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Plants developing into the flowering stage undergo major physiological changes. Because flowers are reproductive tissues and resource sinks, strategies to defend them may differ from those for leaves. Thus, this study investigates the defences of flowering plants by assessing processes that sustain resistance (constitutive and induced) and tolerance to attack. We exposed the annual plant Brassica nigra to three distinct floral attackers (caterpillar, aphid and bacterial pathogen) and measured whole-plant responses at 4, 8 and 12 days after the attack. We simultaneously analysed profiles of primary and secondary metabolites in leaves and inflorescences and measured dry biomass of roots, leaves and inflorescences as proxies of resource allocation and regrowth. Regardless of treatments, inflorescences contained 1.2 to 4 times higher concentrations of primary metabolites than leaves, and up to 7 times higher concentrations of glucosinolates, which highlights the plant's high investment of resources into inflorescences. No induction of glucosinolates was detected in inflorescences, but the attack transiently affected the total concentration of soluble sugars in both leaves and inflorescences. We conclude that B. nigra evolved high constitutive rather than inducible resistance to protect their flowers; plants additionally compensated for damage by attackers via the regrowth of reproductive parts. This strategy may be typical of annual plants.

Drought is a major crop production constraint worldwide. Some legume crops are known for their ability to resist water deficit stress. This study evaluated the responses of bambara groundnut (Vigna subterranea (L.) Verdc) and groundnut (Arachis hypogaea (L.) to soil water deficit stress. The experiment was set as a split-plot randomized complete block design. Three bambara groundnut landraces: viz DodR, NALBAM 4 and S19-3, and one groundnut variety, MNANJE, were assigned to subplots with three water regimes assigned to main plots (regime one: irrigated throughout the growing period, regime two: water deficit stress was imposed at the start of flowering to the end of first flush flowering, regime three: water was withheld during the pod development). Water deficit stress increased proline content by 123% in stressed plots. The highest (174%) and lowest (89%) proline increases were evident in the genotypes MNANJE and NALBAM 4, respectively. Water deficit decreased stomatal conductance, transpiration rate and photosynthetic rate, with MNANJE and S19-3 showing the smallest percentage decrease in most of the traits. This suggests that the two genotypes are drought resistant. The variations observed among landraces could be exploited to breed resilient varieties for cultivation in drought-prone areas, ultimately improving food security.

Populations of the same plant species living in different locations but flowering at different times may vary in pollinator availability and floral traits. However, the spatial and temporal links between floral traits and pollination are rarely included in single studies. In this study, three populations of an alpine lousewort, Pedicularis rhinanthoides Schrenk subsp. tibetica (Bonati) Tsoong, were surveyed to detect the variations in floral traits and pollinator activity. We hypothesized that floral divergence was spatio-temporally correlated with pollen limitation (PL) in relation to pollinators. Sampled plants from each population were divided into three groups, according to flowering stage: early, peak, and late. Pollen-supplementation experiments and investigations into pollinators, reproductive success, and floral traits were conducted on the plants from the different flowering stages and across the populations. Our results showed that the extent of PL varies across populations and among flowering stages. Populations in which more pollinators were recorded displayed a lower extent of PL. Furthermore, the temporal differences in PL showed a similar pattern for the three populations; the plants from the peak flowering stage suffered slighter PL than those from the other two stages. Nevertheless, some of the floral traits displayed similar spatial and temporal patterns to the PL, while the others only varied among the populations spatially. The results indicated that the performance of floral traits in a particular spatial–temporal situation shows they are well adapted to the corresponding pollination environment, which might help plants to optimize their reproductive fitness under different abiotic factors.

Aphid is one of the main insect pests of wheat in the flowering stage, so timely and effective control of wheat aphids plays an important role in ensuring wheat yield. The crop protection Unmanned Aerial Vehicle (UAV) is widely used in the control of wheat pests and diseases nowadays. In order to screen out the suitable operation parameters of the crop protection UAV to control the wheat aphids, this study conducted wheat aphid distribution investigation tests and droplet distribution tests. With the P20 electric four-rotor crop protection UAV (Guangzhou Jifei Technology Co., Ltd., Guangzhou, China) as the test equipment, four levels of flight speed (FS: 3, 4, 5, 6 m/s) and three levels of flight height (FH: 1.5, 2, 2.5 m) were combined as operation parameters, tests were carried out to compare the density and uniformity of droplet coverage, and the wheat aphid control tests were carried out by using the optimized operation parameters. The results of the wheat aphid distribution investigation test showed that aphids mainly distributed in the lower layer of the wheat plant canopy, accounting for more than 90.61%. The results of the droplet distribution test showed that with the increase in FS and FH, the coverage density and the droplet distribution uniformity in the upper and lower layers of wheat showed a downward trend under the condition of considering the boundary overlap of spraying width (SW) in multi-routes. Through the comparison of operation efficiency and droplet distribution quality, two combinations of parameters A1 (FS: 3 m/s, FH: 1.5 m) and B1 (FS: 4 m/s, FH: 1.5 m) were selected for the aphid control effect test. The results of the control test showed that the average control effect of A1 (92.05%) on aphids was 10.3% higher than that of B1 (81.75%) 7 days after pesticide application, which indicated that improving the droplet distribution uniformity in the lower layer of wheat could significantly improve the control effect of aphids. This study result could provide reference for the same type of crop protection UAV to control the same type of wheat diseases and insect pests in the same growing stage.

Due to climate change, more temperature extremes are expected in the future, potentially endangering agricultural production. Chickpea (Cicer arietinum L.) is an important cool-season food legume grown worldwide; however, cold and heat episodes are major threats in chickpea production that cause considerable yield losses especially at the flowering stage. The aim of this study was to evaluate the physiological performance of contrasting chickpea genotypes during the flowering phase under cold and heat. Four chickpea genotypes (Desi, Eldorado, Acc#2 and Acc#7) with different temperature susceptibilities were treated for 3 days under cold (9/4 °C) and heat (38/33 °C). The results showed that cold stress reduced the maximum quantum efficiency of photosystem II (Fv/Fm) by 5%, net photosynthetic rate (PN) by 74%, and chlorophyll a+b content by 31% on average in all tested genotypes. Up to a 9-fold increase in the amount of starch was found in the leaves of plants under cold stress, indicating that carbohydrates strongly accumulated in chickpeas under cold stress. This helps to maintain the vegetative and generative organs and enable fast recovery. Under heat stress, chickpeas maintained Fv/Fm and PN, although chlorophyll a+b content decreased by 39% on average. Carbohydrates did not accumulate under heat in chickpeas; thereby, a reduction in biomass and reproductive organs took place. Genetic variation in response to cold and heat stress was detected among the tested flowering chickpea genotypes. Desi and Acc#2 were cold-sensitive candidates, and Eldorado was a cold-tolerant candidate, whereas Acc#7 and Acc#2 were heat-sensitive candidates, while Desi and Eldorado were heat-tolerant candidates. This study provides important knowledge on the physiological response of flowering chickpeas under cold and heat stress. This will benefit the identification of stress-tolerant chickpea genotypes to ensure high yields in the future climate.

