Bloom Stage Research Articles

Effect of Preharvest Calcium Chloride Treatment on Some Quality Characteristics and Bioactive Compounds of Sweet Cherry Cultivars

The effects of preharvest calcium chloride (CaCl2) treatment on some quality characteristics and bioactive compounds of sweet cherry fruit (Prunus avium L. cvs. 0900 Ziraat, Sweetheart and Merton Late) were investigated. The CaCl2 (1%) solution was sprayed to the cherry trees at 21 and 35 days after full bloom stage. The trees served as control were treated with distilled water at the same days. CaCl2 treatment remarkably suppressed the respiration rate and increased titratable acidity and fruit firmness of cherries. Treated fruit had more attractive skin colour with higher h° and L* values compared to control. The individual soluble sugars and total sugar contents of CaCl2 treated cherries were lower than those of control fruit. The accumulation of ascorbic acid, stem chlorophyll, total phenolics and anthocyanin contents of fruit were delayed by CaCl2 treatment in all varieties. The antioxidant activities of all treated varieties were lower than those of control fruit. Based on these results, it can be set forth that preharvest CaCl2 treatment suppressed ripening processes including respiration rate and maintained firmness and titratable acidity of cherries by maintaining cell integrity in all varieties during the fruit development period.

Diversity, Pathogenicity, and Fungicide Sensitivity of Fungal Species Associated with Late-Season Rots of Wine Grape in the Mid-Atlantic United States.

Late-season bunch rots cause major losses in grape production every year in the Mid-Atlantic United States, but the causal agents are not well characterized. In this study, 265 fungal isolates were collected from rotten grapes from 2014 to 2020 and identified to the genus level according to internal transcribed spacer sequences. The most prevalent of the 15 genera were Botrytis, Colletotrichum, Aspergillus, Alternaria, Pestalotiopsis, and Neopestalotiopsis. Of these, isolates within three prevalent, yet understudied, genera were identified to be Aspergillus uvarum, Alternaria alternata, and Neopestalotiopsis rosae. The pathogenicity of these three fungal species was evaluated in two field trials by artificially inoculating wounded and nonwounded grapes (Vitis vinifera) of four cultivars at the phenological stages of bloom, véraison, and preharvest. Upon ripening, fruit were weighed and assessed for severity of multiple diseases. On nonwounded fruit, A. uvarum caused significantly higher disease severity than the control in both seasons. On wounded fruit, each inocula caused significantly higher disease than the respective controls in the first season, but only A. uvarum and Botrytis cinerea caused this in the second season. Also, wounding was found to have a detrimental effect on cluster weight, which was significantly influenced by inoculation timing and cultivar. Lastly, A. uvarum and N. rosae were tested for sensitivity to azoxystrobin, boscalid, and difenoconazole. The A. uvarum isolates were found to be more sensitive to boscalid and difenoconazole in general, with varying sensitivity to azoxystrobin. N. rosae isolates were resistant to boscalid and azoxystrobin but displayed much higher sensitivity to difenoconazole. Evidence from the isolate collection and field trials demonstrates that A. uvarum could be a significant pathogen of wine grapes in the Mid-Atlantic United States. Results from this study will be useful for the identification and management of the understudied Alternaria, Aspergillus, and Neopestalotiopsis fruit rots of wine grapes.

EARLY LEAF REMOVAL AS STRATEGY TO REDUCE BOTRYTIS BUNCH ROT ON CHARDONNAY GRAPEVINE IN HIGH ALTITUDE REGION OF SANTA CATARINA STATE

The objective of this work is to compare different periods of leaf removal in the control of this disease in Chardonnay grown in high altitude regions of Santa Catarina - Brazil. The experiments were conducted in São Joaquim city, in 2018 and 2019 growing seasons. The treatments consisted of leaf removal at the phenological stages of full bloom, buckshot berries, pea-sized berries, veraison, and the control treatment, in which the plants without leaf removal. Epidemiological variables were calculated from: beginning of symptom appearance; times to reach maximum disease incidence and severity; maximum disease incidence and severity; and areas under the incidence and severity disease progress curves. The results of the present work show the importance of early leaf removal of Chardonnay in management of B. cinerea, it is recommended to be carried out at the phenological stages of full bloom, buckshot berries and pea-sized berries, as it provides a reduction in the maximum severity of B. cinerea and a reduction of AUSDPC. The rate of disease progression demonstrated that B. cinerea infection and development was faster in plants not submitted to leaf removal. The management of early leaf removal is efficient to prevent the development of B. cinerea in Chardonnay.

