16
F
Pol yt
u
nn
e
l s
F
www
.a
c
tp
ub
.
c
o.
u
k
The FruITGrOwer • December 2016
u
s
e
d to id
e
ntify and
me
as
ure
t
he
total a
re
a of p
r
od
uc
tion in
polyt
u
nn
e
ls.
w
he
n it
c
o
me
s to
ch
oosing a t
u
nn
e
l fo
r
t
he
p
r
od
uc
tion of
e
di
b
l
e
cr
ops,
much
d
e
p
e
nds on t
he
s
c
al
e
of p
r
od
uc
tion.
A
cc
o
r
ding to L
e
s Lan
e
of XLho
r
ti
cu
lt
ure
,
m
any of t
he
diff
ere
n
ce
s
be
t
wee
n t
he
re
q
u
i
reme
nts fo
r
p
r
od
uc
ing
e
di
b
l
e
and o
r
na
me
ntal
cr
ops a
re
asso
c
iat
e
d
w
it
h
c
osts. “edi
b
l
e
s,
pa
r
ti
cu
la
r
ly soft f
ru
it, a
rew
o
r
king on a vast s
c
al
e
. In
polyt
he
n
e
t
erm
s, fo
r
e
xa
m
pl
ew
it
h
st
r
a
wberr
i
e
s,
we
h
av
e
so
me
cu
sto
mer
s
w
it
h
200
h
a of t
u
nn
e
ls, so t
he
c
osts of
b
ot
h
t
he
polyt
he
n
e
and t
he
st
ruc
t
ure
s
bec
o
me
cruc
ial. T
he
fi
e
ld-
s
c
al
e
p
r
od
uc
t
h
as got to
bemuch
che
ap
er
t
h
an t
h
at
u
s
e
d fo
r
ot
her
p
ur
pos
e
s. Yo
uw
o
u
ldn’t
u
s
e
t
he
sa
me
fil
m
s, s
uch
as
o
ur
g
ree
n and
b
l
ue
fil
m
s, on o
r
na
me
ntal
cr
ops,
bu
t t
he
c
l
e
a
r
and diff
u
s
e
d fil
m
s a
re
si
m
ila
r
a
cr
oss
b
ot
h
e
di
b
l
e
and
o
r
na
me
ntal s
ec
to
r
s,” said L
e
s.
P
r
od
uc
tion
u
sing Spanis
h
t
u
nn
e
ls o
r
, as t
he
A
mer
i
c
ans
c
all
t
hem
, ‘
h
ig
h
’ t
u
nn
e
ls, t
e
nds to
be
c
on
ce
nt
r
at
e
d on fi
e
ld-s
c
al
e
p
r
od
uc
tion, alt
h
o
u
g
h
s
uch
st
ruc
t
ure
s a
re
oft
e
n
u
s
e
d fo
r
cu
t
flo
wer
p
r
od
uc
tion as
we
ll. La
r
g
e
-s
c
al
e
e
di
b
l
e
cr
opping falls
be
t
wee
n t
he
typ
e
of p
erm
an
e
nt st
ruc
t
ure
oft
e
n
u
s
e
d
b
y
la
r
g
e
-s
c
al
e
salad p
r
od
ucer
s, and t
he
t
em
po
r
a
r
y typ
e
s
u
s
e
d
b
y f
ru
it g
r
o
wer
s. “Fo
r
salad g
r
o
wer
s g
r
o
w
ing la
r
g
e
vol
ume
s of
salad l
e
av
e
s
u
nd
er
polyt
he
n
e
, yo
u
a
re
u
sing a p
erm
an
e
nt
st
ruc
t
ure
, and t
here
fo
re
p
u
tting a polyt
he
n
e
on
wh
i
ch
is going
to last fo
r
10 o
r
12 y
e
a
r
s. T
h
is
me
ans t
h
at t
he
p
r
i
ce
is not so
cr
iti
c
al,”
e
xplains L
e
s. “b
ec
a
u
s
e
f
ru
it
cr
ops s
uch
as
st
r
a
wberr
i
e
s,
r
asp
berr
i
e
s,
b
l
ueberr
i
e
s and
cherr
i
e
s
re
q
u
i
re
pl
e
nty of ai
r
, t
he
polyt
he
n
e
is p
u
s
he
d
u
p and do
w
n
t
hr
o
u
g
h
o
u
t t
he
s
e
ason to p
r
ovid
e
t
he
l
e
v
e
l of v
e
ntilation
re
q
u
i
re
d to
c
ont
r
ol t
he
t
em
p
er
at
ure
. T
he
la
r
g
e
a
re
as involv
e
d
n
ee
d a lo
w
-
c
ost sol
u
tion.” T
he
rem
oval of t
he
polyt
he
n
e
fo
r
pa
r
t of t
he
y
e
a
r
is also
e
ss
e
ntial if t
he
st
ruc
t
ure
is to
be
c
lassifi
e
d as a t
em
po
r
a
r
y st
ruc
t
ure
u
nd
er
planning
ru
l
e
s.
