. The cultivated strawberry, Fragaria × ananassa Duch., is one of the most economically important fruit crops in the world. It first arose from accidental hybridization between two American octoploid species, F . virginiana and F . chiloensis
Masanori Honjo, Sono Kataoka, Susumu Yui, Masami Morishita, Miyuki Kunihisa, Takayoshi Yano, Megumi Hamano and Hiromichi Yamazaki
James F. Hancock, Chad E. Finn, James J. Luby, Adam Dale, Pete W. Callow and Sedat Serçe
The founding genetic base of the commercial strawberry, Fragaria × ananassa Duchesne in Lamarck, is limited. It originated ≈250 years ago when a few clones of South American F. chiloensis chiloensis (L.) Miller subsp. chiloensis forma
Aaron J. Brown
Polyethylene glycol (PEG) was evaluated for its influence on hardening of in vitro-propagated `Fern' strawberries (Fragaria ×ananassa) when applied just before transplanting. Strawberries were micropropagated via shoot tips and grown in vitro until roots were well developed. Plantlets were then transferred onto filter paper bridges in liquid medium with 15% (w/v) of PEG-8000. After treatment in the medium for various periods, the plants were compared to the control (no PEG) for water loss from detached leaves, stomatal aperture, and survival rates after transplanting. Leaf epicuticular wax was also quantified. Overall, the in vitro PEG treatment was not successful in significantly increasing hardiness and survivability of the strawberry plants after transplanting from in vitro conditions to a soil medium. Osmotic stress was created, but apparently not for the time needed to increase survival. Further tests are needed to pinpoint the proper exposure time required to increase hardiness and survivability after transplanting plantlets. To increase survival, the time exposed to PEG should be 15, 18, or possibly 21 days.
Sorkel Kadir, Gaganpreet Sidhu and Kassim Al-Khatib
Thermotolerance of photosynthesis and productivity in `Chandler' and `Sweet Charlie' strawberry plants (Fragaria ×ananassa Duch.) exposed to three temperature regimes was studied. Net CO2 assimilation rate (A), variable chlorophyll fluorescence (Fv), efficiency of photosystem II (Fv/Fm), relative chlorophyll content, plant growth, and fruit yield and quality were measured. High temperature (40 °C day/35 °C night) was more detrimental to photosynthesis and productivity than the moderate or low temperature (30/25 or 20/15 °C). Net CO2 assimilation rate in both cultivars was markedly reduced by 40/35 °C, although there was slight decline in `Sweet Charlie' at 30/25 °C. `Chandler' maintained significantly higher A rates than `Sweet Charlie' for at least three weeks of heat stress, indicating that `Chandler' might tolerate longer exposure to high temperature. In parallel to the decrease in A rate, intercellular CO2 concentration (Ci) and instantaneous water use efficiency (WUE) were significantly decreased at high temperature. `Chandler' leaves were cooler and transpired more than `Sweet Charlie' leaves, suggesting that each cultivar adopted different heat resistance mechanisms at 40/35 °C. There were changes in Fv and Fv/Fm with increasing temperature, indicating irreversible damage to photosystem II at 40/35 °C might have occurred. The trend of reduction in stomatal conductance (g S) in both cultivars at high temperature did not coincide with the reduction in A rates. Decline in A rates at high temperature was more related to changes in Fv/Fm than to g S activity. The optimal temperature for vegetative growth was 30/25 °C. Reduction in A rate at high temperature resulted in reduction in total leaf area (LA), shoot, root, and leaf biomasses. Strawberry roots were more responsive than shoot growth to temperatures above 20/15 °C. Fruit yield for `Chandler' was higher at 20/15 °C than at 30/25 °C, suggesting that `Chandler' might have a higher source-to-sink relationship at 20/15 °C than at 30/25 °C. Fruit skin color was temperature dependent only for `Chandler'. A quadratic relationship between flower development and duration of exposure to 30/25 °C for both cultivars was observed; more than two weeks of 30/25 °C can be detrimental to flower development. Regardless of the cultivar and duration of exposure, 40/35 °C was the temperature regime most detrimental to fruit set.