A Study on the Volatile Compounds in Elaeagnus angustifolia L. Flowers during Flowering Season by Gas Chromatography-Mass Spectrometry Coupled with Advanced Chemometrics

The flowers of Elaeagnus angustifolia L. have been used as a homologous variety in China, whose quality seriously relies on the compositions during the flowering period. Unfortunately, studies on the variations of volatile compounds during the flowering season are rarely reported. Herein, a gas chromatography-mass spectrometry-based untargeted metabolomic methodology was proposed for the comprehensive analysis of volatile compounds in E. angustifolia flowers to classify various flowering stages. Samples from four flowering stages were collected, including the initial bloom stage, pre-full bloom stage (70–80% of flowers), full bloom stage, and ending of the bloom stage. Simultaneous distillation extraction was used for the extraction of volatile compounds in the flowers, which was then analyzed by a newly developed chemometric data analysis tool, autoGCMSDataAnal. An advantage of the developed methodology is that compounds can be accurately screened and identified. Finally, 59 compounds that showed significant difference among four flowering stages were screened and 31 compounds were identified. Sample clustering results from principal component analysis and hierarchical clustering analysis suggested that flowers from the pre-full bloom stage and full bloom stage may be more suitable when used as raw materials for industrial products.

The pre-eminence of agro-parameters and chemical constituents in the influence of harvest interval by traits × environment interaction over the years in lemon-scented basil (Ocimum africanum Lour.)

The lemon-scented basil (Ocimum africanum Lour.) is known for its pleasant lemon aroma and diverse medicinal uses. A field experiment was conducted in the two consecutive years, 2017–2018 and 2018–2019, at CSIR-CIMAP RC Hyderabad, India, on the effect of different harvesting intervals on agro parameters and chemical constituents of aromatic-cum-medicinal crop lemon-scented basil (Ocimum africanum Lour.). The study aims to standardize the appropriate harvesting time for the maximum essential oil yield with high citral content across the years/environments and recommendations for the best harvesting time. It is cleared from this investigation that the harvesting stage, traits, environment, and harvesting interval (H) × Years (Y), harvesting interval (H) × traits (T), traits (T) × years (Y), and harvesting interval (H) × traits (T) × years (Y) interactions play a vital role in operating the gene expression for the essential oil yield, and others quality characters in the O. africanum variety CIM Jyoti. The most appropriate harvesting stage is recommended at a full blooming stage in 75 days for maximum essential oil production.

Fish tissue accumulation and proteomic response to microcystins is species-dependent

Cyanotoxins including microcystins are increasing globally, escalating health risks to humans and wildlife. Freshwater fish can accumulate and retain microcystins in tissues; however, uptake and depuration studies thus far have not exposed fish to microcystins in its intracellular state (i.e., cell-bound or conserved within cyanobacteria), which is a primary route of exposure in the field, nor have they investigated sublethal molecular-level effects in tissues, limiting our knowledge of proteins responsible for microcystin toxicity pathways in pre-to-postsenescent stages of a harmful algal bloom. We address these gaps with a 2-wk study (1 wk of ‘uptake’ exposure to intracellular microcystins (0–40 μg L−1) produced by Microcystis aeruginosa followed by 1 wk of ‘depuration’ in clean water) using Rainbow Trout (Oncorhynchus mykiss) and Lake Trout (Salvelinus namaycush). Liver and muscle samples were collected throughout uptake and depuration phases for targeted microcystin quantification and nontargeted proteomics. For both species, microcystins accumulated at a higher concentration in the liver than muscle, and activated cellular responses related to oxidative stress, apoptosis, DNA repair, and carcinogenicity. However, intraspecific proteomic effects between Rainbow Trout and Lake Trout differed, and interspecific accumulation and retention of microcystins in tissues within each species also differed. We demonstrate that fish do not respond the same to cyanobacterial toxicity within and among species despite being reared in the same environment and diet.

