Organic acid content and composition of the olive fruits during ripening and its relationship with oil and sugar

In this work, the contents of oil, sugar and organic acids of olive fruit samples (Domat, Memecik and Uslu) were determined by using HPLC at different maturation stages. Olive fruit samples presented a common organic acid profile, composed of four constituents: oxalic, citric, malic and succunic acids. Total organic acid content of Domat variety was found to be 4787.1 ± 4.53 mg/100 g in January. Memecik variety had the highest value at the beginning of the ripening period (6385.08 ± 4.90 mg/100 g). The amount of organic acid in Uslu variety reached up to the value of 10942.5 ± 30.41 mg/100 g. The results were evaluated statistically to determine relationship between the oil, sugar and organic acid content in three olive varieties during maturation. A positive correlation was found between the total sugar and organic acid (r = 0.54, p < 0.01) whereas a low positive correlation was observed between the contents of oil and total organic acids (r = 0.46, p < 0.05) in olive varieties.     

Physicochemical changes in Mazafati date fruits incubated in hot acetic acid for accelerated ripening to prevent diseases and decay

A method was developed and optimized for the accelerated ripening of date fruits of cultivar ‘Mazafati’ to prevent diseases and decay. The date fruits were incubated in hot acetic acid solution 0.5% at 40 + 1 °C for 72 h. During the process some physicochemical changes in the fruits were studied and were found to be comparable with the changes in the fruits that naturally ripened on the tree. Fruit firmness, water insoluble solid (WIS), protein, pH, L*a*b* and E decreased during accelerated ripening whereas in control samples at 4 °C increased. Total solid (TS), total soluble solid (TSS) and acidity were slightly higher in treated fruits compared to control fruits. The greatest loss of fruit firmness occurred during the first 12 h of incubation. Organoleptic tests also showed little difference between the naturally ripened fruits on trees and accelerated ripened fruits in hot acetic acid. Overall there was no difference between the fruits and were readily acceptable to consumers.     

The genotypic effects on the chemical composition and antioxidant activity of sea buckthorn (Hippophae rhamnoides L.) berries grown in Turkey

In this study, chemical composition of berries of 10 sea buckthorn (Hippophae rhamnoides L.) genotypes in Turkey was investigated. The total phenolic content of the berries ranged from 21.31 mg gallic acid equivalents (GAE) per g dry weight basis to 55.38 mg GAE per g. The highest antioxidant activity was 93.54% (similar to the standard BHT at 200 mg/L) and the lowest was 80.38%. There was no correlation (R = 0.688) between the total phenolic content and the antioxidant activity. The major fatty acids in berries were palmitoleic acid (35.48%), followed by palmitic acid (28.13%), oleic acid (22.89%) and linoleic acid (3.96%). Total soluble solid content of sea buckthorn genotypes varied from 10.15 to 14.80%, titratable acidity varied from 2.64 to 4.54%, the pH varied from 2.63 to 2.98 and Vitamin C varied from 19 to 121 mg/100 mL. The average content of minerals in the sea buckthorn berries of different genotypes was 20,800 ppm N, 7100 ppm P, 7260 ppm K, 1960 ppm Ca, 1465 ppm Mg, 32 ppm Zn, 24 ppm Cu, 22 ppm Mn and 7 ppm Fe.     

Compositional quality of virgin olive oils from cultivars introduced in Tunisian arid zones in comparison to Chemlali cultivars

This work is an evaluation of the quality of three introduced European olive cultivars Arbequina, Coratina, and Koroneiki grown under a biological agricultural system in the arid zone of Sfax in Tunisia compared to Chemlali cultivars. Various olive parameters were analyzed, such as ripening index, pulp/stone (P/S) ratio and oil content. We have considered the regulated physicochemical analytical parameters, fatty acids and minor compounds for olive oil. The most of the quality indices and fatty acid composition showed significant variations among olive cultivars. The Koroneiki, Coratina and Chemlali Zarzis cultivars had highest values of oleic acid (62.7%) (76.8%, 75.8% and 73.9%, respectively), Arbequina, had lowest value of oleic acid and similar to Chemlali Sfax. Coratina was noteworthy for its higher content of phenolic compounds (287.8 mg kg⁻¹), oil content (42.4%) and P/S ratio (4.7%). Although their low phenol contents, autochthonous cultivars presented high contents of α-tocopherol (577.8 and 434.6 mg kg⁻¹ for Chemlali Boughrara and Chemlali Zarzis, respectively) except for Chemlali Sfax. In conclusion, European cultivars seem to have adapted to the area studied according to their oil biochemical composition while the increase observed in their α-tocopherol levels. The cultivar Arbequina showed a similar composition of Chemlali Sfax.     

