Section ECONOMICS AND TOURISM

PRELIMINARY RESULTS ON THE INFLUENCE OF THE

F414 BIOLOGICAL PRODUCT ON SOME
PHYSIOLOGICAL INDEXES FOR PEACHES GROWN
UNDER THERMO-HYDRIC STRESS
Paraschiv Alina-Nicoleta1
Dima Milica1
Diaconu Aurelia1
Enache Viorel1
2
1
Research- Development Station for Plant Culture on Sands, Dabuleni,
Romania
2
Research-Development Institute for Plant Protection, Bucharest, Romania

ABSTRACT
On the peach species, Springold variety, research was conducted on the
influence of the F414 biological product on some physiological indexes and
processes carried out on the foliar level, the area of culture being characterized by
an accentuated thermo-hydric stress during the summer. Photosynthetic gas
exchange, foliar transpiration and stomatal conductance were determined with the
portable LC PRO + apparatus, and the leaf water forms were determined
gravimetrically, the results obtained being correlated with the meteorological data
from the vegetation period. Applying the F414 to the Springold variety resulted in
the formation of a pellicle on the surface of the leaves, which, together with the
action of the thermo-hydric stress specific to the area, caused stomate closure,
reduction of CO2 supply, photosynthesis values being considerably lower compared
to the control variant. As for foliar transpiration, the F414 product had a positive
effect, the pellicle formed on the surface of the leaves, reducing the amount of water
lost to the foliage. The application of this product has positively influenced drought
resistance of the Springold variety, the percentages of the bound water being higher
(5.1%) compared to the control variant (3.96%).
Keywords: peach, thermo-hydric stress, physiological indexes

INTRODUCTION
The current climatic changes, which, according to experts, will be more and
more pronounced in the coming decades, obviously affect the biology of
horticultural species, especially perennial wood species, such as, for example, fruit
trees. The risk of desertification is a real phenomenon in Romania and is closely
related to the evolution of the climate [8]. The values of the Thornthwaite aridity
index define an arid area, increasing from north to south and south-west of Oltenia,
from 45% to 50%. The highest values expressing pronounced aridity (about 65%)
also cover the area of sandy soils in southern Oltenia [4]. This area therefore has a
natural background favoring a significant drought impact on plants. The plants bear
a temperature rise of 5-10 oC above the optimal temperature, and temperatures
higher than 12-15 oC show the effects of thermal stress [7]. During the vegetation

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period plants are exposed not only to the effects of high temperatures but also to
longer or shorter drought periods. Water is a particularly important abiotic factor
that influences plant metabolism. Water stress is widespread and is the most
important factor limiting production in most crop plants [1]. The response of fruit
trees to water stress is lower than that of annual plants, and varies with the species,
organ and production phenophase [6]. The action of the thermo-hydric stress, as
well as the action of different chemical and biological substances used in
phytosanitary treatments in fruit trees can be appreciated by the level with which
the values of the main physiological and biochemical indicators of the plants
exposed to these factors change. Bioproducts are biological means made on the
basis of natural compounds (plant extracts) with complex action on crop plants,
bioproducts that have been shown to be stimulants for vegetative growth [9], [10].
Taking into account these considerations, the present research has proposed to know
the mode of action of the F414 biological product on peach, the Springold variety,
regarding the influence of this product on some physiological indexes and processes
developed at the foliar level, the area of culture (the sandy soils in southern Oltenia)
being characterized by an accentuated thermo-hydric stress during the summer.

MATERIALS AND METHODS

The studies were conducted during the peach vegetation period (year 2017) at
Research Development Station for Plant Culture on Sands, Dabuleni, Romania,
within the plant physiology laboratory. Springold peach variety was used as study
material in two experimental variants. In the first variant (control) phytosanitary
treatments were applied according to the peach culture technology on sandy soils,
and in the second experimental variant was additionally added treatment with the
F414 biological product. Photosynthetic gas exchange, foliar sweat and stomatal
conductance were determined directly in the experimental field with the LC PRO +
portable device, both on the sunny side of the trees and on the shaded side. The
water forms in the leaves (total water, free, bound) were determined gravimetrically
in the laboratory. The results obtained were correlated with the meteorological data
recorded at the weather station of Dabuleni RDSPCS, during the period April-
October 2017. To determine the intensity of the thermo-hydric stress on the peach
trees, the experimental determinations were made in two critical moments for the
area of sandy soils in southern Oltenia, the first decade of August and September.