Gm6PGDH1, a Cytosolic 6-Phosphogluconate Dehydrogenase, Enhanced Tolerance to Phosphate Starvation by Improving Root System Development and Modifying the Antioxidant System in Soybean.

Phosphorus plays an important role in plant growth and development, and is an important limiting factor for crop yield. Although previous studies have shown that 6-phosphogluconate dehydrogenase (6PGDH) plays an important role in plant resistance to adversity, its response to low phosphorus (P) stress remains unknown. In this study, we reported the cloning and characterization of a cytosolic 6PGDH gene, Gm6PGDH1, which enhanced the tolerance to phosphate (Pi) starvation by improving root system development and modifying the antioxidant system in transgenic plants. Gm6PGDH1 was highly expressed in the root at full bloom stage, and strongly induced by Pi starvation. The results from intact soybean composite plant and soybean plant, both containing a Gm6PGDH1-overexpressing construct, showed that Gm6PGDH1 was involved in root system development, and subsequently affected P uptake under Pi-deficient conditions. Meanwhile, the accumulation of reactive oxygen species (ROS) in the root tip of transgenic soybean was reduced, and the activity of ROS-scavenging enzymes was enhanced compared with those of the wild type under Pi-deficient conditions. Interestingly, we found that the overexpression of Gm6PGDH1 weakened the response of several other important Pi-answer genes to Pi starvation, such as some purple acid phosphatases (PAPs) and redox-related genes. In addition, the results from a virus-induced gene silencing (VIGS) indicated that Gm6PGDH1 might have functional redundancy in soybean, and the results from a heterogeneous transformation system showed that overexpressing Gm6PGDH1 also enhanced tolerance to Pi starvation in transgenic Arabidopsis. Together, these results suggested the great potential of Gm6PGDH1 in crop breeding for low Pi tolerance.

Potential of Urochloa grass hybrids as fodder in the Ethiopian highlands

AbstractUrochloa grasses have shownpromising results for smallholders to cope with feed shortages in tropical Africa. The objective of this study was to evaluate the performance of two Urochloa hybrids, Mulato‐I and Mulato‐II, in the Ethiopian highlands when managed under different plant spacing and harvesting stages. Treatments included three plant spacings for root splits (0.5 by 0.25 m, 0.5 by 0.5 m, and 0.75 by 0.75 m between rows and plants, respectively) and three harvesting stages: (a) 60 d of growth; (b) 90 d of growth corresponding to 50% bloom, and (c) 120 d of growth (corresponding to full bloom). Experimental plots were laid out in a randomized complete block design with three replications, and observations on the same established stands were made in two consecutive years. Varietal differences were observed in plant height (Mulato‐II: 42 cm; Mulato‐I: 72 cm), and herbage accumulation (Mulato‐II: 3.0 Mg dry matter [DM] ha–1; Mulato‐I: 10.6 Mg DM ha–1). Plant spacing also affected the above variables, but year of harvest influenced herbage accumulation. The rate of herbage accumulation tended to be constant, while that of crude protein (CP) declined and fiber concentration increased significantly with advancing maturity. Overall, the decline in quality at full bloom stage appears to be compensated by the greater herbage accumulation, suggesting that farmers can have enough time window to harvest the forages. While Mulato‐I was superior in herbage accumulation, Mulato‐II was found to be better in forage quality. The two grasses have potential to supply good quality forage provided proper management practices are applied.

