High-throughput field crop phenotyping: current status and challenges

In contrast to the rapid advances made in plant genotyping, plant phenotyping is considered a bottleneck in plant science. This has promoted high-throughput plant phenotyping (HTP) studies, resulting in an exponential increase in phenotyping-related publications. The development of HTP was originally intended for use as indoor HTP technologies for model plant species under controlled environments. However, this subsequently shifted to HTP for use in crops in fields. Although HTP in fields is much more difficult to conduct due to unstable environmental conditions compared to HTP in controlled environments, recent advances in HTP technology have allowed these difficulties to be overcome, allowing for rapid, efficient, non-destructive, non-invasive, quantitative, repeatable, and objective phenotyping. Recent HTP developments have been accelerated by the advances in data analysis, sensors, and robot technologies, including machine learning, image analysis, three dimensional (3D) reconstruction, image sensors, laser sensors, environmental sensors, and drones, along with high-speed computational resources. This article provides an overview of recent HTP technologies, focusing mainly on canopy-based phenotypes of major crops, such as canopy height, canopy coverage, canopy biomass, and canopy stressed appearance, in addition to crop organ detection and counting in the fields. Current topics in field HTP are also presented, followed by a discussion on the low rates of adoption of HTP in practical breeding programs.     

Identifying lettuce species (Lactuca subsect. Lactuca, Asteraceae): A practical application of flow cytometry

The wild lettuce species L. serriola, L. saligna, and L. virosa are important genitors in lettuce (L. sativa) breeding. Identifying these wild species can be problematic because in some cases they look very similar. Flow cytometry was tested for its reliability and general applicability as a tool to distinguish them. Three series of tests were conducted: (1) Tests with three accessions of L. sativa and one accession of each of the wild species, repeated three times throughout the year. In each repeat, the mean relative DNA amount of L. serriola was significantly higher than that of L. saligna, but significantly lower than that of L. virosa. The mean relative DNA amount of L. sativa did not differ from that of L. serriola.(2) Tests with each wild species represented by 10 accessions. Significant differences between the accessions within each species demonstrated the presence of intraspecific variation. Notwithstanding this intraspecific variation, the relative DNA amounts of all accessions of L. serriola were significantly higher than that of all L. saligna accessions, and significantly lower than that of all L. virosa accessions. Therefore, all accessions could be assigned to the appropriate species on the basis of their DNA amounts. (3) Tests with single plants from 10 accessions of each of the wild species. These test revealed that individual plants of L. serriola, L. saligna, and L. virosa can be reliably identified with flow cytometry, when aL. serriola sample of established identity is used as internal reference. This revised version was published online in July 2006 with corrections to the Cover Date.     

Molecular markers in Brassica oilseed breeding: current status and future possibilities

As PCR techniques have developed over the last 15 years, a wealth of new DNA marker technologies have arisen which have enabled the generation of high‐density molecular maps for all the major Brassica crop species. Molecular markers have also been heavily used in analyses of genetic diversity in Brassica crops. The majority of the work utilizing molecular markers in Brassica oilseed breeding has to date been based on genetic mapping using various DNA marker systems in segregating populations generated for specific investigations of particular traits of interest. For numerous qualitative traits, traditional mapping approaches have led to the development of marker‐assisted selection strategies in oilseed Brassica breeding, and in some cases to map‐based cloning of the responsible genes. For quantitative traits, however, it has become apparent that traditional mapping of quantitative trait loci (QTL) is often not sufficient to develop effective markers for trait introgression or for identification of the genes responsible. In this case, allele‐trait association studies in non‐structured genetic populations represent an interesting new approach, provided the degree of gametic phase disequilibrium between the QTL and the marker loci is sufficient. Because Brassica species represent the closest crop plant relatives to the model plant Arabidopsis thaliana, significant progress will be achieved in the coming years through integration of candidate gene approaches in crop brassicas, using the detailed information now available for the Arabidopsis genome. Integration of information from the model plant with the increasing supply of data from physical mapping and sequencing of the diploid Brassica genomes will undoubtedly give great insight into the genetics underlying both simple and complex traits in oilseed rape. This review describes the current use of available genetic marker technologies in oilseed rape breeding and provides an outlook for use of new technologies, including single‐nucleotide polymorphism markers, candidate gene approaches and allele‐trait association studies.     