Heracleum persicum, commonly named Persian hogweed, is a principal native medicinal plant in Iran. Collecting H. persicum at the most appropriate growing stage is the key factor to achieve the high phytochemical quality to meet consumer's needs. In the present experiment, the aerial parts of this plant were harvested at up to six different developmental stages during the growing season to determine the phytochemical profiles. Our results indicated that the highest essential oil content was obtained in the mid‐mature seed stage (3.5%). The most elevated extract content was recorded in the floral budding stage (10.4%). In the vegetative stage, limonene (18.1%), in floral budding stage, caryophyllene (14.1%), anethole (14.6%), and β‐bisabolene (12.7%), in the full flowering stage, myristicin (15.0%), and hexyl butyrate (9.1%), in the early development of seeds stage, hexyl butyrate (32.1%), and octyl acetate (11.7%), in the mid‐mature seeds stage hexyl butyrate (38.8%), octyl acetate (14.5%), in the late‐mature/ripe seeds stage, hexyl butyrate (23.6%), and octyl acetate (10.5%) are recorded as the main components. The highest phenolic acids content was obtained in the floral budding stage (287.40 mg/g dried extract). The analysis of phenolic acids demonstrated cinnamic acid (8.0–225.3 mg/g extract), p‐coumaric acid (1.7–39.2 mg/g extract), p‐hydroxybenzoic acid (0.8–16.8 mg/g extract), and ferulic acid (2.4–15.8 mg/g extract) as the main phenolic acids. Cinnamic acid was found as the major phenolic compound in the vegetative stage following by floral budding, the full flowering stage, the early development of seeds, and late‐mature/ripe seeds stages. P‐coumaric acid was the most abundant phenolic compounds in the mid‐mature seeds stage. In this regard, the harvest time of H. persicum aerial parts can be selected to achieve the highest secondary metabolites of interest. The results of this study can be used as a guideline for grower to obtain the highest possible amount of desirable metabolites, beneficial in both food and pharmaceutical industries as well as their undeniable economical benefits.

Background This study was aimed at investigating the possible anti-inflammatory and cytotoxic effects of extracts from the flowering stage of C. argentea. This growth stage was chosen because of its high polyphenolic content and high antioxidant capacity. Methods Anti-inflammatory potential of the aqueous, acetone and methanol extracts of C. argentea was evaluated through the inhibition of nitric oxide production (LPS-induced) on stimulated macrophages (RAW 264.7), while MTT assay was used to assess cell viability with Silymarin as standard. Cytotoxicity of the plant extracts was evaluated on murine preadipocyte cell line (3 T3-L1) using the image-based method of two DNA-binding dyes; Hoechst 33342 and propidium iodide (PI) with melphalan as standard. Results Acetone extract exhibited moderate, dose-dependent anti-inflammatory activity with no significant toxicity to activated macrophages, however the aqueous and methanol extracts were unable to inhibit nitric oxide production at both trials. MTT assay and the toxicity assay revealed that the flowering stage extracts of C. argentea were not toxic to the RAW 264.7 macrophages and 3 T3-L1 cells at all the tested concentrations (0, 2, 50, 100 and 200 μg/mL). Conclusions These findings corroborate the traditional use of C. argentea for painful inflammatory conditions and encourage its possible use as lead for the development of novel, non-toxic, anti-inflammatory agents.

Current agricultural methodologies are vulnerable to erratic climate and are dependent on cost-intensive fertilization to ensure high yields. Sustainable practices should be pursued to ensure food security. Phaseolus vulgaris L. is one of the most produced legumes worldwide and may be an alternative to reduce the environmental impact of meat production as a reliable source of high-quality protein. Plant growth-promoting rhizobacteria (PGPR) are emerging as a sustainable option to increase agricultural production. To understand the dynamics between plants and microorganisms, the culturable microbiota of bean roots was isolated and identified at distinct stages of plant development (early and late vegetative growth, flowering, and pod) and root compartments (rhizoplane, endosphere, and nodules). Diversity and abundance of bacteria associated with root compartments differed throughout the plant life cycle. Bacterial plant growth promotion (PGP) and protection abilities (indole-3-acetic acid production, siderophore synthesis, and antifungal activity) were assessed and associated with plant phenology, demonstrating that among the bacteria associated with plant roots, several strains had an active role in the response to plant biological needs at each stage. Several strains stood out for their ability to display one or more PGP traits, being excellent candidates for efficient stage-specific biostimulants for application in precision agriculture.

The color of bracts generally turns yellow or black from green during cereal grain development. However, the impact of these phenotypic changes on photosynthetic physiology during black bract formation remains unclear. Two oat cultivars (Avena sativa L.), ‘Triple Crown’ and ‘Qinghai 444’, with yellow and black bracts, respectively, were found to both have green bracts at the heading stage, but started to turn black at the flowering stage and become blackened at the milk stage for ‘Qinghai 444’. Their photosynthetic characteristics were analyzed and compared, and the key genes, proteins and regulatory pathways affecting photosynthetic physiology were determined in ‘Triple Crown’ and ‘Qinghai 444’ bracts. The results show that the actual PSII photochemical efficiency and PSII electron transfer rate of ‘Qinghai 444’ bracts had no significant changes at the heading and milk stages but decreased significantly (p &lt, 0.05) at the flowering stage compared with ‘Triple Crown’. The chlorophyll content decreased, the LHCII involved in the assembly of supercomplexes in the thylakoid membrane was inhibited, and the expression of Lhcb1 and Lhcb5 was downregulated at the flowering stage. During this critical stage, the expression of Bh4 and C4H was upregulated, and the biosynthetic pathway of p-coumaric acid using tyrosine and phenylalanine as precursors was also enhanced. Moreover, the key upregulated genes (CHS, CHI and F3H) of anthocyanin biosynthesis might complement the impaired PSII activity until recovered at the milk stage. These findings provide a new insight into how photosynthesis alters during the process of oat bract color transition to black.

