre of water used in cool season grain legumes than warm season species. Although greater contrasts have been observed across species and genotypes at the pot and lysimeter level, agronomic factors need to be taken into account when scaling those studies to field-level responses. Conservative water use strategies in grain legumes such as low stomatal conductance as approximated by low photosynthetic carbon isotope discrimination reduces yield potential, whereas temporal adjustments of stomatal conductance within the growing season and in response to environmental factors (such as vapour pressure deficit) helps to optimize the trade-off between carbon gain and water loss. Furthermore, improved photosynthetic capacity, reduced mesophyll conductance, reduced boundary layer, and re-fixation of respired CO 2 were identified as traits that are beneficial without water deficit, but also under terminal and transient drought. Genotypic variability in some grain legume species has been observed for several traits that influence water use, water use efficiency, and yield, including root length and the temporal pattern of water use, but even more variation is expected from wild relatives. Albeit that N 2 fixation decreases under drought, its impact on water use is still largely unknown, but the nitrogen source influences gas exchange and, thus, transpiration efficiency. This review concludes that conservative traits are needed under conditions of terminal drought to help maintain soil moisture until the pod-filling period, but profligate traits, if tightly regulated, are important under conditions of transient drought in order to profit from short intermittent periods of available soil moisture.
Uploads
Papers by Peter Kaloki