Improvement of Fruit Quality and Marketability of “Washington Navel” Orange Fruit by Cytokinin and Gibberellin

The current investigation aimed to maximize the productivity of “Washington Navel” orange by reducing fruit splitting %, increase fruit weight and size, quality, in addition to improve marketability. So, in the 2016/2017 and 2017/2018 seasons a field experiment was carried out on a private orchard in Kafr El-Sheik governorate, Egypt. Trees were treated with Benzyladenin (BA) at 50ppm, Sytofix (CPPU) at 10ppm, GA3 at 50ppm, and GA3 combined with BA or CPPU. Plant growth regulators (PGRs) were applied three times after the full bloom stage by 15, 30 and 45 days as foliar application. Results revealed that PGRs increased quality parameters, productivity, and chlorophyll content, as well as reduced fruit splitting % and carotene content. GA3 plus CPPU gave the highest fruit fresh weight, fruit length, fruit yield, and SSC%. However, GA3+BA registered the greatest fruit diameter, chlorophyll content, TA%, vitamin C, as well as decreased fruit splitting % and carotene content. Regarding the marketing period, GA3 plus BA obtained the highest reduction % in weight loss, decayed fruit percentage, however, recorded the greatest vitamin C and chlorophyll contents. ABA results clarified that application of PGRs tended to decrease significantly its content in peel fruit, in particular, GA3 alone or combined with BA showed the lowest content of ABA in both seasons. These results will not only help researchers to understand the roles of PGRs in navel orange fruit growth, development, and productivity but can also be applied to large-scale fruit production and prolong the marketing period.

PHYSIOLOGICAL EFFECTS OF HIGH TEMPERATURE TREATMENTS ON TOMATO LEAVES AT TWO DEVELOPMENTAL PHASES

This study was conducted to investigate the effects of high temperatures on three tomato cultivars at first bloom and yield stages. The leaves were subjected to high temperature stress at 35, 40, 45, 50, 55 and 60°C with gradual increments every 30-minutes in both stages. Samples were analyzed for total chlorophyll (Chl), carotenoid (Car), ascorbic acid (AsA), glutathione (GSH), total soluble protein (TSP) contents. Besides, protein profiles were determined with SDS-PAGE. Heat stress decreased Chl content in both stages, while it was higher in first bloom stage than in yield stage. Whereas carotenoid content increased in both stages. The AsA and GSH contents were higher in yield stage than in first bloom stage. Heat stress, generally reduced AsA content, while increased GSH content. It was observed that the effect of cultivars and temperature treatments on the TSP content was different in both periods. In addition, TSP content had decreased with increasing temperatures, while many protein bands had been observed in SDS-PAGE with sizes ranging from 13 kDa to 89 kDa according to treatments.

Frost tolerance in apricot (Prunus armeniaca L.) receptacle and pistil organs: how is the relationship among amino acids, minerals, and cell death points?

To the better management of spring frost problem in the apricot cultivars, evaluation of biochemical changes in flower and/or flower organs during bud break could be one of the key factors. In this study, the relationship between the biochemical metabolites such as amino acids and minerals in the receptacle and pistil organs of two different apricot cultivars (frost-sensitive and frost-tolerant) and their relative effects on the frost tolerance of the cultivars and their organs were investigated during full blooming stage. In both apricot cultivars, it was found that the cell death points (CDP) of flower receptacle (- 6.3 to - 8.4°C) were at higher temperatures than the CDP of flower pistil organs (- 13.1 to - 14.5°C). Receptacle organs in flower, therefore, had less tolerance to spring frost damage. In addition, significant differences in mineral and amino acid contents were detected both between apricot cultivars and between the receptacle and pistil organs of the cultivars. Amino acid and mineral contents were lower both in the freezing-sensitive apricot cultivar ("Mihralibey") and the freezing-sensitive organ (receptacle) in comparison with the freezing-tolerant apricot cultivar ("Iğdır Şalak") and the freezing-tolerant organ (pistil). A significant negative correlation was also observed between the mean CDP values and both amino acid and mineral contents in the receptacle and pistil organs of both apricot cultivars. A negative correlation was found between CDP values and glutamate from amino acids and N, K, and Mg from minerals, and also these were determined that they had positive effects on frost tolerance increase. An important finding from our work revealed that the amount of each mineral and amino acid allocated differently to the receptacle and pistil organs of the apricot cultivars. The understanding of the amino acids and the mineral dynamics may contribute to improving the tolerance of flowers of apricot or other deciduous species to frost damage during spring. In the future, we may conclude that protection strategies such as increasing amino acids and mineral content in the receptacle organ of flowers would be necessary to cope with the negative effects of spring frost.

