16 / 10 / 2017

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نقش عناصر غذای در کیفیت تاکستانها Influencing Table Grape Quality

نقش عناصر غذای در کیفیت تاکستانها Influencing Table Grape Quality

Influencing Table Grape Quality

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Table Grape

Table grape quality standards vary between countries. Many have been established as a result of local preference, taste and tradition. Maintaining high sugars and a juicy berry by manipulating the time of maturity is important for marketability. ترجمه و تحلیل از سید محمودجعفری انچه ما میدانیم از تجربیات زحمات گذشته است لیکن با این حال هر چه جستجو کنی باز هم مطالب بسیار است و ما نمی دانیم
که بایستی کنجکاو باشیم تا در یابیم…
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External Quality

Table grape berries must be of good external quality and attractive appearance to meet the market specifications.

The major external quality parameters of grape berries include color, even size, skin firmness, pulp stability, and strength of attachment to the bunch stalk.

Internal Quality

The internal quality of table grape is of big importance. The desired level of sweetness is a matter of personal taste and preference. Sweetness of berry is expressed as the Sugar/Acid ratio. A measure of the sugar in the grape or Total Soluble Solids (TSS) content is usually obtained from assessing the oBrix of the fruit.

Application of the right amount of nutrients is the major crop management practice required to produce high quality table grape.

Crop Nutrition and Table Grape Quality

Macronutrients

Supply of sufficient amount of macronutrients (N, P, and K) can improve table grape quality. Nitrogen is needed to produce better quality berries, because it enhances growth and development of crop. Application of N fertilizer resulted in higher sugar content of berries. Too much nitrogen, however, can lead to soft table grapes at harvest.

Potassium is a key component of nucleic acids and lipids. Thus it enhances growth and development that can increase quality of table grape. K plays the central role during transportation of photosynthetic products to support growth and development processes. Potassium increases berry size and evenness and it is also applied to improve skin color. Application of K fertilizer results in increase of sugar/acid ratio of grape berries.

Deficiency of secondary nutrients (calcium and magnesium) can negatively affect quality of table grape. Calcium is a key component of cell walls maintaining the membrane structure and also directly influences regulation of enzyme systems, phyto-hormone activities, and nutrient uptake. Post-harvest berry quality is specifically influenced by Ca nutrition. It is very important to maintain sufficient level of Ca in berry skin via Ca applications to the vine throughout the season and/or Ca sprays targeted during fruit development. Calcium sprays directly on the fruit, especially late in the season during fruit maturity, are important to improve strength of skin, and storage and handling characteristics.

Micronutrients

Application of sufficient amount of micro nutrients is resulted in better growth and development of table grape, because micro nutrients deficiency can limit growth and development of berries. Boron enhances germination of pollen and fruit set. Application of boron fertilizer resulted in increase of sugar content.

Iron is essentially required for early leaf production and photosynthesis to ensure better berry development and quality. Supply of sufficient amount of Fe fertilizer resulted in increase of sugar content.

Zinc is involved in process of chloroplast development, thus it is essential for improvement of grape quality. Zinc fertilizer application resulted in increase of sugar content and reduction of post-harvest weight loss .

Find Yara Advice on Every Table Grape Quality Issue

Improving table grape skin strength/firmness

Improving Table Grape Skin Strength/Firmness

One of the most important quality factors for table grape, which determines the eating quality, is skin firmness.

Influencing TSS/sugar content

Influencing Total Soluble Solids/Sugar Content and Acidity in Table Grape

Sweetness of the grape berry is expressed as the sugar/acid ratio.

Improving Juice Content in Table Grape

Improving Juice Content in Table Grape

One important quality factor influencing table grape quality is table grape juice content.

Influencing table grape color

Influencing Table Grape Colour

Most consumers seek a large, evenly sized grape bunch of consistent appearance.

Improving storage quality of table grapes

 و اطلاعات بیشتر در ارتباط با انواع کودها ونحوه مصرف ان ترجمه در ایندهImproving Storage Quality of Table Grapes

It is important to prevent deterioration of fruit quality after harvesting and assure long shelf life of the crop