Lipid evaluation of cultivated and wild carob (Ceratonia siliqua L.) seed oil growing in Turkey

Studies were carried out on the oil content, fatty acids, tocopherols and sterols in the seeds of two carobs (Ceratonia siliqua), cultivated and wild, from Turkey. The oil yields of cultivated and wild carob seeds were established as 1.73 and 1.82% on a dry weight basis, respectively. The main fatty acids in cultivated and wild carob seed oils are linoleic (49.1% and 51.0%), oleic (30.4% and 26.5%), palmitic (10.3% and 12.0%) and stearic (3.5% and 4.6%), respectively. Tocopherols and phytosterols are important constituents of the unsaponifiable fraction of several seed oils. The major tocopherol in both seed oils was γ-tocopherol. The composition (mg/100 g) was as follows α-tocopherol (69.06 and 70.39 mg/100 g), P8 (22.29 and 24.78 mg/100 g), δ-tocopherol (8.70 and 10.66 mg/100 g), β-tocopherol (2.30 and 1.85 mg/100 g). The total tocopherol contents had 208.45 and 223.14 mg/100 g, respectively. The total content of sterols of both oils were determined as 16400.94 and 30191.55 mg/kg, with β-sitosterol as the predominant sterol that accounted for more than 70% of the total amount of sterols other sterols, campesterol (5.33–5.32%), stigmasterol (0.58–11.43%) 7-avenasterol (3.45–3.03%), 7-stigmasterol (2.16–2.4%), and chlerosterol (1.33–1.0%) were detected in both carob oils. As a result, the accurate quantification of these analyses has very important applications for the nutrition sciences.     

Grafting effects on postharvest ripening and quality of 1-methylcyclopropene-treated muskmelon fruit

In addition to managing soil-borne diseases in muskmelon (Cucumis melo L.) production, grafting with resistant rootstocks may impact fruit quality. The ethylene antagonist 1-methylcyclopropene (1-MCP) has been shown to extend shelf life of fresh muskmelon fruit. Postharvest characteristics of 1-MCP-treated melon fruit as affected by grafting, however, have not been well examined. This study was conducted to explore the influence of grafting with different rootstocks on ripening and quality attributes of 1-MCP-treated muskmelon fruit during postharvest storage. Grafted ‘Athena’ muskmelon with two commercial squash interspecific hybrid rootstocks including ‘Strong Tosa’ and ‘Tetsukabuto’ as well as non-grafted and self-grafted ‘Athena’ were grown in replicated field plots at the University of Florida Plant Science Research and Education Unit (Citra, FL, USA) during April–June 2010. Half-slip fruit from two harvests were treated with 1.0 μL L⁻¹ 1-MCP (18 h, 20 °C) and analyzed during storage at 13 °C. For fruit from the 27 May harvest, whole fruit and mesocarp firmness, titratable acidity, soluble solids, and ascorbic acid content were measured, while production of ethylene and CO₂ was determined on fruit from the 29 June harvest. Grafting did not show a significant impact on fruit yield but affected the fruit shelf life significantly. Fruit from non-grafted ‘Athena’ and ‘Athena’ grafted onto ‘Strong Tosa’ demonstrated a shelf life of 31 d for the first harvest and 22 d for the second harvest. Shelf life of fruit from self-grafted ‘Athena’ and ‘Athena’ grafted onto ‘Tetsukabuto’ declined by 6 d and 3 d for the first and second harvest, respectively. Whole fruit firmness decreased by approximately 15.5% on average from 13 to 31 d except day 19 as a result of grafting, but to a lesser extent with ‘Strong Tosa’ rootstock. Mesocarp firmness of grafted melon was reduced by about 30.2% at days 13 and 19 compared to non-grafted ‘Athena’ fruit. In contrast, titratable acidity, soluble solid content, and ascorbic acid concentration were less affected by grafting. All the measurements except for ethylene and CO₂ production declined during storage regardless of the grafting treatment. Compared with ‘Strong Tosa’ rootstock, ‘Tetsukabuto’ resulted in a more rapid ripening under 1-MCP application, as reflected by earlier increase in ethylene production and higher respiratory rate. The study demonstrates that grafting effects on postharvest ripening and quality of ‘Athena’ muskmelon can vary markedly with rootstocks used.     

