Freezing temperature treatment induces bud dormancy in ‘Granny Smith’ apple shoots

One-year-old, ‘Granny Smith’ apple (Malus × domestica Borkh.) shoots were selected randomly from commercial orchards in 1999 and 2003, cold stored at temperatures between 1 and 13 °C for varied periods, following a 12/12 h freezing temperature pre-treatment of −1/13 °C (supposedly non-chilling temperatures) for 1 or 2 weeks. The rate of budburst, determined after forcing at 25 °C, was used to follow the progression of bud dormancy. The freezing pre-treatment clearly enhanced (deepened) bud dormancy in all experiments. Clearly definable influences due to the presence of leaves during the pre-treatment were not observed on shoots cold stored at chilling temperatures. Trees were defoliated before leaf drop in late summer/autumn under field conditions by hand (2001) and using a spray containing 3% urea and 1.8% zinc sulphate in 2003. In 2001 the first two hand defoliation dates significantly enhanced dormancy, while in 2003 chemical defoliation had no effect. These data indicate that the leaves are not clearly involved in the perception of factors that are responsible for dormancy induction. As with dormancy release it is possible that the perception of induction factors, i.e. low temperatures, and as shown in these data, freezing temperatures, occurs within the buds themselves.     

Day and night temperatures,daily light integral,and CO2 enrichment affect growth and flower development of Campanula carpatica ‘Blue Clips’

Campanula carpatica Jacq. ‘Blue Clips’ plants were grown in a greenhouse under nine combinations of day and night temperatures created by moving plants every 12 h among three day/night temperatures (15, 20, and 25°C). At each temperature, there were three daily light integrals (DLI; 4.2, 10.8, and 15.8 mol m⁻² per day, averaged over the experimental period) created with varying supplemental light, and ambient (≈400 μmol mol⁻¹) and enriched (≈600 μmol mol⁻¹) CO₂ concentrations. Time to flower was closely related to average daily temperature (ADT), and was not significantly affected by the day or night temperatures delivered to achieve a specific ADT. Time to flower was not largely affected by DLI or CO₂ enrichment. As plant ADT increased between 15 and 25°C, flower diameter decreased about 1 mm per degree and was not related to the difference between day and night temperatures (DIF). Flower diameter was smallest and least sensitive to changes in temperature at lower DLI and at ambient CO₂ levels. There were 10 less flower buds and 0.3 g less dry mass per plant at first flower for every 1° increase in plant ADT at high and medium DLIs. Flower bud number and dry mass were relatively low and less sensitive to changes in ADT at low DLI, and increased slightly with CO₂ enrichment at medium and high but not at low DLI. Plant height was not related to ADT, but increased linearly as DIF increased from −6 to 12°C at all DLIs, but the response was stronger under low DLI than high and medium DLIs. Flower bud number and dry mass were correlated closely with the ratio of DLI to daily thermal time (base temperature of 0°C). Flower bud number and dry mass were highest when C. carpatica plants were grown at 15°C with a DLI of 10–15 mol m⁻² per day.     

Flowering of Primula malacoides in response to photoperiod and temperature

Primula malacoides Franch. ‘Prima Lilac’ was grown at 16 or 20 °C in combination with short days (SD, 8 h) or long days (LD, 16 h). In addition to uninterrupted growing conditions, plants within each temperature were moved at weekly intervals to the other photoperiod and left until termination. Temperature, but not photoperiod, significantly affected the rate of development from start of treatments (51 days from seeding) to 2 mm visible flower bud (VB). At 16 °C, VB averaged 30 days and at 20 °C, 48 days. Time to flower (first horizontal petals) at 16 °C increased from 56 to 64 days as SD increased from 1 week to continuous conditions while LD decreased time to flower from 64 to 56 days. Time to flower at 20 °C varied from 73 to 87 days with additional SD exposure resulting in slower and LD in faster flowering. These observations of the flowering response in ‘Prima’ are contrary to the photoperiodic classification of P. malacoides as a SD plant.     

Temperature effects on flower formation in saffron (Crocus sativus L.)