شاهرودی

Foliar Fertilization of Grapevines
By Peter Christensen, Extension Viticulturist
The U
niversity of California Kearney Agricultural Center
VineLines Editor’s Note:
Because the question applying nutrients by foliar sprays comes up
often, I’m including comments by one of the world’s leading experts in the field. Some
comments relate to California vineyards, but the observations are valid for Midwest vineyards.
Applying nutrients to the foliage is widely practiced in fruit crop production. In many instances it
may not be providing any benefit except to the manufacturer and dealer. So, when is it effective
and economical? The literature is full of reports on folia
r fertilization studies. This
article brings
some of the information to light in hopes that it will lessen the confusion,
mysteries, and expense
of this practice.
Micronutrients
Nutrient foliar sprays are most commonly
practiced to correct micronutrient problems (
9). There
are several good reasons for this.
Micronutrients such as zinc, boron, manganese, and iron are
required in relatively small
quantities by plants. Thus, foliar sprays can prevent or correct a
problem with relatively
small amounts absorbed by the foliage. The
heavy metals such as zinc,
manganese, and iron are also readily fixed by most soils. Thus, they are not free to move or
remain available in the soil as a fertilizer (
3).
Zinc.
Foliar spray of zinc is the most common
because it is the most widely deficient
micronutrient. Treatment can also be quite
effective if the correct material and methods of
application are used (9). Neutral zinc (52% Zn)
and zinc oxide (75% Zn) are the most
economical and effective on a recommended
label basis (6
,7,10). There is no advantage in using
chelated zinc products in sprays. They
were originally intended for soil application, are
more
expensive, and less effective than neutral
zinc and zinc oxide on a label recommended basis.
Uptake is greatest with dilut
e application as compared to concentrate (
7).
The optimum
timing to
influence fruit set is three weeks before bloom up to bloom (
8).
Boron.
Boron can also be applied as a foliar
spray but it is most commonly applied to the
soil via
a berm herbicide spray (
11). Two to three pounds of Soluborr (20% B) per acre per
foliar
application is recommended, not to exceed a total of five pounds per year (
3).
Manganese.
Manganese deficiency is rare to
San
Joaquin Valley vineyards and is occasionally
seen in Coachella Valley and North Coast. It is readily corrected with manganese
sulfate at 2 to 3
pounds per 100 gallons (
3,9,15).
There are no advantages in using chelated
manganese in a foliar
spray (
15).
Iron.
Iron deficiency is by far the most difficult
to correct. T
his is because it is fixed in the tissue
with little or no translocation to growing
regions. Often, the leaves themselves do not
recover
uniformly and are freckled with green spots indicating localized immobilization (3).
Usually, it is
necessary to apply repeated sprays at top label rates to get any degree of acceptable correction
(9). The literature contains
conflicting reports as to whether the iron chelates or inorganic salts
are more effective (
26). However, iron chelates are the most
widely used by gr
owers.
Combination Micronutrients.
Using products
that contain various micronutrients is a common
practice, especially as a “maintenance”
philosophy. However, most commonly only one
micronutrient is marginal or deficient in any
particular vineyard and there isn’t enough of any
one of the elements in the product to correct a
deficiency anyway. It is better to first determine
what elements are marginal or deficient through
petiole analy
sis. This is also a good way to
confirm symptoms as some of the
micronutrient symptoms are easily confused. Once a potential
deficiency has been diagnosed, a single element
compound spray can be
used to prevent or
correct it (3,9,10,26).
There is one problem to be aware of in using tissue an
alysis for micronutrients.
Iron deficiencies
are caused by its immobilization in
plant tissue and not total uptake (3). Thus, iron deficient
tissues will not be necessarily low in
iron. Often as not, iron levels will be as high in deficiency
symptom tissues as in normal tissue (
9). It is best to ask the laboratory to skip iron
analysis to
lower the cost of analysis and to
avoid confusion or misinterpretation.
Macronutrients
Foliar fertilization with macronutrients such as
nitrogen, phos
phorus, potassium, calcium, and
magnesium is a more muddied issue than with micronutrients
. It is common to see them used
even though they are being adequately supplied by the soil and root uptake. It is a way to “cover
all the bases” and it’s usually just the cost of
material to
consider as the spray is being
directed to
something else anyway.
There are several weaknesses in the idea of
foliar feeding
macronutrients (3,26). First, the
nutrient is probably being supplied adequately via the soil.
Second, there wouldn’t be enough absorption of the macronutrient to correct a
deficiency for
very long, if at all. And third, all
the evidence in the literature shows it to be an
ineffective or
impractical method to
significantly supply macronutrients to
