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• Sanqi flowers have a higher quality under organic vs conventional management. • The flavonoid biosynthesis pathway was positively influenced by organic management. • The full blooming stages is the best time to harvest the Sanqi flowers. The simulative habitat cultivation of Panax notoginseng (Sanqi) under pine forests using organic management (OM) enhances the quality of Sanqi roots. However, the impact of the OM on the quality of Sanqi flowers remains unknown. The Sanqi flowers cultivated under OM compared with those cultivated under CM (conventional management) exhibited higher levels of flavonoids, saponins, and polysaccharides, as well as dry/fresh weight. Principal component analysis demonstrated that metabolites were predominantly influenced by the cultivation patterns followed by the flowering stage. Several of the differentially abundant metabolites and expressed genes were upregulated in Sanqi flowers cultivated under OM. The flavonoid biosynthesis pathway was highly affected by the cultivation systems and flowering stages, mediated by the essential genes C4H, HCT, C3′H, DFR, and FLS. Flavonoid levels peaked at full bloom, indicating that this is the optimum stage for harvesting Sanqi flowers. Our findings are of great value for developing optimal cultivation and harvest practices. [ABSTRACT FROM AUTHOR]

Abstract Global warming has caused frequent occurrence of heat stress at the flowering stage of single-season rice in the Yangtze River region of China, which results in declines of spikelet fertility and yield in rice. Rice flowering stage is the most sensitive period to high temperatures, and therefore, the key for heat stress happening is the flowering stage coinciding with high temperature, which causes spikelet fertility decreasing in heat-sensitive varieties, and is the major factor for heat injury differences among various rice planting regions. With the development of rice breeding, temperature indexes for heat stress has been converted from daily maximum temperature of 35 °C to 38 °C with the stress duration of more than 3 d. During the flowering stage, anther dehiscence inhibition and low pollen shedding onto the stigma are two main reasons for spikelet fertility reduction under high temperatures. At panicle initiation stage, high temperatures aggravate spikelet degeneration, and destroy floral organ development. Various types of rice varieties coexist in production, and indica-japonica hybrid rice demonstrates the highest heat resistance in general, followed by indica and japonica rice varieties. In production, avoiding high temperature is the main strategy of preventing heat stress, and planting suitable cultivars and adjustment of sowing date are the most effective measures. Irrigation is an effective real-time cultivation measure to decline the canopy temperature during the rice flowering stage. We suggested that further study should be focused on exploring heat injury differences among different rice variety types, and innovating rice-planting methods according to planting system changes in rice planting regions with extreme heat stress. Meanwhile, high temperature monitor and warning systems should be improved to achieve optimal heat stress management efficiencies. [ABSTRACT FROM AUTHOR]

Abstract To understand the reallocation of organic nitrogen from leaf to the flower head of rice, the role of glutamine synthetase (GS) was investigated by characterizing GS1 RNAi transgenic rice, which revealed a significant reduction in panicle number and number of seeds per panicle. We observed the expression of GS isotypes at transcriptional and protein levels in flag leaves, leaf sheaths and panicles at three different flower development stages. The mRNA expression of GS1;1 was clearly suppressed in flag leaves, especially at the flowering stage. GS1 protein was barely detectable in flag leaves until the flowering stage, while GS1 protein was compromised in the leaf sheath and panicle, with transient expression of GS2 protein at the flowering stage. The glutamine level in transgenic plants was significantly reduced in both flag leaves and panicles, but ammonium was highly accumulated. The level of other amino acids, including aspartate and asparagine, tended to be higher in RNAi transgenic plants than the wild type plants during the reproductive stage. In addition, accumulation of toxic ammonium in panicles with low glutamine level might have caused low seed-setting in the transgenic rice. These results indicated that nitrogen reallocation was critical for panicle development, and that multiple GS isotypes functioned cooperatively to complete the rice life cycle when leaf nitrogen was remobilized to the developing reproductive organs. [ABSTRACT FROM AUTHOR]