The temperature conditions for shoot growth and flower formation were characterised for saffron (Crocus sativus L.). Leaf withering occurred during late winter or spring depending on location, and coincided with a rise in temperature. No growth was detectable in the buds during the first 30 days after leaf withering, neither in underground corms nor in lifted corms incubated in the laboratory under controlled conditions. Flower initiation occurred during the first growth stages of the buds. The optimal temperature for flower formation was in the range from 23 to 27 °C, 23 °C temperature being marginally better. To ensure the formation of a maximum number of flowers, the incubation at these temperatures should exceed 50 days, although incubation longer than 150 days resulted in flower abortion. Flower emergence required the transfer of the corms from the conditions of flower formation to a markedly lower temperature (17 °C). Incubation of the corms after lifting at a higher temperature (30 °C), reduced flower initiation and caused the abortion of some of the initiated flowers. No flowers formed in corms incubated at 9 °C. A variable proportion (20–100%) of the corms forced directly at 17 °C without a previous incubation at 23–27 °C formed a single flower. The wide differences in the timing of the phenological stages in different locations we found in this study seemed related to the ambient temperature. Leaf withering was followed shortly by flower initiation, which occurred during late spring or early summer as the rising temperature reached 20 °C. A long hot summer delayed flower emergence which occurred in late autumn as the temperature fell to the range of 15–17 °C.     

Temperature and irradiance effects on Sandersonia aurantiaca flower shape and pedicel length

Sandersonia flowers can vary from being lantern- to tubular-shaped. Lantern-shaped flowers are considered to be most commercially desirable when the ratio of the widest to the narrowest diameters of a flower, termed the ratio of hips to waist, is 1.5 or greater. Pedicel length can also affect the overall appearance of a flower stem. Short pedicels are considered more desirable. The influences of temperature and irradiance on Sandersonia aurantiaca flower shape and pedicel length were examined in controlled environment (CE) growth rooms. The growing environments were at constant temperatures of 15, 18, 21, 24 or 27 °C; or day/night temperature differentials of −6, 0, +6, +12, or +18 °C, with a mean of 21 °C. Photosynthetic photon flux densities (PPFD) were 700, 460 or 210 μmol m⁻² s⁻¹. At harvest, measurements were made of the widest and narrowest diameters of the oldest flower on each stem and the ratio of these parts was calculated. The pedicel length of the oldest flower was also measured. Environments with constant temperatures below 23 °C and the least day/night temperature differentials (−6, 0 and +6 °C) produced flowers of the most desirable shape, defined as having a hips to waist ratio of 1.5 or greater. At these temperatures, irradiance had a variable effect on flower shape. Pedicel length was also highly dependent on temperature and PPFD. As mean temperatures increased or as the temperature differential changed towards a differential of 12 °C, and as PPFD decreased, pedicel length increased significantly. Hip diameter was more sensitive to environmental changes than waist diameter and thus had a greater effect on flower shape. This work indicates to growers that they can enhance Sandersonia flower quality by producing more desirably shaped flowers with short pedicels through maintaining relatively low (less than 23 °C) mean temperatures, minimising temperature differentials, and maintaining irradiance levels as high as possible.     

Influence of temperature and bark injuries on the development of Phytophthora cactorum and P. Citrophthora on peach trees

The effect of temperature and bark injuries on the occurrence of crown rot of peach trees caused by P. cactorum and P. citrophthora were examined in field and laboratory. Lesions developed at 35 °C (the complete range of temperatures tested) but maximum development occurred at 20–25 °C. Greatest growth of these fungi on cornmeal agar (CMA) also occurred between 15 and 30 °C. Both pathogens could infect injured trees up to 20 days after wounding, but could not infect uninjured plants or plants wounded 40 and 30 days before inoculation, respectively. This study showed that temperature is a critical factor for the development of Phytophthora crown rot of peach trees. In addition, crown rot developed from recent wounds inoculated with agar plugs of Phytophthora.     