Modelling concept of lettuce breeding for nutrient efficiency

Modern lettuce cultivars are bred for use under high levels of input of water and nutrients, and therefore less adapted to low-input or organic conditions in which nitrate availability varies over time and within the soil profile. To create robust cultivars it is necessary to assess which traits contribute to optimal resource capture and maximum resource use efficiency. We therefore revisited earlier published results on root growth, resource capture and resource use efficiency of lettuce exposed to localized drought and nitrate shortage in a pot experiment. Root growth in a soil profile with localized resource shortage depended on the resource that was in short supply. We conceptualized a model describing nitrogen uptake and use efficiency. We also investigated the genetic variation among 148 cultivars in resource capture over time and soil depth and in resource use efficiency in four (two locations × two planting dates) field experiments. Cultivars proved to be highly diverse in their ability to capture and use resources. This ability, however, was strongly affected by other sources of variance, stressing the need for an eco-physiological model capable of reducing the residual variance and improving the expression and evaluation of cultivar differences in relation to both resource capture and use efficiency in lettuce. We showed that genetic variation was best expressed under limiting conditions. To improve the conceptualized model further we identified issues requiring further analysis, e.g., the physiological reasons why certain cultivars are capable of quickly responding to changes in the environment to maintain optimal resource capture.     

早熟棉花优异种质选育

棉花 (包括野生棉 )中含有许多可利用的优异性状 ,其中大部分未被应用 ,而在早熟棉育种中则更少。主要是缺乏具有优异性状的早熟种质。选育具有不同优异性状的早熟棉种质材料具有重要意义。1　材料与方法材料为石家庄市农科院棉花育种室的中熟材料和从中国农科院棉花所、中国科学院遗传所、河北省邯郸市农科所等单位引进的中熟及早熟材料。根据目标性状遗传规律 ,选择含有目标性状的材料与常规品种杂交 ,并适度回交、自交 ,促进目标性状纯和稳定 ,结合南繁加代加快育种进程。逐年进行抗病性鉴定和纤维品质测试。2　结果与分析选育了具有抗病…     

Agronomical and quality traits of runner bean germplasm and implications for breeding

White runner bean landraces are greatly appreciated in the North highlands of Spain due to their excellent culinary seed quality. Runner bean cultivars are grown like pole beans. Diversity within a runner bean collection of 31 accessions from the Iberian Peninsula (Spain and Portugal) was examined using morphological, agronomical and seed quality traits. Landraces showed significant differences for most of the agronomical and seed quality traits studied except for seeds per pod, water absorption, seed coat tenderness and floury texture. Runner bean landraces showed sufficient variability to select inbred lines for future breeding. Genotype × environment interaction was significant for days to first flowering, days to first dry pod, seeds per pod and seed length. The majority of physical and nutritional seed quality traits studied which are important to determine the commercial value of a variety were not subject to environmental influences. Different selection pressures affecting to the runner bean genetic material could have occurred in several regions of the Iberian Peninsula. Extra-large and high yielding runner bean germplasm was identified and represents a valuable source of genetic diversity that has potential for development of improved cultivars to be chosen for commercialisation. This revised version was published online in July 2006 with corrections to the Cover Date.     

我国农作物育种科研面临的机遇与挑战

分析了我国农作物育种科研发展现状与机遇。对比国际种业育种技术发展现状,针对我国种业研发存在的问题,从政策扶持、科技支撑和知识产权3个方面提出了相关建议及实施路径。     

Research on the inheritance of seed dormancy in lettuce (Lactuca sativa L.) and selection for non-dormancy