In rice growing regions where water and temperature are growth limiting factors, the use of the innovative water-saving ground cover rice production system (GCRPS) leads to a substantial increase in yields and water use efficiency. However, so far the effect of GCRPS on root growth and its possible contribution to the observed increases in yield and water use efficiency remained unclear. In order to fill in this knowledge gap, we conducted a three-year experiment comparing two production systems: traditional paddy (Paddy) and GCRPS combined with two nitrogen fertilizer regimes (0, 150 kg N ha −1 ). The parameters investigated were root dry matter, length density and surface area at maximum tillering and flowering stage as well as grain yield and water use efficiency. Our study revealed the following findings: 1) Root dry matter, root length density and surface area were significantly higher in GCRPS than in Paddy at all soil depths. 2) Across the production systems, root dry matter, root length density and surface area at soil depth of 0–40 cm at flowering stage were significant positively correlated to grain yield and total water use efficiency which suggested that improved root morphology traits, especially at flowering stage, contribute to higher grain yield and water use efficiency in GCRPS. Our results show that GCRPS has a positive effect on the development of rice roots and that the improved root development is of vital importance for higher yields. Furthermore, the improved root development in GCRPS may avoid potential lodging phenomena and increase soil organic carbon stocks, thus improving key soil functions. [ABSTRACT FROM AUTHOR]

Salicylic acid (SA) induced drought tolerance can be a key trait for increasing and stabilizing wheat production. These SA induced traits were studied in two Triticum aestivum L. varieties; drought tolerant, Kundan and drought sensitive, Lok1 under two different water deficit regimes: and rehydration at vegetative and flowering stages. SA alleviated the negative effects of water stress on photosynthesis more in Kundan. SA induced defense responses against drought by increasing antioxidative enzymes and osmolytes (proline and total soluble sugars). Differential proteomics revealed major role of carbon metabolism and signal transduction in enhancing drought tolerance in Kundan which was shifted towards defense, energy production and protection in Lok1. Thioredoxins played important role between SA and redox signaling in activating defense responses. SA showed substantial impact on physiology and carbon assimilation in tolerant variety for better growth under drought. Lok1 exhibited SA induced drought tolerance through enhanced defense system and energy metabolism. Plants after rehydration showed complete recovery of physiological functions under SA treatment. SA mediated constitutive defense against water stress did not compromise yield. These results suggest that exogenously applied SA under drought stress confer growth promoting and stress priming effects on wheat plants thus alleviating yield limitation. Biological significance Studies have shown morphological, physiological and biochemical aspects associated with the SA mediated drought tolerance in wheat while understanding of molecular mechanism is limited. Herein, proteomics approach has identified significantly changed proteins and their potential relevance to SA mediated drought stress responses in drought tolerant and sensitive wheat varieties. SA regulates wide range of processes such as photosynthesis, carbon assimilation, protein metabolism, amino acid and energy metabolism, redox homeostasis and signal transduction under drought. Proteome response to SA during vegetative and reproductive growth gave an insight on mechanism related water stress acclimation for growth and development to attain potential yield under drought. The knowledge gained can be potentially applied to provide fundamental basis for new strategies aiming towards improved crop drought tolerance and productivity. [ABSTRACT FROM AUTHOR]

[Display omitted] • V cmax25 , N a and Chl a of winter wheat and paddy rice exhibited distinguishable seasonality. • The seasonality of leaf N a and Chl a were inconsistent with that of V cmax25. • Differentiating pre- and post-flowering stages significantly improved the estimation of V cmax25 from Chl a. Accurate representation of photosynthetic capacity and its seasonal variations is critical for modeling carbon sequestration of cropland ecosystems through photosynthesis. Previous studies indicated that the maximum carboxylation rate at 25 °C (V cmax25) is the key determinant of photosynthetic capacity and can be mapped according to leaf nitrogen (N) and chlorophyll (Chl) contents. However, whether relationships of V cmax25 with leaf nitrogen and chlorophyll contents in cropland ecosystems change over the whole growing season remain unclear. To address this question, we conducted intensive field campaigns in winter wheat and paddy rice farmlands of Eastern China, with leaf V cmax25 , the maximum electron transport rate at 25 °C (J max25), N, and Chl measured every 7 to 10 days from the tillering stage to maturity. Results showed that V cmax25 and J max25 varied significantly during the growing seasons and maximized at flowering stages. For both winter wheat and paddy rice, Chl a (Chl content at the area unit) showed significantly different relationships with V cmax25 pre- and post- flowering while N a (N content at the area unit) did not. When different empirical models were used for pre- flowering and post- flowering stages, V cmax25 estimated from Chl a was closer to observations (R2 = 0.875, RMSE = 9.479 µmol m−2 s−1) than that estimated from N a (R2 = 0.565, RMSE = 17.718 µmol m−2 s−1). The findings in this study imply that the combination of remotely sensed leaf Chl a content and phenology would improve the mapping of V cmax25 for crops at regional and even global scales. [ABSTRACT FROM AUTHOR]