ho
we
v
er
,
re
g
u
la
r
ly p
u
s
h
ing t
he
polyt
he
n
e
u
p and do
w
n
me
ans t
h
at it
c
an
be
p
h
ysi
c
ally da
m
ag
e
d. cons
e
q
ue
ntly,
m
an
u
fa
c
t
urer
s lik
e
XLho
r
ti
cu
lt
ure
p
r
od
uce
fil
m
s fo
r
t
he
s
ec
to
r w
it
h
anti
c
ipat
e
d lif
e
spans of a
r
o
u
nd fiv
e
s
e
asons.
“T
he
fil
m
s
h
av
e
to allo
w
uV lig
h
t to pass t
hr
o
u
g
h
as t
h
at
in
cre
as
e
s t
he
b
r
ix l
e
v
e
ls in t
he
f
ru
it,” adds L
e
s. “ho
we
v
er
, it is
a v
er
y
c
o
m
pli
c
at
e
d, t
ech
ni
c
al fil
m
and
wem
ak
e
six diff
ere
nt
fil
m
s fo
r
t
h
is
m
a
r
k
e
t.” As
we
ll as t
he
p
h
ysi
c
al st
r
ains i
m
pos
e
d
b
y
re
g
u
la
r m
ov
eme
nt, t
he
soft f
ru
it s
ec
to
r
pla
ce
s additional
st
r
ains on fil
m
s. In t
he
last f
ew
y
e
a
r
s t
he
ind
u
st
r
y
h
as lost a
n
umber
of
cr
op p
r
ot
ec
tion
chem
i
c
als,
wh
i
ch
h
as s
ee
n t
he
a
m
o
u
nt of s
u
lp
hur
u
s
e
d
b
y g
r
o
wer
s in
cre
as
e
, pa
r
ti
cu
la
r
ly in
e
v
erbe
a
rer
st
r
a
wberr
y va
r
i
e
ti
e
s. “S
u
lp
hur
and
ch
lo
r
in
e
a
re
t
he
t
w
o
b
igg
e
st
e
n
em
i
e
s of t
he
uV sta
b
ilis
er
s
u
s
e
d in fil
m
s,”
points o
u
t L
e
s. “A no
rm
al fil
mw
ill
h
av
e
a
re
sistan
ce
of
500pp
m
of s
u
lp
hur
,
bu
t
we
no
wm
ak
e
all of o
ur
s
re
sistant to
a l
e
v
e
l of 700pp
m
,
wh
i
ch
t
e
sts
h
av
e
s
h
o
w
n is ad
e
q
u
at
e
fo
r
no
rm
al f
u
ngi
c
id
e
and p
e
sti
c
id
e
u
sag
e
ov
er
fo
ur
to fiv
e
y
e
a
r
s.
w
e
also
m
ak
e
anot
her
fil
m
c
all
e
d S
u
lp
hur
Saf
ewh
i
chme
ans
t
h
at g
r
o
wer
s
c
an
u
s
e
as
much
s
u
lp
hur
as t
he
y n
ee
d. w
e
m
ak
e
a t
herm
i
c
fil
m
and anot
her
, D
ur
aLit
e
c
ool, t
h
at
h
as
m
i
cr
o-fin
e
al
um
ini
um
pa
r
ti
c
l
e
s in it. T
h
is
h
as p
r
ov
e
d pop
u
la
r
w
it
h
so
me
la
r
g
e
b
l
ueberr
y g
r
o
wer
s in S
c
otland as it
e
na
b
l
e
s
t
hem
to stagg
er
t
he
i
r
h
a
r
v
e
st dat
e
s and g
e
t
be
tt
er
p
r
i
ce
s.”