Summary Inheritance of dormancy and the results of selection of non-dormant genotypes in segregating populations of lettuce were investigated. Diallel crosses were therefore carried out between two dormant (DOR) and two non-dormant (NDOR) cultivars. F₁, F₂ and F₃ populations were analysed.Environmental variation for dormancy usually was large. The mean germination time (GT) of F₁ seeds from the NDOR % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaciaacaqabeaadaqaaqaaaKaaafaafaqabeGaba% aajqgaa+FaaiaadIhaaeaacaWG4baaaaaa!3B90!\[\begin{array}{*{20}c}x \\x \\\end{array}\]DOR crosses was often intermediate to the GT of the NDOR and DOR parent. The mean GT of F₁ seeds from DOR % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaciaacaqabeaadaqaaqaaaKaaafaafaqabeGaba% aajqgaa+FaaiaadIhaaeaacaWG4baaaaaa!3B90!\[\begin{array}{*{20}c}x \\x \\\end{array}\]DOR crosses equalled the mean GT of the parents; the same applies for the NDOR % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaciaacaqabeaadaqaaqaaaKaaafaafaqabeGaba% aajqgaa+FaaiaadIhaaeaacaWG4baaaaaa!3B90!\[\begin{array}{*{20}c}x \\x \\\end{array}\]NDOR crosses. No differences between reciprocals were observed and neither were such differences found for F₂ populations. F₂ populations from DOR % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaciaacaqabeaadaqaaqaaaKaaafaafaqabeGaba% aajqgaa+FaaiaadIhaaeaacaWG4baaaaaa!3B90!\[\begin{array}{*{20}c}x \\x \\\end{array}\]DOR crosses showed no significant segregation of rapidly germinating seeds and in F₂ populations from NDOR % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaciaacaqabeaadaqaaqaaaKaaafaafaqabeGaba% aajqgaa+FaaiaadIhaaeaacaWG4baaaaaa!3B90!\[\begin{array}{*{20}c}x \\x \\\end{array}\]DOR crosses no accumulation of genes for long GT occurred. In F₂ populations from NDOR % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaciaacaqabeaadaqaaqaaaKaaafaafaqabeGaba% aajqgaa+FaaiaadIhaaeaacaWG4baaaaaa!3B90!\[\begin{array}{*{20}c}x \\x \\\end{array}\]DOR crosses usually 40–60% of the seeds germinated as rapidly as the seeds of the NDOR parents. Only one gene (D) could be responsible for the difference in dormancy behaviour of the DOR and NDOR cultivars. The behaviour of the F₃ lines from various NDOR % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaciaacaqabeaadaqaaqaaaKaaafaafaqabeGaba% aajqgaa+FaaiaadIhaaeaacaWG4baaaaaa!3B90!\[\begin{array}{*{20}c}x \\x \\\end{array}\]DOR crosses supports this hypothesis. A regression of F₃ means on the value of F₂ seeds for GT of various NDOR % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaciaacaqabeaadaqaaqaaaKaaafaafaqabeGaba% aajqgaa+FaaiaadIhaaeaacaWG4baaaaaa!3B90!\[\begin{array}{*{20}c}x \\x \\\end{array}\]DOR crosses showed that h²-narrow usually was rather high for most crosses implying that selection for non-dormancy can be carried out in F₂ populations.     

Utilization of exotic germplasm in Nordic barley breeding and its consequences for adaptation

Summary Utilization of exotic germplasm is one way to broaden genetic variation in breeding populations. This approach has recently been adopted in Sweden and Finland, where experimental barley populations has been established for research and pre-breeding purposes. The aim of the project is threefold: (1) to increase overall genetic diversity of Nordic barley breeding material; (2) to develop breeding material which possesses a high level of resistance for various barley diseases; and (3) to study effects of exotic germplasm on adaptation and agronomic performance. Both the Finnish and the Swedish barley populations include the same exotic material i.e. unadapted landraces from different parts of Asia and wild barley (Hordeum vulgare ssp. spontaneum) accessions. Locally adapted high-yielding barley lines were included in the populations. The establishment of these populations involved six crossing generations in order to promote recombination and enhance the break-up of linkage blocks. The paper discusses the third aim of the project. Studies on agronomic performance and adaptation showed that (1) agronomically valuable genotypes can be constructed through recombination using exotic germplasm for Nordic conditions, (2) that incorporation of exotic material is most successful when made in a local genetic base and (3) that exotic germplasm has an effect on adaptation.     

Analysis of the differences in growth between five lettuce cultivars marking the development in lettuce breeding for winter production

Summary Since 1950 growth of lettuce for winter production has been improved considerably by breeding. It has been investigated whether this improvement must be attributed to a more rapid leaf production, to larger leaves or to both. To this end the differences in growth between the cultivars Meikoningin. Proeftuin's Blackpool, Rapide, Deci-Minor and Valentine were analysed at a range of temperatures (10, 14, 17 and 20°C) under natural light conditions in autumn. The last four cultivars represent successive improvements in growth of lettuce for winter production.From the experiments it can be concluded that the improvement in growth of lettuce for winter production was initially brought about through increasing the rate of leaf production and there-after through increasing leaf size. At the same time the heat requirement for optimal growth has become higher.     