Morpho-pomological and chemical characterization of pomegranate (Punica granatum L.) genotypes in Apulia region,Southeastern Italy

A recent increasing demand in Western countries for pomegranate products by consumers is especially supported for the nutritional and medicinal characteristics, due to the antioxidant properties of this fruit. Some studies have been published on the morphological and biochemical characteristics of pomegranate fruits in some Mediterranean countries, but little information is available about the genotypes present in Italy and in particular in Apulia (Southeastern region of Italy). This study (2008–2009) evaluated morpho-pomological and chemical parameters of eight pomegranate genotypes localized in private small orchards. Significant differences were observed among the pomegranate genotypes for many of the parameters investigated. In particular, fruit weight ranged from 168.9 g (SouMol) to 574.9 g (SouOst), °Brix from 14.7 (ComTri) to 18.0 (SouMol), titratable acidity from 5.4 (ComMol) to 25.0 (SouTri) g/L. SouMol showed the highest polyphenols (97.1 mg/L) and vitamin C (236.3 mg/L) contents. Oil content of the seeds was between 5.90% and 10.30%, no differences have been observed for the fatty acid composition with conjugated linoleic acid (CLA) isomers as the most abundant fraction (81.23%). Considering all the evaluated parameters, and especially those referring to the organoleptic characteristics and antioxidants content, it must be stated that the best genotypes worthy to be considered from agricultural and industrial points of view were AdeSgi for fresh market and SouOst for the juice industry.     

Phenolic content and free radical scavenging activities in rambutan during fruit maturation

The 1,1-diphenyl-2-picrylhydrazyl (DPPH^•) scavenging activity, changes and accumulation of phenolic content were studied in the peel, seed and pulp of rambutan, Nephelium lappaceum L. (Rongrien and Seeechompoo cultivars) during fruit maturation. The IC₅₀ values of the radical scavenging activity of the peels, in both cultivars remained low through fruit development (1.42–4.75 μg/mL) but the values of the seed and pulps were low at the beginning and increased markedly toward fruit development until harvest (4.87 to >1000 μg/mL). The accumulation of phenolic compounds in rambutan peels of Rongrien and Seechompoo cultivars increased continuously until reaching a maximum of 1653 and 733 mg per fruit at the time of being harvested, at 112 and 98 days after full bloom (DAFB), respectively. Ellagic acid, corilagin and geraniin in the peels of both cultivars were observed and quantified. The major component in the peels of the two cultivars was geraniin. The accumulation of ellagic acid, corilagin and geraniin in the peels increased and reached the maximum at the harvest stage, especially the major constituent of geraniin (1011 and 444 mg/fruit for Rongrien and Seechompoo, respectively). The free radical scavenging property was observed to have a relationship with the phenolic content quantified in different parts of the rambutan fruit. This research demonstrates potential data on phenolic constituents through fruit development, especially in the peels at the time of harvest.     

Changes in antioxidants and fruit quality in hot water-treated ‘Hom Thong’ banana fruit during storage

The effects of hot water treatment on antioxidants and fruit quality were investigated in banana fruit of cv. Gros Michel (Musa acuminata, AAA Group, locally called cv. Hom Thong) by immersing fruits in hot water (50 °C) for 10 min, before storage at 25 °C for 10 days or 14 °C for the first 8 days followed by storage at 25 °C for the second 8 days until ripening. Quality parameters including peel color and pulp firmness indicated that hot water treatment helped to delay banana fruit ripening at both storage conditions. Hot water treatment decreased the levels of hydrogen peroxide (H₂O₂) and malonydialdehyde (MDA) during storage at 25 °C. Glutathione (GSH and GSSG) contents and the ratio of GSH/GSSG during fruit approaching ripening were significantly induced in hot water-treated fruits while ascorbic acid (AA) contents were slightly increased. In addition, the combined treatment increased free phenolics and flavonoids during storage. Results suggest that hot water treatment has led to an induction of antioxidants in banana fruits as indicated by an increase of antioxidants and a decrease of H₂O₂ during ripening, and all of which result in a delayed ripening of banana fruit.     