Mathematical Difficulties of 7th Grade MTs Students Analysis in Online Learning Based on The Realm Bloom’s Taxonomy

Online learning is a new alternative for the continuity of learning activities during the Covid-19 period, where learning is carried out online through various media or ICT used. This research aims to see the analyze how difficult students mathematical in working on mathematical problems, especially in quadrilateral and triangular material. The subject of this study were students of class VII at MTs Negeri Kabupaten Bandung Barat. The instrument used were written tests in the form of essays which numbered 5 questions and a student questionnaire via a google form. This research method uses descriptive analysis, to find out the student's mistakes in solving problems. Processing data is calculated in the form of average student scores obtained by analysis used on Taksonomi Bloom cognitive. The results showed that students achievement in the process of solving triangular and quadrilateral problems based on the stage of Taksonomi Bloom is based on the stage of Taksonomi Bloom, namely, at the cognitive stage the most is in stage C5 and C6 there is evaluation and creation, then in C2, C3, and C4 also still less than 60%. Thus it can be seen that the level of student understanding of rectangular and triangular material is still relatively low so that there is difficulty in solving students' problems on rectangular and triangular material based on Taksonomi Bloom stages.
 Keywords: student difficulties, online learning, quadrilateral, and triangular, taxonomy bloom

DMS emissions from the Arctic marginal ice zone

Phytoplankton blooms in the Arctic marginal ice zone (MIZ) can be prolific dimethylsulfide (DMS) producers, thereby influencing regional aerosol formation and cloud radiative forcing. Here we describe the distribution of DMS and its precursor dimethylsulfoniopropionate (DMSP) across the Baffin Bay receding ice edge in early summer 2016. Overall, DMS and total DMSP (DMSPt) increased towards warmer waters of Atlantic origin concurrently with more advanced ice-melt and bloom stages. Relatively high DMS and DMSPt (medians of 6.3 and 70 nM, respectively) were observed in the surface layer (0–9 m depth), and very high values (reaching 74 and 524 nM, respectively) at the subsurface biomass maximum (15–30 m depth). Microscopic and pigment analyses indicated that subsurface DMS and DMSPt peaks were associated with Phaeocystis pouchetii, which bloomed in Atlantic-influenced waters and reached unprecedented biomass levels in Baffin Bay. In surface waters, DMS concentrations and DMS:DMSPt ratios were higher in the MIZ (medians of 12 nM and 0.15, respectively) than in fully ice-covered or ice-free conditions, potentially associated with enhanced phytoplanktonic DMSP release and bacterial DMSP cleavage (high dddP:dmdA gene ratios). Mean sea–air DMS fluxes (µmol m–2 d–1) increased from 0.3 in ice-covered waters to 10 in open waters (maximum of 26) owing to concurrent trends in near-surface DMS concentrations and physical drivers of gas exchange. Using remotely sensed sea-ice coverage and a compilation of sea–air DMS flux data, we estimated that the pan-Arctic DMS emission from the MIZ (EDMS, MIZ) was 5–13 Gg S yr–1. North of 80°N, EDMS, MIZ might have increased by around 10 ± 4% yr–1 between 2003 and 2014, likely exceeding open-water emissions in June and July. We conclude that EDMS, MIZ must be taken into account to evaluate plankton-climate feedbacks in the Arctic.

제주 온주밀감 과실의 발육시기별 볼록총채벌레 피해증상

The damage of citrus caused by Scirtothrips dorsalis Hood is increasing in Jeju, Korea. The study about seasonal abundance of S. dorsalis in citrus orchards and occurrence of S. dorsalis in citrus influenced by adjacent primary host orchards has been conducted. However, study of injury symptoms caused by S. dorsalis in citrus is not clear. The symptoms are various according to seasons of occurrence and difficult to distinguish with other similar injury symptoms caused by citrus red mite, broad mite and citrus black spot disease. This study was conducted to distinguish the symptoms according to seasons of fruit stage and utilize for making strategy control S. dorsalis. The symptoms can be divided according to fruit stage. Symptom of full bloom stage was silver-white circle ankertrass around sepal and style of citrus. And symptom of 1st physiological fruit drop stage was that the area of silver-white circle was increased to inside and outside of circle around sepal and style of citrus. The symptom of 2nd physiological fruit drop stage was that the surface of damaged was suberized and cracked and transparent. At enlargement stage, rustic colored fruit was found and the symptom was generalized at coloring fruit stage. This result shows the symptoms caused by S. dorsalis on satsuma mandarin according to fruit stage and can be used as the basic data for studying control of S. dorsalis.