High-temperature stress can cause serious abiotic damage that limits the yield and quality of rice. Heat tolerance (HT) during the flowering stage of rice is a key trait that can guarantee a high and stable yield under heat stress. HT is a complex trait that is regulated by multiple quantitative trait loci (QTLs); however, few underlying genes have been fine mapped and cloned. In this study, the F2:3 population derived from a cross between Huanghuazhan (HHZ), a heat-tolerant cultivar, and 9311, a heat-sensitive variety, was used to map HT QTLs during the flowering stage in rice. A new major QTL, qHTT8, controlling HT was identified on chromosome 8 using the bulked-segregant analysis (BSA)-seq method. The QTL qHTT8 was mapped into the 3,555,000–4,520,000 bp, which had a size of 0.965 Mb. The candidate region of qHTT8 on chromosome 8 contained 65 predicted genes, and 10 putative predicted genes were found to be associated with abiotic stress tolerance. Furthermore, qRT-PCR was performed to analyze the differential expression of these 10 genes between HHZ and 9311 under high temperature conditions. LOC_Os08g07010 and LOC_Os08g07440 were highly induced in HHZ compared with 9311 under heat stress. Orthologous genes of LOC_Os08g07010 and LOC_Os08g07440 in plants played a role in abiotic stress, suggesting that they may be the candidate genes of qHTT8. Generally, the results of this study will prove useful for future efforts to clone qHTT8 and breed heat-tolerant varieties of rice using marker-assisted selection.

Drought is one of the most critical environmental factors constraining maize production. When it occurs at the flowering stage, serious yield losses are caused, and often, the damage is irretrievable. In this study, anthesis to silk interval (ASI), plant height (PH), and ear biomass at the silking date (EBM) of 279 inbred lines were studied under both water-stress (WS) and well-water (WW) field conditions, for three consecutive years. Averagely, ASI was extended by 25.96%, EBM was decreased by 17.54%, and the PH was reduced by 12.47% under drought stress. Genome-wide association studies were carried out using phenotypic values under WS, WW, and drought-tolerance index (WS-WW or WS/WW) and applying a mixed linear model that controls both population structure and relative kinship. In total, 71, 159, and 21 SNPs, located in 32, 59, and 12 genes, were significantly (P < 10−5) associated with ASI, EBM, and PH, respectively. Only a few overlapped candidate genes were found to be associated with the same drought-related traits under different environments, for example, ARABIDILLO 1, glycoprotein, Tic22-like, and zinc-finger family protein for ASI; 26S proteasome non-ATPase and pyridoxal phosphate transferase for EBM; 11-ß-hydroxysteroid dehydrogenase, uncharacterised, Leu-rich repeat protein kinase, and SF16 protein for PH. Furthermore, most candidate genes were revealed to be drought-responsive in an association panel. Meanwhile, the favourable alleles/key variations were identified with a haplotype analysis. These candidate genes and their key variations provide insight into the genetic basis of drought tolerance, especially for the female inflorescence, and will facilitate drought-tolerant maize breeding.

Heracleum persicum, commonly named Persian hogweed, is a principal native medicinal plant in Iran. Collecting H. persicum at the most appropriate growing stage is the key factor to achieve the high phytochemical quality to meet consumer's needs. In the present experiment, the aerial parts of this plant were harvested at up to six different developmental stages during the growing season to determine the phytochemical profiles. Our results indicated that the highest essential oil content was obtained in the mid‐mature seed stage (3.5%). The most elevated extract content was recorded in the floral budding stage (10.4%). In the vegetative stage, limonene (18.1%), in floral budding stage, caryophyllene (14.1%), anethole (14.6%), and β‐bisabolene (12.7%), in the full flowering stage, myristicin (15.0%), and hexyl butyrate (9.1%), in the early development of seeds stage, hexyl butyrate (32.1%), and octyl acetate (11.7%), in the mid‐mature seeds stage hexyl butyrate (38.8%), octyl acetate (14.5%), in the late‐mature/ripe seeds stage, hexyl butyrate (23.6%), and octyl acetate (10.5%) are recorded as the main components. The highest phenolic acids content was obtained in the floral budding stage (287.40 mg/g dried extract). The analysis of phenolic acids demonstrated cinnamic acid (8.0–225.3 mg/g extract), p‐coumaric acid (1.7–39.2 mg/g extract), p‐hydroxybenzoic acid (0.8–16.8 mg/g extract), and ferulic acid (2.4–15.8 mg/g extract) as the main phenolic acids. Cinnamic acid was found as the major phenolic compound in the vegetative stage following by floral budding, the full flowering stage, the early development of seeds, and late‐mature/ripe seeds stages. P‐coumaric acid was the most abundant phenolic compounds in the mid‐mature seeds stage. In this regard, the harvest time of H. persicum aerial parts can be selected to achieve the highest secondary metabolites of interest. The results of this study can be used as a guideline for grower to obtain the highest possible amount of desirable metabolites, beneficial in both food and pharmaceutical industries as well as their undeniable economical benefits., The development stage has a significant impact on the content and composition of both essential oil and phenolic acid composition. The harvest time of H. persicum aerial parts can be selected to achieve the highest secondary metabolites of interest.

The response of compensatory growth is an important adaptive strategy for plants to grazing. However, most previous studies on compensatory growth of plants focused on the compensation of the biomass or the number of sexual reproductive offspring and neglected the compensatory growth of vegetative reproduction (VR). This is important not only for plant compensatory growth studies, but also for theoretical and practical studies of grassland production. The clonal tussock grass Hordeum brevisubulatum was selected as the research object. Four different clipping severities (unclipping and clipping stubble at heights of 15, 10, and 5 cm) at the jointing stage and flowering stage were implemented to study the effect of simulated grazing. To explore the effect of recovery growth time on plant growth after simulated grazing, three sampling times were used at different recovery times after simulated grazing (1, 3, and 7 weeks). We found that light and moderate grazing severity significantly increased the number of vegetative reproduction modules, the promotion of simulated grazing on the number of vegetative reproduction modules was higher in the jointing stage than the flowering stage, and the increase in simulated grazing severity decreased with prolonged recovery growth time. The number of tillers significantly decreased with the increase in simulated grazing in both the jointing and flowering stages at 1 week after damage, and the decreasing effect weakened with the prolonged recovery growth time. The bud number mainly showed over-compensation, the juvenile tiller number showed complete compensation, and the tiller number showed under-compensation at 1 and 3 weeks after recovery growth. The number of tillers showed complete compensation under different grazing severities in the jointing stage, while it showed under-compensation in the flowering stage at 7 weeks after recovery growth. Our results indicated that different grazing severities in the jointing stage could promote the output of tillers with matter production capacity from vegetative reproduction modules, as well as improve the capability of compensatory growth. Therefore, in plant production, there will be a sustainable development effect on the renewal and productivity of the H. brevisubulatum population, resulting in different grazing severities in the jointing stage.