Fractional changes of pectic polysaccharides in different tissue zones of developing guava (Psidium guajava L.) fruits

Cell-wall pectic polysaccharides were fractionated by sequential extraction with water, 1% potassium oxalate at room temperature, 0.05 M HCl at 100 °C and 0.05 M NaOH at 4 °C from the three specific tissue zones, i.e., outer pericarp (OP), middle pericarp (MP) and inner pericarp (IP) of the guava fruits during their development and ripening. The water and oxalate-soluble pectic fractions were found to increase, while acid and alkali-soluble pectic fractions had a decreasing trend at ripening phase of fruit, irrespective of the different tissue zones. However, the extent of pectic solubilization was more pronounced in IP region as compared to OP and MP zone of the fruit tissue. The differential degradation of pectic polymers thus points out that ripening as well as tissue softening of guava fruits are centrifugally expressed as evidenced by higher accumulation of sugar and soluble pectic polysaccharides in IP zone of the fruits.     

Water deficit effects on Salvia officinalis fatty acids and essential oils composition

The effects of water deficit on vegetative growth, fatty acids and essential oil yield and composition of Salvia officinalis aerial parts were investigated. Plants were treated with different levels of water deficit (C, MWD and SWD). Results showed important reductions of the different growth parameters. Drought decreased significantly the foliar fatty acid content and the double bond index (DBI) degree. This later was provoked mainly by a strong reduction of linolenic acid proportion and the disappearance of palmitoleic acid. Besides, moderate deficit increased the essential oil yield (expressed as g/100 g on the basis of dry weight) and the main essential oil constituents were camphor, α-thujone and 1.8-cineole which showed an increasing under moderate water deficit.     

Biocontrol of mildew with Bacillus subtilis in bitter gourd (Momordica charantia L.) seeds during germination

The bitter gourd seed has a thick, hard seed coat. Mildew often occurs during germination and causes uneven and low rates of seed germination. However, the problems caused by mildew can be overcome by treating seeds with hot water, by soaking in water, or by using microorganisms. Seeds of the ‘Ching Pi’ bitter gourd were treated in a water bath at 60 °C for 10 min and then soaked in tap water at 25 °C for 24 h. The resulting germination percentage was 86.7%, and the resulting percentage of mildewed seeds was 10%. The biocontrol potential of three commercially available Bacillus subtilis solutions was examined. For seeds primed with Huodijun B. subtilis solution, the germination percentage was 73.3% and the mildewed percentage 6%. In dual cultures, the antibiotic content in the Huodijun B. subtilis solution was significantly greater than in Yunghsing and Huolibao, the other B. subtilis solutions examined. B. subtilis effectively inhibited the growth of Rhizoctonia solani mycelium and caused abnormal mycelial growth.     

The effect of size and quality of potato microtubers on quality of seed potatoes in the cultivar ‘Superior’

Potato microtubers produced in vitro of the cultivar ‘Superior’ were assessed to decide up to what size it can be used for the seed potato with respect to storability, dormancy period, and sprouting vigor. The larger microtubers lost moisture content more slowly and retained firmness longer when stored at 4 °C. In the sprouting test, the larger ones had less period of dormancy and showed more vigorous sprouting ability. The starch increased with increasing size of the microtuber and showed the distribution of about 70–80% of dry matter content. The amounts of sugars were positively co-related with the size of the potato. The internal factors such as dry matter and carbohydrate content reveal that potato microtuber follows the field-grown potatoes in all aspects. The results suggest that the size of microtubers can be used as an index for grading their quality as seed potatoes, and the size of the microtuber should be at least 0.5 g to be used as seed potato.     

Amelioration of chilling stress by paclobutrazol in watermelon seedlings

Paclobutrazol (PBZ) is a member of the triazole plant-growth inhibitor group that is responsible for inducing tolerance to number of biotic and abiotic stresses. An experiment was, therefore, conducted to test whether PBZ application at various concentrations (0, 25, 50 and 75 mg L⁻¹) through seed soaking or foliar spray would protect watermelon (Citrullus lanatus) seedlings, subjected to chilling stress. Thirty-five-day old plants were exposed to chilling 5 h/day at 4 °C for 5 days. PBZ improved growth rate of watermelon seedling subjected to chilling stress and increased relative leaf chlorophyll content (RLCC) and chlorophyll fluorescence ratio (Fv/Fm) compared with the control at the end of chilling stress. PBZ ameliorated the injury caused by chilling stress by inhibiting increases in proline and leaf electrolyte leakage, which suggested that PBZ ameliorated the negative effect of chilling stress. PBZ was most effective in increased chilling tolerance of watermelon seedling when applied using the seed soak method than as a foliar spray. The best protection appeared to be obtained from seedlings seed soaked with PBZ at 50 and 75 mg L⁻¹.     