Environment of selection and type of germplasm in barley breeding for low-yielding conditions

Summary Thee groups consisting of 332, 243 and 280 barley breeding lines (entries) of known selection history were evaluated in 10, 9 and 8 environments, respectively, to determine the relationship between grain yield in low yielding (LYE) or high yielding (HYE) environment, and selection history and type of germplasm. One cycle of selection in LYE produced on average five times more entries outyielding the best check in LYE than selection in HYE. A retrospective analysis indicated that the highest yielding lines in LYE were lower yielding (15%–28%) in HYE when compared with the best check, and by 20% and 38% compared with the best entries in HYE. In contrast, the highest yielding lines in HYE were lower yielding (4%–33%) in LYE when compared with the best check, and by 33% and 40% when compared with the best entries in LYE. The highest yielding lines in LYE did not differ consistently from the highest yielding lines in HYE for a number of morphological and developmental traits including days to heading. This suggests there are many paths to high yield in LYE and that analytical breeding based on individual traits may not be appropriate for variable environments. Only 0.07% of the highest yielding entries in LYE was selected for high yield in HYE conditions confirming previous results indicating that selection for high yield in HYE is an inefficient strategy for improving yield in low yielding conditions. This frequency is 28 times lower than the frequency of high yielding entries in LYE selected from landraces or crosses with landraces in low yielding conditions. The results imply that the most cost-effective strategy for barley breeding in low yielding conditions is to select repeatedly in low yielding conditions and to include adapted germplasm (landraces) in the breeding material.     

Pigeonpea breeding in eastern and southern Africa: challenges and opportunities

Pigeonpea (Cajanus cajan [L.] Millspaugh) is an important multipurpose grain legume crop primarily grown in tropical and subtropical areas of Asia, Africa and Latin America. In Africa, the crop is grown for several purposes including food security, income generation, livestock feed and in agroforestry. Production in Eastern and Southern Africa (ESA) is however faced with many challenges including limited use of high‐yielding cultivars, diseases and pests, drought, under‐investment in research and lack of scientific expertise. The aim of this review is to highlight the challenges facing pigeonpea breeding research in ESA and the existing opportunities for improving the overall pigeonpea subsector in the region. We discuss the potential of the recently available pigeonpea genomic resources for accelerated molecular breeding, the prospects for conventional breeding and commercial hybrid pigeonpea, and the relevant seed policies, among others, which are viewed as opportunities to enhance pigeonpea productivity.     

Participatory plant breeding research: Opportunities and challenges for the international crop improvement system

This paper describes the current state of international plant breeding research and explains why the centralized global approach to germplasm improvement that was so successful in the past is today being transformed by the incorporation of decentralized local breeding methods designed to better incorporate the perspective of end users into the varietal development process. It describes international breeding efforts for major crops and identifies factors that have contributed to the success of the international breeding system; discusses shortcomings of the global approach to plant breeding and explains why future successes will depend critically on researchers' ability to incorporate the knowledge and preferences of technology users; reviews a number of farmer participatory research methods that are currently being tested by plant breeding programs throughout the developing world; describes synergies that can potentially be achieved by linking centralized global and decentralized local breeding models; and discusses technical, economic, and institutional challenges that will have to be overcome to integrate end user-based participatory approaches into the international plant breeding system. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genome-wide genetic dissection of germplasm resources and implications for breeding by design in soybean

“Breeding by Design” as a concept described by Peleman and van der Voort aims to bring together superior alleles for all genes of agronomic importance from potential genetic resources. This might be achievable through high-resolution allele detection based on precise QTL (quantitative trait locus/loci) mapping of potential parental resources. The present paper reviews the works at the Chinese National Center for Soybean Improvement (NCSI) on exploration of QTL and their superior alleles of agronomic traits for genetic dissection of germplasm resources in soybeans towards practicing “Breeding by Design”. Among the major germplasm resources, i.e. released commercial cultivar (RC), farmers’ landrace (LR) and annual wild soybean accession (WS), the RC was recognized as the primary potential adapted parental sources, with a great number of new alleles (45.9%) having emerged and accumulated during the 90 years’ scientific breeding processes. A mapping strategy, i.e. a full model procedure (including additive (A), epistasis (AA), A × environment (E) and AA × E effects), scanning with QTLNetwork2.0 and followed by verification with other procedures, was suggested and used for the experimental data when the underlying genetic model was usually unknown. In total, 110 data sets of 81 agronomically important traits were analyzed for their QTL, with 14.5% of the data sets showing major QTL (contribution rate more than 10.0% for each QTL), 55.5% showing a few major QTL but more small QTL, and 30.0% having only small QTL. In addition to the detected QTL, the collective unmapped minor QTL sometimes accounted for more than 50% of the genetic variation in a number of traits. Integrated with linkage mapping, association mappings were conducted on germplasm populations and validated to be able to provide complete information on multiple QTL and their multiple alleles. Accordingly, the QTL and their alleles of agronomic traits for large samples of RC, LR and WS were identified and then the QTL-allele matrices were established. Based on which the parental materials can be chosen for complementary recombination among loci and alleles to make the crossing plans genetically optimized. This approach has provided a way towards breeding by design, but the accuracy will depend on the precision of the loci and allele matrices.     