Bruising injury of persimmon (Diospyros kaki cv. Fuyu) fruits

This study was performed to monitor the deterioration of bruised persimmon (Diospyros kaki cv. Fuyu) fruits. Freshly harvested fruits were bruised by dropping them from a height of 50 cm onto a steel board and then stored at 0 or 20 °C in temperature controlled chambers for up to 4 weeks. Immediately after the bruising, no visible injury on the fruits was evident, but the fruits deteriorated rapidly during storage. The skin tissues of the fruits stored at 20 °C became more reddish with the duration of the storage, but no such changes were found with the fruits stored at 0 °C. The increase in redness of the skin tissues appeared to be associated with storage temperature, but not with the bruising. The skin tissues also became darker when stored at 20 °C than at 0 °C and this tendency was more obvious with the bruised fruits. Flesh firmness decreased rapidly during storage except for the non-bruised fruits stored at 0 °C. Even the non-bruised fruits rapidly lost their flesh firmness at 20 °C. No significant changes in lipid peroxidation, as expressed by malondialdehyde production, were found between the bruised and the non-bruised fruits during the storage either at 0 °C or at 20 °C. This implies that the fruit deterioration caused by bruising is not due to the consequences of lipid peroxidation. Polyphenol oxidase activity increased more rapidly in the bruised fruits than in the non-bruised fruits during storage. The bruising had more effect on increasing polyphenol oxidase activity than did the storage temperature. Although the increase in polyphenol oxidase activity appeared to be associated with the visual deterioration of the bruised fruits, it did not exactly correspond to the physical deterioration. These results indicate that polyphenol oxidase is not the only factor influencing the deterioration associated with bruising. Cell wall hydrolases are currently being assayed to determine if they also contribute the deterioration following bruising.     

Effect of temperature on seed and fruit development in three mango (Mangifera indica L.) cultivars

The effect of diurnal maximum/minimum (20/10 or 25/15 °C) temperatures on seed and fruit development of ‘Irwin’, ‘Kensington’ and ‘Nam Dok Mai’ mangoes (Mangifera indica L.) was studied in a controlled-environment glasshouse. Exposure to low temperatures (20/10 °C day/night) 3 days after hand pollination significantly increased the percentage of stenospermocarpic fruit (nubbins), in which embryos were aborted at some stage during early fruit development. There were significant differences between cultivars in the percentage of nubbins produced out of the total fruit set following overnight exposure to 10 °C with 21% for ‘Nam Dok Mai’, 11% for ‘Kensington’ and 3% for ‘Irwin’. At 45 days after pollination, nubbin fruits were much smaller in size and weighed ca. 50% less than normal fruits. The lower percentage of nubbin fruits in ‘Irwin’ implies a greater adaptation to cool temperatures by this cultivar during fruit set and early embryo development.     

Decreased anthocyanin biosynthesis in grape berries grown under elevated night temperature condition

In grape cultivation, high night temperature generally reduces anthocyanin accumulation in berry skin. To clarify the regulatory mechanism of anthocyanin biosynthesis under the conditions of high night temperatures, we examined flavonoid accumulation, the activities of related enzymes and gene expression in the anthocyanin biosynthetic pathway in grape berries grown under cool and warm night conditions. Anthocyanin accumulation in the skin of berries grown at high night temperatures (30 °C continuous) was reduced as compared to that of berries grown at low night temperatures (30 °C in daytime/15 °C in night time). On the other hand, flavonol levels in the skin of berries were not significantly different between low and high night temperature conditions. High night temperatures also inhibited the gene expression of chalcone synthase (CHS), flavanone 3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), leucoanthocyanidin dioxygenase (LDOX) and UDP-glucose: flavonoid 3-O-glucosyltransferase (UFGT) at veraison and an increase in UFGT activity after veraison. These results suggest that the inhibition of anthocyanin biosynthesis in grape berries grown under high night temperature condition could be caused by lower expression levels of anthocyanin biosynthetic genes at an early stage of ripening and lower activities of anthocyanin biosynthetic enzymes, particularly UFGT.     

In vitro production of Prunus necrotic ringspot virus-free begonias through chemo- and thermotherapy

Prunus necrotic ringspot virus (PNRSV)-free Begonia spp. plants were raised from petioles of virus-infected plants using in vitro techniques. The petioles were grown on MS medium supplemented with 0.2 mg/l NAA and 0.2 mg/l BAP (pH 5.8). For rooting, half-strength MS medium without any plant growth regulators was used. On rooting medium, shoots were subjected to chemotherapy (virazole, 2-thiouracil or 6-azauracil) and thermotherapy (38 °C for 16 h light period and 22 °C for 8 h dark period) separately or in combination. Regenerated plants (treated with chemo- and thermotherapy) were indexed for PNRSV by DAS-ELISA and RT-PCR. An amplified product of 785 bp was obtained by RT-PCR in PNRSV-infected plants. Virazole at a concentration of 20 mg/l was found to be more effective (30 and 20% of PNRSV-free plants as indexed by ELISA and RT-PCR, respectively) in comparison to the other chemicals. Thermotherapy for 25 days gave 35 and 25% PNRSV-free plants as indexed by DAS-ELISA and RT-PCR, respectively. A combination of both treatments gave a good number of PNRSV-free plants (67.5 and 57.5% as indexed by DAS-ELISA and RT-PCR, respectively). At higher concentrations all three chemicals were found to be toxic. Thermotherapy for more than 25 days caused browning of leaves and shoots died.     