RESULTS AND DISCUSSIONS

Experimental determinations made on peach (Springold variety) have
highlighted a diurnal variation in photosynthesis and foliar transpiration processes,
these processes being influenced by the temperature and amount of active radiation
in photosynthesis, the relative air humidity at the time of the determinations, the
amount of rainfall, of treatments applied in vegetation. From the climatic point of
view, the April-October 2017 period is presented in table 1.

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Table 1. Climate conditions between April and October 2017 recorded at the
RDSPCS Dabuleni weather station.
Month IV V VI VII VIII IX X

Medium temperature (oC) 12 17.8 24 24.8 24.8 20.2 13.4

Maximum temperature (oC) 29.8 29 41. 40.8 40.4 36.9 29.4

2
Minimum temperature (oC) 0.4 4.7 12. 13.3 11 6.7 2.7
9
Precipitations (mm) 62.8 78.6 17. 120.8 28.8 18.2 120.4
4
Atmospheric relative humidity 72 77 67 65 63 66 80
(%)
Sum of temperature degrees 360 551.8 720 768.8 768.8 606 415.4
(oC)
Multiannual medium 11.8 16.8 21. 23.1 22.4 17.8 11.4
temperature (1956-2016) 6

Sum of monthly multiannual 47.5 62.12 69. 53.15 37.28 41.81 41.81
precipitations (1956-2016) 2 3

From the data presented, it can be observed that during the analyzed period, the
air temperature is constantly increasing, the monthly average values exceeding the
multiannual average of the temperature. Very warm were the summer months, June,
July and August, with average temperatures between 24 24.8 oC and maximum
air temperature between 40.4 41.2 oC. Due to the atmospheric drought, these high
temperatures led to thermo-hydric stress conditions, which influenced the fruit trees
metabolism, the drought period extending until September. Although the sum of the
annual rainfall was higher than the multiannual sum, they were unevenly
distributed, from very small amounts of about 10 mm to 100 mm in just 2-3 days.
An example of this is June, when 98.8 mm precipitations were recorded in the first
three days of the month, followed by very long periods (28 days) with very high
temperatures and no precipitation. Globally, one of the challenges faced by fruit
production is the fact that the regional climate is increasingly unpredictable from
year to year. Therefore understanding the effects of drought, extreme temperatures,
light, etc. on metabolic processes in plants is very important. In correlation with the
studied factors, the climatic conditions of 2017 directly influenced the development
of physiological processes at the Springold peach variety cultivated on sandy soils.
In the same area of culture, it was demonstrated that as the average temperature of
this area increased, the late Jerseyland and Redhaven peach-trees began to mature
their fruit about 12 days earlier, and the tendency to reduce the vegetation period is
significant [2]. From a physiological point of view, the application of the F414
biological product was aimed at protecting the leaf surface from intense solar
radiation by means of the hydro-active pellicle, the pellicle deposited on the leaves
having a high reflectance when is dry and increased absorbance when is wet.

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However, in the climatic conditions characteristic of the sandy soils in southern

Oltenia, the application of the F414 product led to the formation of the pellicle on
the surface of the leaves which, together with the action of the thermo-hydric stress
specific to the area, caused stomata closure, reduction of the supply of CO 2, and
obtaining leaves with a reduced assimilation surface with repercussions on the
photosynthetic yield (tables 2 and 3).
Table 2. Diurnal variation of physiological processes at Sprindold variety
cultivated under thermo-hydric stress conditions (August 2, 2017).
Prunus persica, Springold variety
Hour Experimental Photosyn- Air Photosyn- Foliar Stomatal
variant thetic temperat thesisµm transpira- conduct-
active ure oC ol tionmmol ance of
radiation CO2/m2/s H2O/m2/s H2O
µmol/m2/s mol/m2/s