Highlights: [•] Flowers of Opuntia microdasys were profiled for hydrophilic and lipophilic compounds. [•] Significant differences were detected according to the flowering stage. [•] The chemical profiles of each flowering were classified in different clusters using PCA. [•] The antioxidant activity levels were coherent with the bioactive compounds contents. [•] These results are useful to select specific flowering stages for functional foods. [Copyright &y& Elsevier]

Abstract: The chemical composition of hexane extracts from flowers belonging to two species of prickly pear, Opuntia ficus-indica (L.) Miller and Opuntia stricta (Haw.) Haworth has been studied by gas chromatography–mass spectrometry in four developmental stages of flower: vegetative, initial flowering, full flowering, and post-flowering stages. Remarkable differences were noted between the flowers’ compositions. The main compounds were carboxylic acid (28–97%), terpenes (0.2–57%), esters (0.2–27%), and alcohols (<1.8%). The study of the biological activities showed that extracts were active in vitro towards four bacteria and two fungal strains. It exhibited remarkable activity against Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. Antioxidant activity of the flowers extracts was evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical method. Our findings demonstrate the interest of Opuntia flowers extract as a source of bioactive substances and its potential preservative use in food. [Copyright &y& Elsevier]

Abstract: 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. [ABSTRACT FROM AUTHOR]

Abstract: Flowering time plasticity is a commonly occurring adaptive characteristic of fodder crops, including legumes, in arid and semiarid environments of the Mediterranean regions. Time of flowering is mainly influenced by genotype, temperature and photoperiod. Field experiments were carried out at Foggia (southern Italy) during successive growing seasons (from 8 to 16 growing cycles according to species) to study the relation among air temperature, photoperiod and duration of the morphological development of flowering in eight forage legume species: sulla (Hedysarum coronarium L.), sainfoin (Onobrychis viciifolia Scop.), pea (Pisum sativun L.), berseem clover (Trifolium alexandrinum L.), Persian clover (Trifolium resupinatum L.), faba bean (Vicia faba L.), common vetch (Vicia sativa L.) and hairy vetch (Vicia villosa Roth). Time to reach 10% flowering (EF) and 100% flowering (FF) were recorded. Rate of progress to flowering, defined as the inverse of time from sowing to EF and FF, was related to mean daily temperature, or to both mean daily temperature and mean photoperiod. Using the linear equations, the thermal time requirements (T t) and the base temperature (T b) expressed as heat units were determined by the x-intercept method for both EF and FF stages. Evaluation of flowering time was also based on days after planting (DAP), day of year (DOY) and on a photothermal index (PTI). For all species, a significant negative correlation (P ≥0.01) was found between planting date (PD) and DAP whereas PTI showed a significant negative relationship (P ≥0.05) only for faba bean, pea, berseem clover and common vetch. In sainfoin, sulla and berseem clover, the rate of progress to flowering was affected significantly (P ≥0.05) by both mean temperature and photoperiod. The T t requirements to reach the EF and the FF stage ranged from 871 to 1665°Cday and from 1043 to 1616°Cday, respectively, for the studied species. Both phenological stages considered depended upon accumulated thermal time above a species-specific base temperature. Furthermore, in all legumes the onset of flowering only occurred when dual thresholds of a minimum T t and a minimum photoperiod were reached, which were specific to each species. [Copyright &y& Elsevier]