The response of compensatory growth is an important adaptive strategy for plants to grazing. However, most previous studies on compensatory growth of plants focused on the compensation of the biomass or the number of sexual reproductive offspring and neglected the compensatory growth of vegetative reproduction (VR). This is important not only for plant compensatory growth studies, but also for theoretical and practical studies of grassland production. The clonal tussock grass Hordeum brevisubulatum was selected as the research object. Four different clipping severities (unclipping and clipping stubble at heights of 15, 10, and 5 cm) at the jointing stage and flowering stage were implemented to study the effect of simulated grazing. To explore the effect of recovery growth time on plant growth after simulated grazing, three sampling times were used at different recovery times after simulated grazing (1, 3, and 7 weeks). We found that light and moderate grazing severity significantly increased the number of vegetative reproduction modules, the promotion of simulated grazing on the number of vegetative reproduction modules was higher in the jointing stage than the flowering stage, and the increase in simulated grazing severity decreased with prolonged recovery growth time. The number of tillers significantly decreased with the increase in simulated grazing in both the jointing and flowering stages at 1 week after damage, and the decreasing effect weakened with the prolonged recovery growth time. The bud number mainly showed over-compensation, the juvenile tiller number showed complete compensation, and the tiller number showed under-compensation at 1 and 3 weeks after recovery growth. The number of tillers showed complete compensation under different grazing severities in the jointing stage, while it showed under-compensation in the flowering stage at 7 weeks after recovery growth. Our results indicated that different grazing severities in the jointing stage could promote the output of tillers with matter production capacity from vegetative reproduction modules, as well as improve the capability of compensatory growth. Therefore, in plant production, there will be a sustainable development effect on the renewal and productivity of the H. brevisubulatum population, resulting in different grazing severities in the jointing stage.

Background Reduction in rice yield caused by high temperature-induced spikelet sterility has been a serious concern in rice production. To date, several screening methods have been used, although their reproducibility is sometimes poor due to artifacts mainly caused by varietal differences in heading dates and panicle heights (i.e., the distance from the lamps). Methods We have developed a novel assay system for heat-induced spikelet sterility by using artificial rice paddies in phytotrons to conduct a highly reproducible assay throughout a year. Plants restricted to the main culm were treated under a series of heat conditions, and height uniformity of each plant was ensured by using height-adjustable pots. Results Results suggested that a 3-day heat treatment of 35 °C-day/29 °C-night cycles was the most suitable condition. Under the treatment, two distinct groups were identified among nine heat tolerant cultivars, with no varietal difference in panicle temperature, indicating that the system is capable of eliminating the varietal difference in panicle temperature. Conclusions It is concluded that the assay system would be a powerful tool for selecting heat tolerant varieties, as well as the analysis of genetic factors from various cultivars, eliminating potential artifacts. Electronic supplementary material The online version of this article (doi:10.1186/s13007-017-0185-3) contains supplementary material, which is available to authorized users.

Background: The leaves, roots and seeds of Lovage (Levisticum officinale Koch) being used as an herb, vegetable and spice. Objective: The aim of this study is evaluation of the changes of phytochemical compound in aerial parts of the Lovage plants at different developmental stages as well as antioxidant activity. Methods: The plants were harvested from Hezar Mountain. After drying, essential oils were extracted by steam distillation. To identify the essential components GC and GC-MS was used. Antioxidant activity of samples was examined by diphenylpicrylhydrazyl (DPPH) assay. Results: The average yield of essential oil was respectively, 2.3% and 3.1% and 1.5% respectively, in vegetative, Flowering and seed stage. The oil analysis results showed that 21 compounds were identified in the vegetative stage. β-phellandrene (10.7%) and α-Terpinyl acetate (% 38.9) and Curzerene (% 10.6) were the major compound. in the reproductive stage, 22 compounds were identified including β-phellandrene (20.3%) and α-Terpinyl acetate (% 20.4) and γ-Cadinene (12.1%). in the seed stage β-phellandrene (21.1%) and α-Terpinyl acetate (% 25.3) and Sabinene (10.2%) were the highest. Analysis of variance showed that the effect of harvesting time has significant effect on plant height, stem branch number and yield of oil. The Higher antioxidant power was observed respectively in the flowering stage (83%), vegetative stage (68%) and seed stage (60%). Conclusion: The phytochemical and antioxidant compounds in Levisticum officinale depend on the phenological stage.

BackgroundSalt stress, a major plant environmental stress, is a critical constraint for rice productivity. Dissecting the genetic loci controlling salt tolerance in rice for improving productivity, especially at the flowering stage, remains challenging. Here, we conducted a genome-wide association study (GWAS) of salt tolerance based on exome sequencing of the Thai rice accessions.ResultsPhotosynthetic parameters and cell membrane stability under salt stress at the flowering stage; and yield-related traits of 104 Thai rice (Oryza sativa L.) accessions belonging to the indica subspecies were evaluated. The rice accessions were subjected to exome sequencing, resulting in 112,565 single nucleotide polymorphisms (SNPs) called with a minor allele frequency of at least 5%. LD decay analysis of the panel indicates that the average LD for SNPs at 20 kb distance from each other was 0.34 (r2), which decayed to its half value (~ 0.17) at around 80 kb. By GWAS performed using mixed linear model, two hundred loci containing 448 SNPs on exons were identified based on the salt susceptibility index of the net photosynthetic rate at day 6 after salt stress; and the number of panicles, filled grains and unfilled grains per plant. One hundred and forty six genes, which accounted for 73% of the identified loci, co-localized with the previously reported salt quantitative trait loci (QTLs). The top four regions that contained a high number of significant SNPs were found on chromosome 8, 12, 1 and 2. While many are novel, their annotation is consistent with potential involvement in plant salt tolerance and in related agronomic traits. These significant SNPs greatly help narrow down the region within these QTLs where the likely underlying candidate genes can be identified.ConclusionsInsight into the contribution of potential genes controlling salt tolerance from this GWAS provides further understanding of salt tolerance mechanisms of rice at the flowering stage, which can help improve yield productivity under salinity via gene cloning and genomic selection.