Different response pattern of cyanobacteria at development and maintenance stage to potassium permanganate oxidation

Occurrence of successive cyanobacterial blooms in source waters can continuously impair drinking water quality. Previous studies have separately investigated potassium permanganate (KMnO4) to treat high-viability cyanobacteria at just one stage of either development or maintenance. However, maintenance stage exhibited significantly higher cell-density and extracellular organic matters (EOMs) than development stage, which may result in a different KMnO4 oxidation pattern. In this study, kinetics of oxidant decay, membrane integrity loss, and toxin degradation of high-viability cyanobacteria at both stages were compared. Results showed that cyanobacteria at maintenance stage became more resistant to KMnO4 oxidation than that at development stage, since elevated cell-density and more proteins involved in EOMs resulted in lower oxidant exposure at this stage. Meanwhile, elevated cyanobacterial biomass became the main competitors to decrease toxin degradation efficiency at maintenance stage, leading to incapacity to degrade extracellular toxin to below safety guideline of 1 μg L−1. Consequently, comparing with the best strategy for development stage (6 mg min L−1, no membrane damage), a higher oxidant exposure (12 mg min L−1) was recommended to treat cyanobacteria at maintenance stage even with slight membrane damage (19%), since it degraded extracellular toxin to below safety guideline and achieved the highest removal ratio of EOMs. Overall, this study demonstrated that stage of cyanobacteria can strongly affect KMnO4 oxidation pattern, and it is necessary for water supplies to optimize KMnO4 treatments depending on bloom stage.

Effects of different nitrogen doses and cultivars on fermentation quality and nutritive value of Italian ryegrass (Lolium multiflorum Lam.) silages.

ObjectiveThe fermentation profile and silage quality of 3 Italian ryegrass (Lolium multiflorum Lam.) cultivars (cvs. Devis, Hellen, and Trinova) treated with 5 nitrogen doses (0, 50, 100, 150, and 200 kg/ha) were evaluated.MethodsThe experiment was laid out in split plot in randomized complete block design with three replications. Annual ryegrass cultivars used in this study have been commonly grown in Turkey. Nitrogen doses were set in main plot and cultivars in split plot in the field. Plants were harvested at full-flowering stage with dry matter content about 220 g/kg for first cutting and 260 g/kg for second cutting. Harvested plants were chopped theoretically into 2 to 3 cm lengths for ensiling. Chopped fresh materials were ensilaged by compressing in 2 L plastic jars about 3±0.1 kg.ResultsEffects of N doses on dry matter, neutral detergent fiber, acid detergent fiber, dry matter digestibility, relative feed value, crude protein, pH, ammonia nitrogen, lactic acid, acetic acid, and lactic acid/acetic acid were statistically significant while water soluble carbohydrate, ash and organic matter were not statistically different. Ammonia nitrogen, crude protein, ash, organic matter, lactic acid, and lactic acid/acetic acid were affected by cultivars, but the other parameters were not. Increasing nitrogen applications positively affected the chemical composition of annual ryegrass silage. The significant increase in protein content was remarkable, however, silage fermentation properties were adversely affected by the increasing nitrogen dose.ConclusionIt can be recommended 150 kg/ha nitrogen dose for annual ryegrass harvested at full blooming stage. Even though the silage fermentation properties of the used cultivars were similar, cv. Devis gave better results than the others in terms of silage pH and relative feed value.

Can organic acid and sugar compositions be used to predict cell death point limits? Receptacle and pistil organs of apricot (Prunus armeniaca L.)