Interaction of temperature and vegetative flush maturity influences shoot structure and development of lychee (Litchi chinensis Sonn.)

Potted lychee trees (cv. Tai so) of varying vegetative flush maturity were grown under a range of temperature regimes and monitored for subsequent shoot structure and development. A combination of low temperature (15/17 or 18/13 °C day/night) and high vegetative flush maturity was necessary for floral initiation to occur. Exposure to high temperatures (28/23 °C) invariably resulted in the production of vegetative shoots, irrespective of flush maturity. Strong floral initiation was marked by the emergence of terminal panicles and accompanying axillary panicles. A decrease in vegetative flush maturity or increase in temperature (e.g. 23/18 °C) resulted in a decrease in axillary shoot formation and the production of several intermediate shoot structures. These included leafy panicles, stunted panicles, partially emerged buds and non-emergent swollen buds, often produced on the same tree. At 23/18 °C, closer synchronisation of initial flush maturity was required for the production of a consistent shoot-type. Trees with synchronised mature flushes (I-2) at 23/18 °C resulted in the production of swollen terminal buds. Healthy trees were maintained in this state for at least 11 months. These results indicate that both temperature and flush maturity can influence subsequent shoot structure of lychee. In the absence of either a strong floral temperature (18/13 °C) or strong vegetative temperature (28/23 °C), slight differences in initial flush maturity have greater impact on the type of emerging shoot formed.     

Production of high quality Ardisia plants by stem tip cuttings

To produce commercially acceptable Ardisia plants, stem tip cuttings from mature plants were rooted and forced in greenhouses. Ten centimeter long cuttings were either treated with 200 ppm 1-naphthalene acetic acid (NAA) for 2 h, 2000 ppm indole-3-yl-butyric acid (IBA) for 10 s, or 0.5 and 1.0% IBA powder prior to sticking them in the rooting medium. Rooting percentage at 45 days exceeded 76% with 2000 ppm IBA treatment which was a significant increase over non-treated control. Rooted cuttings developed into three types of plants: those forming only vegetative shoots without flowers, those forming reproductive shoots with flowers, and those forming both vegetative and reproductive shoots. The ideal plant produced only vegetative shoots when rooted cuttings were transplanted into pots. About 50% rooted cuttings were forced to finish, producing 31 or 40% of high quality plants when rooted cuttings with vegetative shoots were grown in a greenhouse (GH) at temperatures higher than 21/19 °C (day/night) in 1995 or 21/18 °C GH in 1997, respectively. This method shortened the total production time to less than 2 years as compared to 4 years when starting from seeds.     

Partial vacuum extends the longevity of primed bitter gourd seeds by enhancing their anti-oxidative activities during storage

This study evaluates the effects of partial vacuum storage on longevity and anti-oxidative responses of primed bitter gourd (Momordica charantia L.) seeds. Priming was achieved by mixing the seeds with moist vermiculite 25 °C for 36 h, followed by air-drying to the original moisture level. Primed seeds were vacuum-packed and stored at 25 °C for up to 12 months. Priming improved seed germination, reduced lipid peroxidation and enhanced anti-oxidative activity prior to storage. However, primed seeds accumulated more total peroxide than non-primed control after 12 months non-vacuum storage, and this led to a marked decrease in seed longevity. Increased total peroxide levels were associated with decreased percentage of 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical inhibition. Partial vacuum storage proved useful in extending the longevity of primed seeds for up to 12 months. Improved longevity was related to enhanced anti-oxidative activity that minimized the accumulation of total peroxide during long-term storage.     

Environmental factors affecting flowering of rice flower (Ozothamnus diosmifolius,Vent.)

Rice flower (Ozothamnus diosmifolius, Vent.), native to east Australia, is a spring flowering perennial shrub. It is a new cut flower plant, recently introduced into cultivation in Australia and in Israel. Its response to environmental conditions, which affect growth and flowering, are not yet known. The purpose of the present study was to evaluate the effects of growth temperature, photoperiod and total solar energy on flowering. Experiments were conducted with plants of the cv. Cook’s Snow White. Plants were grown in three cycles under controlled conditions in the phytotron, at four day/night temperature regimes: 17/9, 20/12, 23/15 and 26/18°C. Two photoperiods — short day (SD) of 10 h natural day light and long day (LD) of 10 h natural light plus 10 h incandescent light — were employed. High temperatures enhanced vegetative growth but blocked flowering under both LD and SD. Under medium–moderate temperatures plants were absolute LD plants and did not flower under SD conditions. Under lower temperatures plants flowered under both LD and SD, but SD delayed flowering. High total solar radiation under LD did not affect flowering time but greatly promoted the number of flowering stems.     