Toshiki Asao, Hiroaki Kitazawa, Takuya Ban, M. Habibur Rahman Pramanik and Kenzi Tokumasa
water and the required amount of benzoic acid was added to reach 400 μ m . Three liters of the test solution was poured into each plastic container (17 cm × 29 cm × 9.5 cm) and then ED treatment was applied as described previously. Strawberry ( Fragaria
Huseyin Karlidag, Ertan Yildirim, Metin Turan, Mucahit Pehluvan and Figen Donmez
, and leaf water content, ionic composition in salt stressed strawberry (Fragaria × ananassa) Sci. Hort. 130 133 140 Karlidag, H. Yildirim, E. Turan, M. 2009 Salicylic acid ameliorate the adverse effect of salt stress on strawberry Sci. Agr. 66 180 187
Lixiang Miao, Yuchao Zhang, Xiaofang Yang, Jinping Xiao, Huiqin Zhang, Ming Jiang, Zuofa Zhang, Yuezhi Wang and Guihua Jiang
-Aldrich (Shanghai, China). All other chemicals and solvents were of analytical reagent grade and were purchased from Sangon Biotech Co., Ltd (Shanghai, China). Plant materials and experimental treatments. Strawberry ( Fragaria × ananassa Duch. cv. Yueli) plantlets
Yuya Mochizuki, Saori Sekiguchi, Naomi Horiuchi, Thanda Aung and Isao Ogiwara
The main cultivation method of strawberry ( Fragaria × ananassa Duch.) in Japan is forcing culture using June-bearing cultivars with flower initiation that is transplanted at the end of September and kept warm from mid October to develop flowers
J.F. Hancock, P.A. Callow and Douglas V. Shaw
Eight strawberry cultivars or advanced selections from the Univ. of California, Davis, breeding program were screened for polymorphisms using the polymerase chain reaction (PCR) and 43 random 10-base DNA primers. Over 60% of the primers screened resulted in replicable polymorphic banding patterns (amplification profiles), and a subset of ten primers that exhibited high levels of amplification profile polymorphism was used to identify each of the eight genotypes uniquely. There was also a significant product-moment correlation (r = 0.64, P < 0.01) between number of shared amplification profile phenotypes and pairwise coefficient of coancestry. This technology shows high promise as a means of verifying the identity of cultivars and developing a genetic map of the octoploid cultivated strawberry.
Brandon Jewell and Chieri Kubota
Feasible protocols for organic hydroponic production of strawberry are necessary and this study compares the yield and fruit quality of organic and conventional inorganic hydroponic production. Some issues identified with organic hydroponic strawberry production are: 1) dominant ammonium nitrogen form; 2) solution alkalinity; and 3) dissolved oxygen level of nutrient solution. Eighty bare-rooted `Diamante' plantlets were planted in coconut fiber pots with a mixture of coconut coir (30%) and perlite (70%) and grown in a modified nutrient film technique system inside a polycarbonate greenhouse. The organic nutrient solution contains mostly ammonium nitrogen and little nitrate nitrogen. To enhance colonization and activities of nitrifying bacteria, coconut fiber mats were placed in the organic nutrient solution reservoir. A similar system was also introduced for stock solution pre-conditioning where nitrification and pH stabilization were achieved before application to the strawberry plantlets. The organic nutrient solution prior to pre-conditioning had only 1.53 mg·L-1 nitrate nitrogen, although the nitrate nitrogen level increased to 63.2 mg·L-1 after pre-conditioning. The organic nutrient solution pH was 4.5 initially, 8.5 after 24 hours of pre-conditioning, and finally, shifted to and stabilized at 5.7–5.9 after 3 days. Dissolved oxygen level is critical for both nitrifying bacteria activities and plantlet root growth; therefore, oxygen enrichment was achieved by constantly aerating the nutrient solution in the reservoir, which raised the oxygen level from 2.5 to 7.4 mg·L-1. Comparisons of yield and quality of strawberry fruits between organic and inorganic nutrient solutions will be presented and further improvements of hydroponic systems will be discussed.