Application method and rate of Trichoderma species as a biological control against Pythium aphanidermatum (Edson) Fitzp. in the production of microgreen table beets (Beta vulgaris L.)

Seed balls of ‘Early Wonder Tall Top’ table beet (Beta vulgaris L.) were incubated for 2 days at 21 °C in moist exfoliated grade 3 vermiculite (3 g seed balls [168 seed balls] and 1.1 g vermiculite) containing equal weights of Trichoderma harzianum Rifai strain KRL-AG2 G41 and T. virens strain G-41 (ThTv) at 0, 0.25, 0.50, 0.75 or 1.00 mg ThTv per seed ball. ThTv also was applied to the peat-lite growth medium 14 days before planting, at the same rates per seed ball as the seed ball treatments. Four days before planting, the peat-lite was inoculated with Pythium aphanidermatum (Edson) Fitzp. (Pa) at 0, 0.5 and 1.0× the rate that resulted in 96% damping-off when non-ThTv-treated dry seed balls were sown in peat-lite containing 1.0 Pa. Increasing ThTv level per seed ball decreased percentage damping-off, with 1.0 Pa giving greater percentage damping-off than 0.5 Pa. At 1 mg ThTv per seed ball, damping-off was 5% and 19% at 0.5 and 1.0 Pa, respectively. Including Agro-Lig UF (mostly humic acids) in the incubating seed-ball-ThTv mixture further decreased damping-off by an average 13 and 10 percentage points in 0.5 and 1.0 Pa, respectively. Increasing ThTv per seed ball in growth media decreased percentage damping-off, but not to the extent achieved with seed ball treatment, with 1 mg ThTv per seed ball giving 20% and 55% damping-off in 0.5 and 1.0 Pa, respectively. Decreasing incidence of damping-off with increasing ThTv application to seed balls or growth media was associated with increasing shoot fresh weight m⁻² at 14 days after planting, a response attributable to increased percentage plant survival and not to a ThTv growth-promoting effect.     

Effect of hot acetic acid solutions on postharvest decay caused by Penicillium expansum on Red Delicious apples

The objective of this research was improvement of apple hot water treatment efficiency by using acetic acid. The apples (cultivar Red Delicious) were treated using hot acetic acid solutions (1, 2 and 3%) at 50 °C for 1, 2 and 3 min. The results of in vitro study showed that treatment with acetic acid at 50 °C can significantly reduce the growth of Penicillium expansum spores. The treatment of apples with 50 °C acetic acid solutions, in particular 2% acetic acid solution for 3 min or 3% acetic acid solution for 2 min, had significant impacts in reducing the extent of decay of the fruit during the short time storage experiment, while this effect was not significant in the long-time storage.     

Cold storage of oil rose (Rosa damascena Mill.) flowers

Oil rose flowers were stored at 0 °C in four different packaging materials [plastic box + stretch film (PB + SF), Xtend^®, Smartbag^® and polyethylene (PE)] for 60 days. During storage, weight loss, O₂ and CO₂ concentrations in the packages, petal color and sensorial attributes were investigated besides essential oil content and composition. Storage duration and packages had significant (p < 0.01) effects on weight loss. At the end of storage, the lowest weight loss was in PE package (1.696%) whereas the highest weight loss was in Xtend^® (10.081%). The essential oil content was significantly (p < 0.01) affected by storage duration and packages. In addition, the essential oil contents obtained from all packages for a storage period of 10 days and the essential oil contents obtained from unstored (control) petals were included in the same group. At the end of storage, the essential oil contents decreased by 91.3, 57.7, 80.0 and 64.3% in PB + SF, Xtend^®, Smartbag^® and PE packages, respectively as compared to control. In addition, storage duration and package types significantly (p < 0.01) affected petal color, O₂ and CO₂ concentrations in the packages and sensorial scores. The concentration of citronellol, a main component of rose oil, increased in all packages during storage of 10 days in comparison to the control group while it varied in other storage durations and package types. However, nerol and geraniol were lower than the control group during storage while concentrations of nonadecane, heneicosane and eicosane were higher. In conclusion, loss of oil yield and quality, due to various reasons and particularly due to fermentation in oil rose from the harvest of petals to their distillation, can be minimized with storage of petals in all package types for up to 10 days.     