Developing standardized methods for breeding preharvest sprouting resistant wheat, challenges and successes in Canadian wheat

Preharvest sprouting (PHS) in spring wheat (Triticum aestivum L.) and durum wheat (T. turgidum L. var durum) causes significant economic losses due to a reduction in grain yield, grain functionality and viability of seed for planting. Average annual estimated losses in Canada are about $100 million. Genetic resistance to PHS reduces these losses. Development of PHS resistant cultivars is complicated by the effects of factors under genetic control, such as spike morphology, seed dormancy, environment, and kernel diseases. Resistance to PHS has been a breeding priority since the late 1960s. Development of RL4137, which is the primary source of PHS resistance in the Canada Western Red Spring market class, has led to cultivar improvements. A white-seeded derivative of RL4137 is the primary source of PHS in the Canada Prairie Spring White and Canada Western Hard White Spring wheat market classes. Procedures to select for PHS resistance vary among breeding programs, market classes and by degree of inbreeding. Methods include artificial sprouting of intact spikes, germination tests, natural weathering in field trials, artificial weathering trials, and indirect assessment of sprouting by measuring Hagberg falling number. Although many genetic loci have been attributed to preharvest sprouting resistance, application of molecular markers is currently limited due to the complex inheritance of the trait. In Canada, cultivars are characterized for their relative level of PHS resistance and the information is made available to producers.     

Aromatic- and di-carboxylates inhibit wound-induced phenolic accumulation in excised lettuce (Lactuca sativa L.) leaf tissue

Excision of de-bladed 5-mm mid-rib segments from Romaine lettuce leaf tissue induced a five-fold rise in phenolic concentration when held at 10 °C for 48 h. Immersion in aqueous solutions of various di-carboxylates and aromatic carboxylates for 1 h reduced this wound-induced increase. The decrease was linear for di-carboxylates with increasing length from 3 to 14 carbons, with the phenolic concentration becoming less than the control for compounds with more than 6 carbons. Aromatic carboxylates with a hydroxyl at the 2 position and another at an even position produced an average reduction of 46%, while aromatic carboxylates with no hydroxyl groups, groups at odd positions, or adjacent groups produced an average 12% reduction. The decrease in wound-induced phenolic accumulation produced by 10 mM solutions of aromatic- and di-carboxylates was linearly correlated (R² = 0.91) with the rate of carbon dioxide production, indicating possible tissue damage. This possibility was supported by the fact that most effective concentrations were highly correlated with increased ion leakage, another measure of tissue damage. While delaying the application of inhibitors of wound signal synthesis (e.g., n-alcohols) decreases their effectiveness, delaying the 1 h immersion in aromatic and di-carboxylate solutions for 4 h did not significantly reduce their effectiveness. Like mono-carboxylates, aromatic and di-carboxylates do not appear to be interfering with the synthesis or propagation of a wound signal, but appear to be inhibiting phenolic synthesis and/or accumulation at some subsequent step in the wound response.     

Wheat improvement in India: present status,emerging challenges and future prospects

India is the second largest producer of wheat in the world, with production hovering around 68–75 million tons for past few years. The latest estimated demand for wheat production for the year 2020 is approximately 87.5 million tons, or about 13 million tons more than the record production of 75 million tons harvested in crop season 1999–2000. Since 2000, India has struggled to match that record production figure and thus faces a critical challenge in maintaining food security in the face of its growing population. The current major challenges facing future wheat production in India are increasing heat stress; dwindling water supplies for irrigation; a growing threat of new virulence of diseases such as wheat rusts (yellow, brown, and black) and leaf blight; continuous adoption of rice-wheat systems on around 11 million hectares; changes in urbanization patterns, and demand for better quality wheat. In addition, the threat posed by the new stem rust race Ug99 can not be underestimated. The wide gap (around 2.5 t/ha) between the potential and harvested yield in the eastern Gangetic Plains also cries out for solutions. Addressing issues related to different stresses will require harnessing genes discovered in landraces and wild relatives following conventional as well as non-conventional approaches. For effective technology delivery in areas that suffer from poor linkages with farmers, participatory research needs to be strengthened. The future germplasm requirements from a dependable collaborator such as CIMMYT are largely being dictated by the above factors.