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THECOMMERCIAL GREENHOUSEGROWER • MARCH 2017
RESEARCHDIARY •
Research
Diary
Mycorrhizal Inoculum affect yield and
chemical composition of fruit in tomato
Studies in Poland set out to determine the yield and chemical
composition of the fruits of four tomato cultivars ‘Growdena
F1’, ‘Torero F1’, ‘Listell F1’ and ‘Mamirio F1’ grown in coir
fibre inoculatedwithmycorrhizal fungi of the genusGlomus
(HortorumCultus). Themycorrhizal inoculumwas applied
directly to the coir fibre, at 20 g per m2.
The total andmarketable yields of tomato fruitswere influenced
by the cultivar the highest yieldswere obtained fromplants of
‘Torrero F1’ cv. and lowest yields from ‘Mamirio F1’ cv. Tomato
plants that received themycorrhizal inoculum, except cv.
‘Torero F1’, produced higher yields than control plants. The fruit
of cv. ‘Mamirio F1’ had the highest content of drymatter, total
sugars, reducing sugars and L-ascorbic acid, nitrates and the
lowest weight of fruit.
Antagonism against the pathogenic fungus by
non-antagonistic bacteria in hydroponics
The rhizospheremicrobial community contributes to
suppression of root-borne diseases to varying degrees.
Scientists at theNational Agriculture and FoodResearch
Organization in Japan. Testedwhether this phenomenon
can be attributed to the interplay of non-antagonistic bacteria
rather than to a single antagonisticmicrobe. They investigated
the potential roles of bacterial interplay in the suppression of
the fungal phytopathogen Fusarium oxysporum (Journal of
Phytopathology).
Bacterial strains isolatedwere subjected to in vitro and in
planta tests on F. oxysporum. A community of seven bacterial
strains (Kaistia sp. TBD58, Sphingopyxis sp. TBD84, Bosea
sp. TBD101, Ancylobacter sp. TBD132, Cupriavidus sp.
TBD162, Brevibacillus sp. TBD179 andSphingopyxis sp.
TBD181) suppressed F. oxysporum growth. None of the
strains alonewas antagonistic against F. oxysporum, whereas
several pairs of these strains inhibited its growth. Observations
showed the formation of swollen F. oxysporum cells in the
presence of these bacterial pairs. The same bacterial pairs
also suppressed Fusariumwilt disease inArabidopsis thaliana.
The results indicate that a complex bacterial interplay among
non-antagonistic bacteria can significantly contribute to the
development of antagonism against disease organisms
Root-zone heating and development of
Petunia at lower air temperature
Heating accounts for up to 30% of total operating costs for
greenhouse operations in northern latitudes. Growers often
lower air temperatures for production to reduce energy costs
but this can delay development even in cold-tolerant crops,
such as petunia, increasing production time and reducing
profitability. Recent studies on low air temperature bedding
plant production indicate petunia as a strong potential
candidate for using lower air temperatures in combination
with bench-top root-zone heating to avoid or reduce delays in
development. Researchers at PurdueUniversity, investigated
this further to quantify time to flower of seven petunia cultivars
and two recombinant inbred lineswhen themean daily air
temperaturewas lowered by 5 °C and bench-top root-zone
heatingwas used anddetermine if a high-quality petunia crop
can be produced on root-zone heating (HortScience).
Petunia ‘SunSpunBurgundy’, ‘SunSpun Lavender Star’,
‘Sanguna PatioRed’, ‘Potunia Plus Red’, ‘Potunia Plus Purple’,
‘SupertuniaRed’, ‘SupertuniaBordeaux’, and two recombinant
inbred lines, were grown in a greenhousewith amean daily
air temperature of 15 °Cwithout root-zone heating or with a
root-zone heating set point of 21, 24, or 27 °C. Additionally, a
commercial control was established by growing plantswithout
root-zone heating at amean daily air temperature of 20 °C. All
plantswere grown under a 16-hour photoperiod to provide a
daily light integral of ≈12mol•m−2•d−1. Time to flower was
shorter at higher root-zone heating set points. For example,
time to flower of ‘Potunia Plus Red’ was 56, 52, 49, or 47
days for plants grown at mean daily air temperature of 15 °C
without root-zone heating, or with root-zone heating set points
of 21, 24, or 27 °C, respectively.When a root-zone heating
set point of 27 °Cwas employed, time to flower of all cultivars
and inbred lines, except ‘Potunia Plus Red’ and ‘Sanguna Patio
Red’, comparable to plants grown in the commercial control.
Shorter stem length, lower growth index, and smaller shoot dry
mass at floweringwere observed for plants grown under lower
air temperatureswith root-zone heating, resulting in amore
compact and high-quality plant. Producing a compact plant
in a shorter time is beneficial for growers; results suggest that
mean daily air temperature can be lowered to 15 °C for petunia
productionwhen a root-zone heating set point of 27 °C is
employed.