Influence of harvest time and after-ripening on the seed quality of eggplant

Eggplant cv. Emi and Tsakoniki were cultivated for seed in an unheated greenhouse and fruits were harvested at 25–65 days after anthesis (DAA) in order to determine the optimum harvest time. In addition, the effect of after-ripening on seed quality (i.e. seed size and germination) was examined by storing harvested fruit at 25 °C for 20 days prior to seed extraction. From the results, it was concluded that the optimum time of harvest for seed production is 55 DAA. Seeds extracted from fruits that were harvested at 25–35 DAA did not germinate, but when fruits harvested at the same age were stored for 20 days at 25 °C prior to seed extraction (i.e. seeds were after-ripened) germination was induced. Seeds extracted from fruits harvested at 45 DAA showed a high percent germination, which decreased after storage at 25 °C for 3 months. This decrease, however, was reduced by after-ripening prior to extraction. It is concluded that although eggplant is a non-climacteric species and fruit do not ripen after harvest, nevertheless seeds within the fruit continue to fill and mature after harvest; hence storage of prematurely harvested fruit prior to seed extraction permits the seeds of these fruits to after-ripen in situ and thereby increases seed size and germination. The implication of this result for eggplant seed production is discussed.     

Promotion by 5-aminolevulenic acid of pepper seed germination and seedling emergence under low-temperature stress

The effects of incorporating 5-aminolevulenic acid (ALA) into the priming solution on low-temperature germination and emergence percentage performance of red pepper (Capsicum annuum cv. Sena) seeds before and after seed storage were investigated. Seeds were primed in 3% KNO₃ solution for 6 days at 25 °C in darkness containing 0 ppm, 1 ppm, 10 ppm, 25 ppm, 50 ppm or 100 ppm ALA. Following priming, seeds were either immediately subjected to germination and emergence tests at 15 °C or stored at 4 °C or 25 °C for 1 month after which they were subjected to germination and emergence tests at 15 °C. Priming pepper seeds in the presence of ALA improved final germination percentage (FGP) and germination rate (MGT) at 15 °C compared to non-primed seeds. The highest FGP was obtained from seeds primed in the presence of 25 ppm and higher ALA concentrations while the highest MGT was obtained from seeds primed in KNO₃ supplemented with 10 ppm ALA. Emergence percentages were the highest for the seeds primed in the presence of 25 ppm ALA and 50 ppm ALA while non-primed seeds had the lowest emergence percentage. Highest emergence rates (MET) and heaviest seedlings were also obtained from seeds primed in KNO₃ supplemented with 50 ppm ALA. Although all priming treatments improved germination and emergence performance of pepper seeds at 15 °C following 1 month of storage under two different temperatures, inclusion of 25 ppm and 50 ppm ALA into the priming solution resulted in higher germination and emergence percentages and faster germination and emergence compared to seeds primed in KNO₃ only and non-primed seeds. These results indicate that priming seeds in 25 ppm and 50 ppm ALA incorporated into the KNO₃ solution can be used as an effective method to improve low-temperature performance of red pepper seeds and that these seeds can be stored for 1 month at 4 °C or 25 °C and still exhibit improved germination and emergence performance at 15 °C.     

Can a post-harvest ripening treatment extend the longevity of Rhododendron L. seeds?

Pre-dehiscent capsules were collected from two Rhododendron griersonianum (Balf.f. & Forrest) trees and either immediately dried in a dry-room (15% relative humidity, 15 °C) or placed in a high humidity room (80% relative humidity, 15 °C) for 30, 60, or 90 d. Further capsules were also collected from the trees at 30 and 60 d, but seeds had been dispersed by 90 d. Seed ageing experiments (60% relative humidity, 45 °C) carried out on these seed-lots and on seeds from a further 10 Rhododendron (L.) species confirmed that short seed lifespans is a trait of the genus, with a mean P₅₀ value of ca. 20 d for this storage environment.