Control variant 762 30.1 12.05 2.26 0.28

9 Biotreatments 667 30.1 4.02 1.98 0.18
o'clo with F414
ck bioproduct

Control variant 942 30.1 11.23 1.62 0.16

12 Biotreatments 849 31.8 5.00 1.10 0.07
o'clo with F414
ck bioproduct

Control variant 877 38.7 5.16 2.48 0.05

15 Biotreatments 885 38.9 1.19 1.61 0.03
o'clo with F414
ck bioproduct

From the data presented in table 2 and table 3, it results that in both analyzed
phenophases the photosynthesis process was influenced both by the climatic factors
in the area and by the substances used for the treatment of fruit trees. The
photosynthesis values were considerably lower at the F414-treated variant in almost
all times of the determinations, as compared to the control variant. The interaction
between the thermo-hydric stress and the F414 product, applied on the leaves has
led to a reduction in the carbon dioxide assimilation rate as a result of the drop in
conductivity of the stomata. In the area of sandy soils, temperatures above 35 oC
and relative humidity below 30% act as desiccant forces on plants, increasing foliar
transpiration rate [3]. In the case of leaves treated with product F414, reducing the
conductivity of stomata had a positive effect on foliar transpiration, closing of
stomata, reducing the loss of plant water.

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Table 3. Diurnal variation of physiological processes at Sprindold variety
cultivated under thermo-hydric stress conditions (September 7, 2017).
Prunus persica, Springold variety
Hour Experimenta Photosyntheti Air Photosynthe Foliar Stomatal
l variant c active tempe sisµmol transpirati conducta
radiation rature CO2/m2/s onmmol nce of
µmol/m2/s o
C H2O/m2/s H2O
mol/m2/s
Control 807 25,7 6,97 2,91 0,31
variant
9
o'cloc Biotreatment 746 26,4 3,66 1,87 0,14
k s with F414
bioproduct
Control 814 24,8 4,73 0,93 0,09
variant
12
o'cloc Biotreatment 791 26,4 3,44 1,8 0,17
k s with F414
bioproduct
Control 689 35,1 3,56 1,95 0,05
variant
15
o'cloc Biotreatment 651 35,6 7,5 2,79 0,08
k s with F414
bioproduct

60.53 60.72 56.57 57.62

Water forms and dry substance

70
60
39.47 37.28
50
40
30
%

20 3.96 5.1
10
0
Total water % Free water % Bound water Dry substance
% %

Control variant Biotreatments with F414 bioproduct

Figure 1. Water forms and dry substance from peach leaves grown under
thermo-hydric stress
Analyzing figure 1, it is noticeable that leaves of the Springold peach variety
have been subjected to severe water stress. The percentage values of total water,
free water and leaf-bound water were higher at the variant treated with F414. Of

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note is the percentage of bound water, which was 1.14% higher, indicating that
application of F414 to peach has impressed increased resistance of plants to thermo-
hydric stress. Similar research by Escobar-Gutierrez (1998) pointed out that the
moderate water stress caused the relative water content of the peach leaves to drop
from 74% to 70% and under severe water stress, the relative water content decreased
to 67% [5]. Regarding the dry substance, its highest values (39.47%) were shown
by the control variant, which is explained by the higher values of photosynthesis
recorded in the untreated Springold variety with product F414.

CONCLUSION
The intensity of the physiological processes recorded at the Springold peach
variety was influenced both by the climatic factors specific to the southern area of
Oltenia and by the phytosanitary treatments applied during the vegetation period.
Under conditions of thermo-hydric stress, with temperatures above 38 oC and
insufficient rainfall, the application of the F414 biological product led to the
formation of a hydroactive pellicle on the surface of the leaves, reducing the
stomatal conductance of H2O.
Stomata closure reduced the carbon dioxide assimilation rate, and
photosynthesis values were considerably lower in the variant where F414
biotrataments were applied. On the other hand, the percentages of the dry substance
increased directly in proportion to the photosynthesis values, being higher by 2.19%
for the control variant.
As for foliar transpiration, the F414 product had a positive effect, the pellicle
formed on the surface of the leaves, reducing the amount of water lost at the foliage
level. The application of this product has positively influenced drought resistance
of the Springold variety, the percentages of the bound water being higher (5.1%)
compared to the control variant (3.96%).

ACKNOWLEDGEMENTS
This study is part of the ADER 4.1.4. Sectoral Project "Integrated technologies
for the prevention and control of harmful organisms in agricultural and horticultural
plants with minimal consumption of resources".

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