It is not j
u
st f
ru
it s
u
ga
r
s t
h
at a
re
infl
ue
n
ce
d
b
y t
he
uV
p
r
op
er
ti
e
s of t
he
fil
m
. r
e
s
e
a
rch
at t
he
univ
er
sity of r
e
ading
h
as s
h
o
w
n an
e
ff
ec
t on t
he
yi
e
ld and
chem
i
c
al
c
o
m
position
of l
e
tt
uce
. In t
r
ials, t
he
g
r
o
w
t
h
and p
r
od
uc
tion of
ant
h
o
c
yanin, flavonoid and p
he
noli
c
c
o
m
po
u
nds
were
e
val
u
at
e
d in t
he
Lollo rosso l
e
tt
uce
va
r
i
e
ty ‘r
e
vol
u
tion’
g
r
o
w
n
c
ontin
u
o
u
sly
u
nd
er
fil
m
s va
r
ying in t
he
i
r
a
b
ility to
t
r
ans
m
it uV
r
adiation. Plants
u
nd
er
a
c
o
m
pl
e
t
e
uV
b
lo
c
king
fil
m
p
r
od
uce
d
u
p to 2.2 ti
me
s
m
o
re
total a
b
ov
e
-g
r
o
u
nd d
r
y
we
ig
h
t t
h
an plants
u
nd
er
t
he
uV-t
r
anspa
re
nt fil
m
,
bu
t t
he
ant
h
o
c
yanin
c
ont
e
nt in plants
u
nd
er
t
he
uV-
b
lo
c
king fil
mw
as
app
r
oxi
m
at
e
ly
e
ig
h
t ti
me
s lo
wer
t
h
an in plants
u
nd
er
a uV-
t
r
anspa
re
nt fil
m
.
To f
ur
t
her
c
o
m
pli
c
at
em
att
er
s fo
r
g
r
o
wer
s,
wh
il
e
uV-
t
r
ans
m
itting fil
m
s in
cre
as
e
t
he
n
u
t
r
i
e
nt
c
ont
e
nt of f
ru
its, in
t
r
ials, uV-
b
lo
c
king fil
m
s
h
av
e
he
lp
e
d to
c
ont
r
ol p
e
sts and
dis
e
as
e
s s
uch
as ap
h
ids, t
hr
ips andbot
r
ytis. A
cc
o
r
ding to
t
he
univ
er
sity of r
e
ading, t
he
d
e
v
e
lop
me
nt and
c
o
mmerc
ialisation of nov
e
l fil
m
s
h
as
he
lp
e
d to
e
xpand t
he
b
r
itis
h
st
r
a
wberr
y g
r
o
w
ing s
e
ason f
r
o
m
e
ig
h
t
wee
ks to on
e
t
h
at no
w
e
xt
e
nds f
r
o
m
sp
r
ing to a
u
t
um
n. Alt
h
o
u
g
h
t
here
a
re
m
any fa
c
to
r
s
re
sponsi
b
l
e
fo
r
in
cre
as
e
d st
r
a
wberr
y yi
e
lds in
t
he
uK, r
e
adinguniv
er
sity’s
re
s
e
a
rch
into sp
ec
t
r
al fil
m
s
h
as
bee
n on
e
of t
he
c
ont
r
i
bu
ting fa
c
to
r
s. T
he
ch
all
e
ng
e
fo
r
b
ot
h
fil
mm
an
u
fa
c
t
urer
s and g
r
o
wer
s
c
ontin
ue
s to
be
h
o
w
be
st to
u
tilis
e
t
he
lat
e
st
re
s
e
a
rch
in p
r
od
uc
ts t
h
at a
re
not too
c
ostly
fo
r
u
s
e
on t
he
s
c
al
e
re
q
u
i
re
d fo
r m
any
e
di
b
l
e
cr
ops.
◆