Abstract: The Cd accumulation and biomass characteristics of a newly found Cd-hyperaccumulator Solanum nigrum L. were investigated at the flowering stage and the mature stage. The results showed that the concentration of Cd in the stems and leaves of S. nigrum harvested at the flowering stage was up to 83.1% and 85.5% of that at the mature stage, and the dry-weight sum of the stems and leaves of S. nigrum harvested at the flowering stage was 93.4% of that at its seed maturity. The Cd-removing ratio by the shoots of S. nigrum harvested at the flowering stage was 87.5% of that at the mature stage. It was also found by observing the growth duration of S. nigrum that the frostless period at the experimental site was at least twice as long as the growth duration from the seedling-transplanted phase to the flowering stage of the hyperaccumulator. Therefore, S. nigrum could be transplanted into contaminated soils twice in one year by harvesting the hyperaccumulator at its flowering stage based on climatic conditions of the site and traits of the plant growth. In particular, the extraction efficiency of Cd by harvesting the shoots of S. nigrum at its flowering stage twice in one year could increase 75.0% compared to that of at its single maturity. Thus, the method of multiple harvesting would be very important to increase phytoremediation efficiency in practice. [Copyright &y& Elsevier]

• Volatiles profiling of Egyptian Rosa damascena Mill. flowers at different stages was presented. • Differences in flowers aroma along with anti-collagenase effect were identified. • Alcohols, esters and oxides were detected at higher levels in expanded flowers. • Ultra-high performance liquid chromatography-mass spectrometry revealed 66 secondary metabolites in Egyptian rose. • Several sphingolipid conjugates and tannins were reported for the first time. Rosa damascena Mill. is well recognized for its value as an ornamental aromatic plant with several folk medicinal uses. As a valuable oil-bearing plant, its aroma profile was extensively studied, albeit differences between unexpanded rose flowers (URF) and expanded rose flowers (EFR) at different levels of blooming is not reported. Rose scent from both stages was determined using headspace solid-phase microextraction (HS-SPME) for the first time for Egyptian rose. A total of 75 volatiles were detected, with alcohols, esters, and oxides as valuable volatile classes at ca. 64 %, 10 % and 2 % respectively in ERF compared to 46 %, 2 %, and 0.4 % in URF. Egyptian rose aroma is considered of high quality being enriched in citronellol, geraniol, and phenylethyl alcohol (rose oil). Total flavonoids, phenolics, and anthocyanins were found more enriched in ERF than URF. Further, comprehensive ultra-high-performance liquid chromatography/photodiode array detector/electrospray ionization-mass spectrometry UHPLC/PDA/ESI-MS revealed 66 secondary metabolites, of which sphingolipid conjugates and tannins are first time to be reported in rose including several novel phenolics viz. , gallic acid-di- O -hexoside, galloyl hexose malic acid I, digalloyl-hexosyl-ellagic acid and levoglucosangallate I. Further, in-vitro anti collagenase assay revealed a strong effect for ERF compared to URF and in correlation to its metabolite fingerprint. The strong fragrant scent of Egyptian rose along with its anti-collagenase effect poses it for incorporation in cosmetics and skincare products. [ABSTRACT FROM AUTHOR]

• The EarSegNet outperformed SegNet and Two-stage method, providing robust results. • The EarSegNet was efficient at segmenting ears of winter wheat. • The encoder structure had no significant influence on the performance. • The EarSegNet had promising potentials for field applications. Fast and accurate segmentation of winter wheat ears from canopy images can significantly promote the field phenotyping of ears by improving efficiency. In this study, a semantic segmentation based method, i.e., EarSegNet, was proposed to perform pixel-wise classification to segment wheat ears from canopy images captured in field conditions. The EarSegNet integrated the encoder-decoder structure and dilated convolution, aiming to further improve the segmentation accuracy and efficiency for the ears of winter wheat. The results showed that the proposed EarSegNet was able to achieve accurate segmentation of wheat ears from canopy images captured at the flowering stage (segmentation quality = 0.7743, F1 score = 87.25%, structural similarity index = 0.8773). In order to validate the proposed method, the performance of the proposed EarSegNet was compared to the widely used segmentation methods, i.e., SegNet, Two-stage method, and Panicle-SEG. Results showed that the proposed EarSegNet outperformed the compared methods, making a robust and efficient tool to segment ears of winter wheat from canopy images captured at the flowering stage. Generalization tests showed that the proposed EarSegNet achieved superior performances to the compared method, suggesting that the EarSegNet had great potentials for field applications. Obtained results showed that the depths of the encoder, i.e., VGG16, had no significant influences on the performance of EarSegNet, however, deepening the VGG16 would improve the performance of the EarSegNet on the evaluation metric of recall. The results showed that the EarSegNet was a promising tool for ears of winter wheat at flowering stage. [ABSTRACT FROM AUTHOR]