Background Salt stress, a major plant environmental stress, is a critical constraint for rice productivity. Dissecting the genetic loci controlling salt tolerance in rice for improving productivity, especially at the flowering stage, remains challenging. Here, we conducted a genome-wide association study (GWAS) of salt tolerance based on exome sequencing of the Thai rice accessions. Results Photosynthetic parameters and cell membrane stability under salt stress at the flowering stage; and yield-related traits of 104 Thai rice (Oryza sativa L.) accessions belonging to the indica subspecies were evaluated. The rice accessions were subjected to exome sequencing, resulting in 112,565 single nucleotide polymorphisms (SNPs) called with a minor allele frequency of at least 5%. LD decay analysis of the panel indicates that the average LD for SNPs at 20 kb distance from each other was 0.34 (r2), which decayed to its half value (~ 0.17) at around 80 kb. By GWAS performed using mixed linear model, two hundred loci containing 448 SNPs on exons were identified based on the salt susceptibility index of the net photosynthetic rate at day 6 after salt stress; and the number of panicles, filled grains and unfilled grains per plant. One hundred and forty six genes, which accounted for 73% of the identified loci, co-localized with the previously reported salt quantitative trait loci (QTLs). The top four regions that contained a high number of significant SNPs were found on chromosome 8, 12, 1 and 2. While many are novel, their annotation is consistent with potential involvement in plant salt tolerance and in related agronomic traits. These significant SNPs greatly help narrow down the region within these QTLs where the likely underlying candidate genes can be identified. Conclusions Insight into the contribution of potential genes controlling salt tolerance from this GWAS provides further understanding of salt tolerance mechanisms of rice at the flowering stage, which can help improve yield productivity under salinity via gene cloning and genomic selection. Electronic supplementary material The online version of this article (10.1186/s12864-018-5317-2) contains supplementary material, which is available to authorized users.

BackgroundSalt stress, a major plant environmental stress, is a critical constraint for rice productivity. Dissecting the genetic loci controlling salt tolerance in rice for improving productivity, especially at the flowering stage, remains challenging. Here, we conducted a genome-wide association study (GWAS) of salt tolerance based on exome sequencing of the Thai rice accessions.ResultsPhotosynthetic parameters and cell membrane stability under salt stress at the flowering stage; and yield-related traits of 104 Thai rice (Oryza sativa L.) accessions belonging to the indica subspecies were evaluated. The rice accessions were subjected to exome sequencing, resulting in 112,565 single nucleotide polymorphisms (SNPs) called with a minor allele frequency of at least 5%. LD decay analysis of the panel indicates that the average LD for SNPs at 20 kb distance from each other was 0.34 (r2), which decayed to its half value (~ 0.17) at around 80 kb. By GWAS performed using mixed linear model, two hundred loci containing 448 SNPs on exons were identified based on the salt susceptibility index of the net photosynthetic rate at day 6 after salt stress; and the number of panicles, filled grains and unfilled grains per plant. One hundred and forty sixgenes, which accounted for 73% of the identified loci, co-localized with the previously reported salt quantitative trait loci (QTLs). The top four regions that contained a high number of significant SNPs were found on chromosome 8, 12, 1 and 2. While many are novel, their annotation is consistent with potential involvement in plant salt tolerance and in related agronomic traits. These significant SNPs greatly help narrow down the region within these QTLs where the likely underlying candidate genes can be identified.ConclusionsInsight into the contribution of potential genes controlling salt tolerance from this GWAS provides further understanding of salt tolerance mechanisms of rice at the flowering stage, which can help improve yield productivity under salinity via gene cloning and genomic selection.

Science & Technology Asia, 24, 4, 126-134

Создание новых, более продуктивных сортов зерновых культур часто связано с усилением степени устойчивости к абиотическим факторам среды выращивания. Косвенно эту устойчивость можно оценить по количественным изменениям пигментного состава. Практический интерес представляет сравнение работы пигментного комплекса флаговых листьев сортов пшеницы разных групп спелости, что может дать информацию о направлении селекционного улучшения физиолого-генетических признаков растений в различных экологических условиях. Растения 9 селекционных линий и 2 сортов-стандартов выращивали в 2016-2018 гг. на опытном поле ФАНЦ Северо-Востока (г. Киров) в условиях континентального климата с умеренно холодной зимой и теплым летом. Исследование пигментного комплекса флаговых листьев в фазу цветения позволило выявить отличия раннеспелых и среднеспелых генотипов по изучаемым параметрам в разных гидротермических условиях. В среднем за годы изучения среднеспелые генотипы накапливали больше хлорофилла а , чем раннеспелые; это превышение составило около 10%. Изученные сорта различались распределением пигмента между структурными частями фотосистем: у среднеспелых линий больше хлорофилла a содержалось в реакционных центрах, тогда как количество хлорофилла a в светособирающих комплексах не отличалось. Гидротермические условия конкретного года значимо влияли на различия между группами сортов. Так, в засушливых условиях содержание хлорофилла b и каротиноидов во флаговых листьях у сортов двух групп спелости значимо не отличалось. Но в нормальных и влажных условиях среднеспелые сорта по сравнению с раннеспелыми содержали хлорофилла b на 11,0-12,6% больше, каротиноидов на 7,6-23,1%. В засушливых условиях две группы сортов значимо различались по массовому соотношению хлорофиллов a и b : у среднеспелых сортов оно было на 5,0% выше, чем у раннеспелых. По содержанию хлорофиллов a и b в фазу цветения в группе среднеспелых сортов выделены селекционные линии С-64, С-65, С-103, С-129. Количество хлорофиллов у этих генотипов статистически значимо превысило показатели стандартного сорта Маргарита. В раннеспелой группе селекционные линии по содержанию пигментов находились на уровне стандарта Баженка. Сорта этой группы сильно реагировали на изменение абиотических условий выращивания (количество выпадающих осадков и температуру воздуха): коэффициенты вариации содержания хлорофилла a имели значения 6,5-16,3%, содержания хлорофилла b 26,9-29,7%, каротиноидов 4,1-17,2%., Creation of new higher productive cultivars of cereal crops is often linked with straightening of degree of resistance to abiotic environmental factors. Indirectly this degree of resistance could be estimated on quantitative change in leaf pigment composition. There is practical interest to compare the activity of pigment complex of flag leaves of wheat cultivars belonging to different maturity groups that could give information on direction of breeding improvement of plant physiological-and-genetic traits under different ecological conditions. Plants of nine breeding lines and two standard cultivars grew in 2016-2018 at the experimental field of FARC of North-East (Kirov) under continental climate conditions with moderately cold winter and warm summer. The study of flag leaves pigment complex allows to discover differences between early and middle-ripening cultivars on investigated parameters in different hydrothermal conditions. During the study years, middle-ripening cultivars accumulated more chlorophyll a than the early ones. On average this excess was about 10%. The studied cultivars were differed on distribution of pigment between structural parts of photosystems: middle-ripening cultivars had more chlorophyll a in reaction centers whereas the amount of the pigment in light-harvesting complexes was not differed. Hydrothermal conditions significantly influenced the differences between cultivar groups. Thus, under dry conditions the content of chlorophyll b and carotenoids in flag leaves of cultivars belonging to both group of maturity had no significant differences. Under normal or moist conditions middle-ripening cultivars contained 11,0-12,6% more chlorophyll b and 7,6-23,1% more carotenoids than the early cultivars. Under dry conditions the two groups of cultivars significantly differed on mass ratio chlorophyll a/b: in the middle-ripening cultivars it was 5,0% higher than in the early ones. Based on chlorophyll a and b content at flowering stage breeding lines С-64, С-65, С-103, and С-129 were selected. The amount of chlorophyll in these genotypes was significantly higher than in Margarita standard cultivar. Within the group of early cultivars, no one exceeded Bazhenka standard by the pigment content. The cultivars of this group reacted on abiotic growing conditions change very much (the amount of precipitations and air temperature): the coefficients of chlorophyll a content variation were 6,5-16,3%, of chlorophyll b content 26,9-29,7%, of carotenoids content 4,1-17,2%.