Chilling induced ethylene biosynthesis in ‘Hayward’ kiwifruit following storage

‘Hayward’ kiwifruit were stored at 0, 5, 10, 15 and 20°C for 5, 12 and 17 days before rewarming to 20°C for 10 more days. Ethylene and CO₂ production, ACC, ACC synthase (ACS) and ACC oxidase (ACO) activities, flesh and core firmness, soluble solids content (SSC) and flesh colour were measured. Kiwifruit stored at 0, 5, 10 and 15°C did not ripen, produce ethylene or show increases in ACS or ACO activity. Fruit stored for 5 days at the above temperatures, then rewarmed to 20°C, did not show any change during the following 10 days. Rewarmed fruit, pre-stored at 0–10°C for 12 days, started autocatalytic ethylene production within 24 h, followed by fruit ripening. Fruit stored at 15°C for 12 days needed 72 h to start ethylene autocatalyse and did not fully ripen during 10 days at 20°C. After 17 days storage at 0–15°C kiwifruit started autocatalytic ethylene production with no delay upon exposure to 20°C. Autocatalytic ethylene production correlated with increased ACC content, and increased activities of ACS and ACO. Fruit held continuously at 20°C started autocatalytic ethylene production after 19 days, with concomitant increases in ACC content, ACS and ACO activities and ripening. Respiration increased after rewarming, concomitantly with the increase in ethylene production.We concluded that exposing kiwifruit to chilling temperatures (0–10°C) for 12 days advanced ethylene biosynthesis and ripening when compared with fruit held continuously at 20°C. The advanced ethylene biosynthesis was due to increase ACS and ACO activities immediately upon rewarming of the fruit.     

Effects of cold storage on postharvest leaf and flower quality of potted Oriental-, Asiatic- and LA-hybrid lily cultivars

The effects of cold storage of mature potted plants on postharvest leaf and flower quality were investigated in several cultivars of three major groups (Oriental, Asiatic and LA) of hybrid lilies (Lilium spp.). Mature plants were stored in darkness at 3 °C for 2 weeks before placing them in a postharvest evaluation room (22 °C) and were compared with plants moved directly to the evaluation room. The efficacy of GA₄₊₇ plus benzyladenine (BA) treatments (applied just before cold storage) for preventing cold-induced postharvest disorders in each cultivar was also evaluated. In all cultivars, cold storage caused several adverse effects on postharvest quality, including accelerated leaf yellowing or browning, bud abortion and reduced flower or inflorescence longevity. Leaf abscission was observed only in Oriental-hybrids. Treatment with GA₄₊₇ plus BA significantly reduced these disorders and improved the overall postharvest quality after cold storage. While different cultivars differed greatly in their sensitivity to cold storage, all the cultivars benefited from GA₄₊₇ plus BA treatment. Experiments indicated that GA₄₊₇ plus BA treatments could be applied as early as 2 weeks before the mature bud stage without compromising the positive effects.     

The influence of increasing tree cover on mean radiant temperature across a mixed development suburb in Adelaide,Australia

The implementation of trees in urban environments can mitigate outdoor thermal stress. Growing global urban population and the risk of heatwaves, compounded by development driven urban warmth (the urban heat island), means more people are at risk of heat stress in our cities. Effective planning of urban environments must minimise heat-health risks through a variety of active and passive design measures at an affordable cost. Using the Solar and Longwave Environmental Irradiance Geometry (SOLWEIG) model and working within the bounds of current urban design, this study aimed to quantify changes in mean radiant temperature (T_mrt) from increased tree cover at five different 200 × 200 m urban forms (including compact mid-rise development, residential and open grassy areas) within a suburb of Adelaide, Australia during summer. Following a successful validation of SOLWEIG, street trees were strategically distributed throughout each of the five urban forms and the model run over five warm sunny days (13–17 February 2011). Results showed spatially averaged daytime (7:30–20:00) T_mrt reduced by between 1.7 °C and 5.1 °C at each site, while under peak heating conditions (16 February, 14:00) T_mrt reduced by between 2.0 °C and 7.1 °C. The largest reduction in T_mrt under peak warming conditions was at the residential site, despite having the fewest number of trees added. Directly below clusters of trees, T_mrt could be reduced by between 14.1 °C and 18.7 °C. SOLWEIG also highlighted that more built-up sites showed higher T_mrt under peak warming conditions due to increased radiation loading from 3D urban surfaces, but over the course of the day, open sites were exposed to greater and more uniform T_mrt. This study clearly demonstrates the capacity of street trees to mitigate outdoor thermal stress and provides guidance for urban planners on strategic street tree implementation.     