To boost our understanding of recent frost damage events in apricot trees, we focused on estimating the cell death point in the receptacle and pistil organs of apricots by simulating the unexpected temperature changes occurring in early spring under laboratory-based freezing experiments. The hypothesis also that organic acids (oxalic, propionic, tartaric, butyric, malonic, malic, lactic, citric, maleic, fumaric and succinic acids) and soluble sugar compositions (glucose, fructose, sucrose and total sugar) may directly stimulate the change of the frost tolerance in apricot receptacle and pistil organs was investigated using two apricot (Prunus armeniaca L.) cultivars, one tolerant to frost (‘Iğdır Şalak’) and the other sensitive to frost (‘Mihralibey’). Our results indicated that the mean the cell death point (CDP) of flower pistil (from −13.26 to −14.18 °C) was at lower temperatures than those of flower receptacle (from −6.28 to −8.65 °C) in both apricot cultivars during the full blooming stage. In both apricot cultivars, receptacle organs showed more sensitive changes to the frost tolerance in response to low temperatures compared with pistil organs. In terms of organic acid and soluble sugar contents, significant differences were determined for both apricot cultivars and between the pistil and the receptacle organs of the flowers. Organic acid content was higher in the freezing-tolerant apricot cultivar (‘Iğdır Şalak’) than the freezing-sensitive apricot cultivar (‘Mihralibey’), but it was lower in the freezing-tolerant organ (pistil) in comparison with the freezing-sensitive organ (receptacle). Moreover, fructose concentrations for both ‘Mihralibey’ and ‘Iğdır Şalak’ were significantly higher in the receptacle compared to the pistil. A significant negative correlation was also observed between the mean CDP values and both all organic acids and sucrose contents in the pistil and the receptacle organs for both apricot cultivars. There was a positive relationship between the CDP values and fructose content in ‘Iğdır Şalak’. Additionally, there was a negative correlation between the CDP values and sucrose in 'Mihralibey'. Overall, the data presented suggest that the high level of sucrose and organic acid content of receptacle and pistil organs contributes to support frost tolerance of organs. The results of this study could help in the understanding of how receptacle and pistil organs of two different apricot cultivars react to frost stress, and how they modulate their soluble sugar and organic acid metabolism.Graphic abstract

Potassium permanganate as a promising pre-oxidant to treat low-viability cyanobacteria and associated removal of cyanotoxins and extracellular organic matters

Cell-viability of cyanobacteria declines from development to decay stage during a successive bloom. Potassium permanganate (KMnO4) has demonstrated to be a superior pre-oxidant to treat high-viability cyanobacteria compared to other common oxidants (e.g., chlorine), but whether it is feasible to treat low-viability cyanobacteria is unknown. Here, effects of KMnO4 on membrane integrity, cyanotoxin fate and extracellular organic matters (EOMs) removal of high- and low-viability cyanobacteria were compared. Results showed that cell-viability of cyanobacteria could affect oxidant decay (kdecay), membrane damage (kloss), and cyanotoxins release (ki) and degradation (ke) during KMnO4 oxidation, similar to chlorination. However, unlike chlorination, initial low dosages of KMnO4 (0.5 and 1 mg L−1) minimized membrane damage for low-viability cyanobacteria (< 27%), and continuously decrease extracellular cyanotoxins, extracellular organic matters (EOMs), and aromatic compounds to some degrees (P<0.05). High dosages of KMnO4 (> 2 mg L−1) caused severe membrane destruction (> 89%) for low-viability cyanobacteria, leading to a fast increase of extracellular cyanotoxins within 1 h. However, total/extracellular cyanotoxins were oxidized to below the safety guideline of 1 μg L−1 after being dosed with sufficient oxidant exposure. EOMs and aromatic compounds were also reduced by 5–18% (P<0.05). Additionally, KMnO4-assisted coagulation significantly improved the removal of low-viability cyanobacteria (2–5 fold). Consequently, KMnO4 could be a promising pre-oxidant to treat low-viability cyanobacteria at decay stage of a successive bloom.