The experiment was conducted in greenhouse conditions at Vietnam National University of Agriculture to investigate genotypic variation in morphological and physiological responses of five soybean cultivars to waterlogging at the flowering stage. Seeds of each cultivar were sown in pots containing 6 kg dry soil. At early flowering stage, treatment pots were subjected to waterlogging by maintaining the water level of 3 cm above the soil surface for ten days. The results showed that the nodule number, nodule dry weight, chlorophyll content, carbon exchange rate, dry matter accumulation and nitrogen content were significantly reduced in waterlogging conditions. Among soybean cultivars, D140 and D912 showed better root length, nitrogen accumulation and total biomass under waterlogging conditions. Breeding for higher root growth, maintaining high nitrogen accumulation and total biomass could be an important strategy to improve soybean cultivar for waterlogging tolerance.

To investigate effects of drought stress on yield and yield components of sesame in Kerman region a split-plot experiment based onn compelet randomised block design with three replications was carried out in 1388. Irrigation levels (Normal irrigation in all growth stages, witholding water after 50% flowering, witholding water after 50% pod setting) and differen t sesame landraces (Jiroft, Shiraz, Ardestan, Dezful, Shahr babak, Gorgan, Sirjan, Markazi, Birjand and Orzueieh) were considered as main plots and sub-plots respectively. Plant height, the biggest pod length, noumber of grain per pod, noumber of pod per plant, grain weight per plant, thousand grain weight and grain yield were the measured traits. Results showed all the measured traits were significantly affected by the irrigation treatments. The effects of different landraces on all traits except noumber of grain per plant were significant. Irrigation × landraces interaction affected all measured traits except the biggest pod length significantly. The highest grain yield was recorde for Markezi landrace (845.2 kg –ha) under normal irrigation and the lowest one was obtained from Jiroft landrace (104.8 kg –ha) with witholding irrigation after 50% flowering.

تولیدات کشاورزی شدیدأ تحت تأثیر شوری خاک و اثرات مخرب غلظت نمک در خاک­های شور می­باشند و این عامل تمدن کشاورزی قدیمی و مدرن را تحت تأثیر قرار داده است. به­منظور بررسی اثر تنش شوری آب برتعدادی از صفات مورفولوژیکی و فیزیولوژیکی مرتبط با مقاومت به شوری در دوازده رقم کلزای بهاره، آزمایشی بصورت کرت­های خرد شده با سه سطح شوری صفر، 150و 300 میلی­مولار در قالب طرح بلوک­های کامل تصادفی با سه تکرار به اجرا درآمد. در این پژوهش صفات ارتفاع بوته، طول ریشه، وزن­تر و خشک گیاه، وزن­تر و خشک ریشه، وزن صد ­دانه، عملکرد دانه در بوته، پتانسیل اسمزی، پتانسیل آب برگ، پرولین، Na+برگ، K+برگ و K+/Na+برگ ارقام اندازه­گیری شد. تجزیه واریانس حاکی از وجود اختلاف معنی­دار بین ارقام مورد مطالعه برای تمامی صفات بود. از تجزیه­خوشه­ای با روش UPGMA برای گروه ­بندی ارقام از حیث کلیه صفات و برای تمامی سطوح شوری استفاده شد. تجزیه­خوشه ­ای در شرایط تنش شوری شدید منجر به تشکیل دو خوشه گردید که ارقام Heros و Comet در اکثر صفات مورد مطالعه میانگین کمتری را به خود اختصاص دادند، لذا می­توان از آن­ها بعنوان والدین حساس در تلاقی با ارقام متحمل مانند Crakerو Amica جهت تهیه جوامع مناسب برای ترسیم نقشه ژنتیکی و مکان­یابی صفات کمی درگیر در مقاومت به شوری استفاده کرد. با شناسایی ارقام متحمل و حساس به شوری زمینه برای مطالعات مولکولی جهت درک درست سازوکار تحمل به تنش شوری در کلزا و ژن­های درگیر در این فرآیند فراهم خواهد شد.

Mentha × piperita (L.) Huds. of the family Lamiaceae is a very important species for commercial exploitation due to the high content of essential oil. Besides the essential oils, there are also other significant secondary metabolites in peppermint, especially flavonoids and hydroxycinnamic derivatives. In this study, we evaluate the variability of essential oil constituents and of phenolic compounds in the leaves of M. × piperita during the development of inflorescence. Similar studies, dealing with the variation of the essential oils and its composition, have been performed in the past, but no attention was paid to the variation of other secondary metabolites. We examined M. × piperita cv. ‘Perpeta’, the domestic cultivar. The plants were cultivated in the climatic conditions of south-west Slovakia. The contents of secondary metabolites were investigated in the week periods, from the beginning of inflorescence formation to the end of flowering. The yield and the quality of essential oil have been carried out by distillation and gas chromatography mass spectrometry (GC-MS). The phenolic substances were analysed using spectrophotometric methods according to European Pharmacopoeia. The highest contents of phenolic substances have been found in leaves of plants during the flowering phenophase, the same stage when essential oil of mint also achieves the highest quality.