Embryo induction via anther culture in papaya and sex analysis of the derived plantlets

We investigated the embryo induction of papaya by anther culture, and identified the sex of plantlets derived from embryos using a sex-diagnostic PCR. Anthers, containing approximately 80% uninucleate pollen, were collected from 10 to 14 mm long male flower buds. They were pre-treated on agar (0.8%) or in liquid medium for 1–5 days at 25 or 35 °C, then transferred to agar medium with 0.1 mg l⁻¹ BA and 0.1 mg l⁻¹ NAA. Agar and liquid media used for the pre-treatment contained water only or MS nutrients with or without sucrose (2.0%). On the agar medium, no embryos were induced at any pre-treatment temperature. In the liquid medium at 25 °C, embryos were induced at about 1.0% (rate of anthers forming embryos) in MS medium with sucrose for 3 or 5 days. At 35 °C, embryo induction rate tended to increase up to about 4.0% when anthers were treated in water for 1 day or MS medium with sucrose for 3 or 5 days. The sex of plantlets established through anther culture was analyzed using a sex-diagnostic PCR. All plantlets were determined as female. From these results, we suggest that all plantlets established through anther culture were of microspore origin, and that the anther culture technique is useful for the breeding of female papaya.     

Effect of low temperature on breaking dormancy and flowering of Arisaema sikokianum (Araceae)

Arisaema sikokianum (Araceae) native to Japan is classified as a vulnerable species in the Red Data Book of Japan. Control of dormancy is essential for efficient corm production and forcing culture. Sprouting of both vegetative and reproductive corms was enhanced by exposure to low temperature. Vegetative corms exposed to low temperatures at 5 °C longer sprouted faster when grown at 20 °C. Effective temperatures for breaking dormancy was 5 °C. Reproductive corms treated at 5 °C longer showed shorter days to flower. Successful forcing culture was achieved; corms treated at 5 °C from November for 30 days flowered on 5th February.     

The temperature and photoperiod regulation of flowering and runnering in the strawberries,Fragaria chiloensis,F. virginiana,and F. x ananassa

The temperature and photoperiod interactions of a number of elite genotypes of Fragaria virginiana, F. x ananassa, and F. chiloensis were studied in a series of growth chamber experiments. Several parameters were evaluated including: (1) the critical day-length (CDL) for flowering of short day (SD) genotypes under 8, 9, 10, and 11 h days at 18 °C, (2) the floral and runnering response of single and multiple cropping genotypes under 8 and 16 h days at 18 °C, and (3) the effect of temperature on flower bud formation in day-neutral (DN) genotypes held at 18, 22, 26, and 30 °C under 12 h day-lengths. The same number of flowers were initiated under 15 and 30 day induction periods, regardless of photoperiod. Frederick 9, LH 50-4 and RH 30 (F. virginiana), ‘Aromas’ and ‘Tribute’ (F. x ananassa) and CFRA 0368 of F. chiloensis flowered under both long days (LDs) and SDs; while Eagle-14 (F. virginiana), ‘Fort Laramie’ and ‘Quinalt’ (F. x ananassa) flowered only under long days. While those genotypes that flowered under both LD and SD can be considered day-neutral, they varied in the degree of floral response to the two photoperiods. CFRA 0368 and Frederick 9 produced the same number of flowers under both LDs and SDs, while ‘Aromas’ and ‘Tribute’ had more flowers under LDs and RH 30 had more under SDs. Of the DN genotypes, LH 50-4 and RH 30 were the only ones that produced runners under SDs. Flowering in ‘Fort Laramie’ was least affected of any genotype by high temperature, although its dry weight was negatively impacted. Based on these data, several genotypes show promise as breeding parents: CFRA 0368 and Frederick 9 to equalize flower production under LD and SD conditions, LH 50-4 and RH 30 to produce more freely runnering DNs, and ‘Fort Laramie’ for floral heat tolerance.