Fungal pathogens of mango (Mangifera indica L.) inflorescences

This is the first comprehensive study to identify fungal pathogens of mango (Mangifera indica L.) inflorescences in Puerto Rico. A total of 452 mango inflorescences were collected from four cultivars at seven developmental stages during two blooming seasons. Samples were gathered from the germplasm collection at the Agricultural Experiment Station of the University of Puerto Rico in Juana Díaz, Puerto Rico. Eight different symptoms were observed: cankers, flower abortion, powdery mildew, rachis necrotic lesions, rachis soft rot, tip blight, vascular wilt, and insect perforations with necrotic borders. Necrosis was the most prevalent symptom (47%), followed by powdery mildew (19%) and tip blight (6%). Symptoms of malformation were never observed in the field. Using a modified Horsfall and Barratt scale, data on all mango cultivars pooled from two blooming seasons showed that the full bloom stage, the last inflorescence developmental stage (G), displayed the highest mean disease severity (42.67%). This severity value was significantly higher than those of the other developmental stages evaluated (P&lt;0.05). Early inflorescence developmental stages were asymptomatic or showed the lowest percentage of disease severity. An ANOVA was performed to compare disease severity among all mango cultivars regardless of developmental stage. Results showed that there were significant differences (P&lt;0.05) between mean disease severity of cultivars ‘Parvin’ and ‘Haden’. Mean disease severity was higher in ‘Haden’ (20%) when compared to ‘Parvin’ (10.7%). There were no statistical differences in mean disease severity between cultivars ‘Irwin’, ‘Keitt’ and ‘Parvin’, or between ‘Irwin’, ‘Haden’ and ‘Keitt’. In addition to the powdery mildew caused by Pseudoidium anacardii, 26 genera of fungi, mainly of Ascomycetes, were identified from a total of 569 fungal isolates, from symptomatic and asymptomatic inflorescences. The most common fungi were: Diaporthe spp. (29%), followed by members of the Botryosphaeriaceae (16%), Curvularia spp. (11%) and Fusarium spp. (11%). Many fungal pathogens identified in this study were isolated from asymptomatic tissue, occurring as endophytes or latent pathogens: A. alternata, various members of the Botryosphaeriaceae, C. gloeosporioides complex, Cladosporium spp. and F. decemcellulare. Thus, the use of protectant fungicides will not be as effective as systemics in their control. Correct identification of fungal pathogens affecting mango inflorescences is important when quarantine regulations are applied. In addition, this information will facilitate the development of better management strategies in mango orchards.

Parasitic activity of plant pathogens at the underground organs of spring wheat in the West Siberia

The purpose of the research was to determine the factors of soil phytopathogens parasitic activity at the underground organs of spring wheat varieties, to clarify the etiology of root rot during the growing season. The studies were carried out in 2020-2021 in the northern forest-steppe of the Ob region (West Siberia) using generally accepted methods. A high parasitic activity of soil phytopathogens was established during the entire growing season of spring wheat: the zonal threshold of harmfulness was exceeded at seedlings up to 2.8 times, at bloom stage to 5 times, and at ripeness stage up to 4 times. The host plants susceptibility to infection with phytopathogens increased during the growing season due to abiotic (drought) and biotic (cereal flies) stresses, which neutralized varietal differences. The main phytopathogens at the underground organs of 20 spring wheat varieties were Bipolaris sorokiniana Sacc. Shom. and Fusarium Link. fungi, the occurrence of which at all underground plant organs (primary roots, secondary roots, stem bases) during the growing season was 100%. The dominance of Fusarium fungi increased during the growing season of plants. The biological diversity of Fusarium fungi was maximal in the bloom phase (up to 7 species on secondary roots of one variety). The species composition of Fusarium fungi was represented by permanent species-F. poae (Peck.) Wollenw. and F. oxysporum Schltdl., additional species-F. sambucinum Fuck., F. graminearum Schwabe and F. equiseti (Corda) Sacc., rare-F. solani Koord., F. sporotrichioides Sherb., F. culmorum Sacc., F. heterosporum Nees., F. acuminatum Ellis & Verh. The succession of Fusarium fungi in the system of plant organs and in the phases of vegetation was revealed, and the parameters of realized ecological niches overlap of Fusarium fungi species were determined.