Application of microelements is one of the ways to increase quantative and qualitative characters of wheat. To evaluate the effect of zinc foliar application on yield and yield components of four wheat cultivars a factorial experiment with two factors was conducted in randomized complete blocks design with three replications in 2011-2012 year. The first factor consisted of four wheat cultivars (Falat, Bahar, Pishtaz and Tous) and the second factor composed of three levels of zinc chelate foliar applications (control, at shooting stage and at shooting + flowering stages). Zinc concentration in each application was decided to be 4 kilogram per hectare. Results showed that yield and yield components of cultivars were significantly different with each others. The highest and lowest yields were belonged to Bahar and Tous respectively. The highest yield of Bahar, as compared to the other cultivars, was due to its higher biological yield. Zinc foliar applications at shooting and shooting + flowering stages also increased biological and seed yields. Seed yield increase mainly affected by higher 1000 seed weight. In general, it seems that zinc application, due to its role in the physiology of wheat, a sensitive plant to zinc deficiency, may increase its seed yield.

Chemical composition and antioxidant activity of Opuntia microdasys flowers in different maturity stages was evaluated. Fructose, glucose, sucrose and trehalose were found; oxalic, quinic, malic, and citric acids were also detected; five hydroxycinnamoyl, two kaempferol and six isorhamnetin derivatives; 23 fatty acids were quantified in all stages, except C20:2, which was only found in post flowering stage (F3); alpha-, beta-, gamma-, and delta-tocopherols were quantified in all samples. The highest contents in soluble sugars and phenolic compounds were detected in full flowering stage (F2), while organic acids and tocopherols were predominant in vegetative stage (F1). The highest levels of saturated, monounsaturated and polyunsaturated fatty acids were found in F3, F2 and F1, respectively. F1 gave the highest antioxidant activity. Principal components analysis showed clearly individualized groups corresponding to each flowering stage, identifying the most distinctive features, which might be useful to select a flowering stage for incorporation in functional foods. (C) 2014 Fundação para a Ciência e a Tecnologia (FCT, Portugal) for financial support to CIMO (strategic project PEst-OE/AGR/UI0690/2011), João C.M. Barreira (SFRH/BPD/72802/2010 grant) and L. Barros (“Compromisso para a Ciência 2008” contract). The GIP-USAL is financially supported by the Spanish Government through the Consolider-Ingenio 2010 Programme (FUN-C-FOOD, CSD2007-00063).

Seven species of oat ( Avena ) were evaluated for their relative drought tolerance under soil moisture stress. The plant height, leaf area production and biomass yield reduced under soil moisture stress. Among the species tested, minimum reduction in height was recorded in Avena vaviloviana , Avena abyssinica and Avena sterilis at vegetative and flowering stages. Significant decrease in leaf area production was recorded at vegetative stage, whereas at flowering stage, the decrease in leaf area production was marginal in A. sterilis followed by A. abyssinica predicting their more adaption to stress environment. The increase in specific leaf weight (SLW) of all the species of Avena showed increase in leaf thickness, exhibiting high water retention capacity under soil moisture stress condition which is a requisite trait for drought tolerance. Soil moisture stress imposed at vegetative and flowering stages reduced fresh biomass yield in all the species. Minimum reduction in dry biomass accumulation under stress environment at vegetative stage was recorded in A. sterilis followed by A. strigosa and A. sativa , exhibiting their tolerance to drought at early stages of growth. However, at flowering stage, minimum decrease in dry biomass production was recorded in A. sterilis (3.47%) followed by A. marocana (12.56%) indicating their relative drought tolerance at flowering stage of crop growth. A significant positive correlation between total leaf area and dry biomass (r 2 =0.738) under stress environment indicates that dry biomass accumulation was governed by total leaf area production. A. sterilis accumulated maximum fresh and dry biomass under soil moisture stress with minimum reduction over the non stress environment, indicating its drought tolerance potential as compared to other genotypes tested. Keywords: Avena , biomass, flowering stage, leaf area, soil moisture stress, vegetative stage.

Lotus tenuis forage yield has been quantified under defoliation conditions in pastures, grasslands and under dual-purpose production of both livestock forage and seeds. However, little is known about the effects of defoliation management on L. tenuis flower and pod production and subsequent seed yield. Two field experiments were conducted to study the response of L. tenuis to defoliation at different flowering stages and intensities. In Experiment 1, crops were defoliated at the beginning of the flowering (DBF), mid-flowering (DMF) or full flowering (DFF). In Experiment 2, defoliation was in vegetative stage at low (LDI) or high (HDI) intensities. Defoliation in Experiment 1 neither affected plant cover nor the photosynthetically active radiation intercepted by the crop during pod production. There were less umbels with dehiscent (shattered) pods in the DFF treatment than in Control, DBF and DMF treatments. Flower peak occurred first in the Control, DBF and DMF treatments, and eight days later in DFF plots, however, seed yield was not affected (1324 ± 32.8 kg·ha-1). Defoliation intensity did not affect seed yield (962 ± 25.9 kg·ha-1) because of self-compensation which increased harvest index in HDI (14.5% ± 0.6%) compared to the Control and LDI (12.0% ± 0.3%) treatments. Plant survival was not affected by defoliation treatments in any of the experiments. Flowering can be synchronized through defoliation. The blooming of large numbers of flowers in a short time was achieved, reducing the number of shattered pods. Compensatory responses through plant plasticity conferred L. tenuis the ability to overcome defoliation without affecting seed yield. Lotus tenuis defoliation as management tool will be considered in future researches because it is possible to harvest forage and to increase seed yield through a reduction of shattered pods. EEA Balcarce Fil: Vignolio, Osvaldo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agriarias; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina Fil: Cambareri, Gustavo Sebastián. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agriarias; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina Fil: Petigrosso, Lucas R. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agriarias; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina Fil: Murillo, Natalia Lorena. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agriarias; Argentina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina Fil: Maceira, Nestor Oscar. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agriarias; Argentina

To investigate the effect of drought stress and plant density on yield and yield components of maize KSc 301 hybrid, a two-year study (2007-2008) was carried out in Varamin Agricultural Research Center by using strip split plot randomized based on complete block design in three replications. Four water stress levels (before flowering, during flowering and grain filling stage and no stress) were assigned as vertical factor and three plant densities (60, 75 and 90 thousand plants ha-1), were assigned made up of horizontal factor. The effects of water stress and plant density were statistically significant on yield and its components. Water stress at flowering stage reduced the grain yield by 42% compared to the control treatment. Water stress before flowering and grain filling periods, although yield was significantly lower than control but there was no significant difference between treatments. Reduce the number of grains per ear and increased the interval between the pollination of flowers until silking were the main reasons for reduced yield in the treatment of water stress at the flowering stage. Density of 75 thousand plants ha-1 was determined the best density for grain yield. Among the tested density, density of 90 thousand plants ha-1, compared to the control treatment had the greatest reduction in yield (25% reduction). Water stress and plant density interaction was statistically significant at 1% level. The highest and lowest grain yield, respectively, related to the 75 thousand plants ha-1 and without water stress (9100kg ha-1) and water stress at the flowering stage and 90 thousand plants ha-1 (3700 kg ha-1).Water stress at flowering stage, and densities of less than 75 thousand plants ha-1 or higher than 75 thousand plants ha-1 was significantly decreased harvest index. The results showed that the density of 75 thousand plants per hectare and avoid stress, especially at the flowering stage appropriate yields can be expected from hybrid KSc 301.