grapevines.
Nitrogen.
Nitrogen applied to the foliage as
urea is a commercial practice in apples and
citrus
(3,14,26). These crops apparently absorb nitrogen better than most other. It is mostly used
to
supplement soil treatments as it sometimes takes six or more applications in one season to
provide all of the nitrogen needs. Urea has also
been tried on peaches and grapes with no
measured benefit or increase in leaf nitrogen
levels (
3,10,17,20,26).
Phosphorus.
Phosphorus foliar applications
have resulted in few reports of responses on any
crop (3,26). Repeated
sprays of phosphorus
(three per season) over two years in five
replicated
vineyard trials gave no response and
did not increase phosphorus levels in the
growing shoot tips
(13). Phosphorus deficiency has not been documented in San Joaquin Valley vineyards (
9).
Potassium.
Potassium is required by most fruit
crops in too large a quantity to be practically
supplied through the leaves. Foliar potassium
nitrate has been recommended in prune orchards
as
an interim corrective measure until soil applications take effect (
22,25). It is not
recommended in
most other fruit crops because
of a lack of response (
22,25,26
). Research in
grapes has shown no
effect on deficiencies or
increases in foliar tissue potassium levels (10,19,23).
Potassium nitrate has not shown benefit in
supplying nitrogen to fruit crops (25,26).
Weinbaum
(26) determined that 2
-year
-old
prune trees would require 140 applications of
1.2% potassium
nitrate per year to meet their requirement.
Calcium.
Foliar applications of calcium are
recommended
fo
r fruit disorders of some crops
(3,26). A notable example is bitter pit of apple. Calcium foliar spray applications were
evaluated
for reducing “waterberry” our most important fruit disorder. No reductions of
“waterberry” or
any other fruit effects were found (4,5). Actually
, calcium nitrate increased
“waterberry.” This
was later found to be due to the increased nitrogen from the nitrate.
“Waterberry” affected tissues
in clusters have elevated levels of nitrogen compounds and symptoms can be induced with
nitrogen
applications. Thus, foliar nitrogen applications
may actually be counter
-productive in
some
cases.
Magnesium.
Magnesium sulfate sprays are recommended on some crops to correct
magnesium
deficiency (3,4,5,18,26). It may be
tried on grapes as an in
terim corrective measure along with
soil applications. It would be a
suitable substitute for soil application under a deficiency situation
(9).
Macronutrient Combinations.
This is the most
controversial use of foliar nutrients. There is a
constant barrag
e of claims that such products
result in improved vine growth, production, and
fruit quality. However, it doesn’t seem logical
that vines which are absorbing adequate
amounts
of macronutrients from the soil would respond to additional foliar applications. Also,ای نام تو بهترین سر اغاز سید محمود گوید در فارس در زمان رسیدن انگو حتما از منطقه دشمن زیاری برای ابغوره
و برای رقم های انگور چند رقم  سمرقندی و ریش بابا و شاهرودی در بیضا دیدن نمایید در اطراف گویم و کلستان سیاه و رطبی و عسکری در نیریز نهالستان بهرام زارعی از انگور بی هسته فلیم با رنگ قرمز .تصویر انگور مورد نظر
they would
be absorbed in such small quantities
that they would be largely ineffective.
This logic is supported by trials in other fruit
crops and in grapes (1,2,3,13,18,21,26). For
example, multiple sprays of NPK products over
four years have produced no response (21).
However, claims of the “magical” effects of
NPK foliar sprays will no doubt continue. They are
usually based on non-
replicated trials and
endorsements. The best way to make a judgment
is to
put out trials of your own. The trial should not merely compare one 10 acre block with another,
for example. This can be misleading
due to vine differences. It is best to treat only a few rows
and leave a check of a few rows. This should be replicated or repeated three or four
times across
the field
. This way, you can avoid natural vine differences across the field in your
comparisons.
Tank mixing is another consideration. Several
pesticides have shown increased phytotoxicity
when foliar nutrients are added. “Witches brew”
tank mixes sometimes appear to contribute to
berry scarring. It is possible that adding an unnecessary foli
ar nutrient can tip the balance
towards scarring. Therefore, make sure the
nutrient is n
eeded. Otherwise, it may not be worth the
risk. If there is any question about
combinat
ions or compatibility, first try it on a
limited number
of vines.
Summary
In summary, foliar nutrient sprays can be quite
effective in correcting deficiencies of
micronutrients. It is best to first determine
which element is marginal or deficient and to
a pply
only that element in inorganic form. The
only exception is iron which is only marginally
effective as a foliar spray and usually applied as
a chelate. Macronutrients are generally not
effective or practical as foliar fertilizers.
Deficiencies or maintenance can be corrected or
supplied through soil applications. Questions
can be answered by establishing replicated trials
in
individual vineyards. And finally, be cautious
about tank mixes.

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