Two rice genotypes with different drought tolerance, namely Jin 23B (drought tolerant) and Zhenshan 97B (drought sensitive), were used to study the antioxidant enzyme activities, soluble sugar and starch contents in spikelets, pistil water potential and pollen number on a stigma under water-deficit stress at the flowering stage, which were involved in the spikelet sterility. Compared with respective controls, drought stress induced more serious decreases of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities and more significant increase of malonaldehyde (MDA) content in spikekets of Zhenshan 97B than in Jin 23B on 9 and 12 days after water stress (DAWS). The soluble sugar and starch contents increased significantly in spikelets of Jin 23B, but decreased significantly in spikelets of Zhenshan 97B during 9-12 DAWS. The pistil maintained higher water potential in Jin 23B than in Zhenshan 97B during 3-6 DAWS and 9-12 DAWS. In addition, water stress induced more significant decrease in the pollen number on a stigma as well as the percentage of unfilled grains in Zhenshan 97B than in Jin 23B. Thus, it is suggested that water stress induced spikelet sterility by damaging antioxidant enzyme activities, reducing carbohydrate content in spikelets and decreasing pistil water potential at the flowering stage in rice.

The present paper presents the results of the research carried out on forty sunflowerhybrids in southern Romania (15 km far from northeastern Bucharest), under the2004 and 2006 climatic conditions, regarding the flowering stage, the period andthe duration of flowering process within the crop, respectively. The studied hybridswere the following: Favorit, Festiv, Florina, Jupiter, Alcazar, Top 75, Venus, Alex,Saturn, Minunea, HS 2442, HS 2606, Milenium, Romina, Performer, Select, Justin,Splendor, Hercule, Felix, and twenty foreign hybrids cultivated in Romania:Huracan, Kasol, Lindor, Masai, Mateol, Podium, Saxo, Sunko, Fly, Rigasol, RigasolOR, Fleuret OR, Arena, Melody, NK Armoni, Alexandra, NK Dolbi, NK Ferti,Opera PR, Sanay. At the studied sunflower hybrids were performed the following determinations: • sum of growing degree days (GDD) from plant emergency (i.e. when 75% ofthe plants emerged) to the beginning of the flowering process within the crop(i.e. when 10% of the sunflower heads are flowered); • date for the first sunflower heads flowering; • date for the beginning of the flowering process, i.e. when 10% of the sunflowerheads have flowered in the whole crop; • date for the plain flowering phase, i.e. when 50% of the total sunflower headshave flowered; • date for the full-flower phase, i.e. when all the sunflower head in the crop haveflowered; • date for the time when only 10% of the sunflower heads were still in flower; • date for the end of flowering, i.e. when no sunflower heads are in flower in thewhole crop; • number of days between different flowering stages.

Northern Japan, Hokkaido has cold weather damage in agriculture almost every four years. Cold weather damage to soybeans [Glycine max (L.) Merr] during flowering is especially severe and is caused by both low temperature and insufficient sunlight. Therefore, the damage should be analyzed from both aspects. We analyzed the effects of low temperature and shading during the flowering season on seed yield and yield components in two varieties of soybeans : cv. Hayahikari, an excellent cold weather tolerant variety, and cv. Toyomusume, a cold weather sensitive variety. The soybean plants were exposed to a low temperature of 18°C day/13°C night, shaded (50%) without low temperature treatment, or shaded at a low temperature, during the four-week flowering season. The control plants were kept under normal conditions. The results indicated that cold weather damage is mainly caused by the low temperature, which severely reduced the number of pods per plant, in Toyomusume. However, shading also reduced the number of pods per plant in both varieties. All of the yield components examined were reduced by cold weather more severely in Toyomusume than in Hayahikari. Furthermore, shading combined with low temperature treatment caused greater damage in both Hayahikari and Toyomusume than either a low temperature or shading treatment alone.

The effects of short-term exposure to a low temperature [two weeks, at 18°C/13°C (day/night) ] and long -term exposure to a low temperature [four weeks, at 18°C/13°C (day/night) ] from the beginning of flowering on pod setting were examined in one of the most cold-weather tolerant variety cv. Hayahikari and a standard sensitive variety cv. Toyomusume. The short-term exposure to a low temperature did not decrease the total number of pods even in Toyomusume. However, pod setting ability during the low temperature exposure was higher in Hayahikari than in Toyomusume. After the short-term exposure to a low temperature, pod setting showed recovery from the cold-weather damage by compensative pod setting after the low temperature treatment in both varieties. The long-term exposure to a low temperature significantly decreased the total number of pods in Toyomusume. But Hayahikari showed a greater capacity for pod setting during the low temperature. And the mechanism of tolerance was related to a superior fertilization ability during the low temperature.

After a spring frost occurred in second half of March 2008, with temperatures below 0°C for 8 days consecutively and an absolute minimum of -5.5°C, a lot of observations have been made on the sweet cherry flowers damages. In three different orchards “Italian palmetta” trained on grassing ground soil, the percentage of the flowers killed by frost, was detected and recorded considering the different genotypes and flowers height from the ground. Furthermore, in one orchard only it was possible to find relationship between flowering stage and frost damage. The results clearly confirm our previous works about the highest mortality of the flower in the upper part ( > 1.50 m) of the canopy and in the full bloom open flowers. So, in this area, the easiness of agronomic operations, like pruning and, especially, fruit harvest, due to the crown proximity to the ground, is cancelled by the frequency of spring frost.

Eleven isolates of identified six different pathotypes of Bipolaris sorokiniana were compared for their effect on leaf blight severity and yield contributing characters of wheat cv. Kanchan by inoculating plants at maximum tillering stage under control condition in pot trials. The pathotypes differed among themselves in respect of leaf blight severity that scored from 71 to 82. But the pathotypes did not differ among themselves regarding their effect on grain yield of wheat.

This article 'Resistance to Whitebacked Planthopper (WBPH) At Flowering Stage' appeared in the International Rice Research Newsletter series, created by the International Rice Research Institute (IRRI). The primary objective of this publication was to expedite communication among scientists concerned with the development of improved technology for rice and for rice based cropping systems. This publication will report what scientists are doing to increase the production of rice in as much as this crop feeds the most densely populated and land scarce nations in the world.