Сельское
хозяйство/ 5. Растениеводство, селекция и семеноводство
УДК 633.63
Candidate of agricultural sciences Ionitsoy Y.S.
Institute of
bioenergetics cultures and sugar beets NAAS of Ukraine
Influence
of moisture mode on the dynamic of humidity potential of sugar beet leaves
One of the decisive factors for high productivity is soil saturation
with water. Sugar beet belongs to relatively drought resistant crops and are
much less transpiration factor than many other (130–370) [3], but prolonged
drought can cause stress in plants, resulting in significant loss of yield [4, 5,
6]. At low moisture water metabolism have changed, which index of activity is
water content of leaves tissues [2]. Adaptive response of the structural
elements of the cytoplasm (protein and water) ensures its stability and
increases the water-holding capacity of cells [1]. This changes the ratio
between free and bound water in the cells of leaves, which is directly related
to drought tolerance of plants. The aim of research was to study the influence
of soil water capacity of dynamics of total, free and bound forms of water in
the leaves of sugar beet hybrids of different origin.
Researches were conducted in vessel of Vagner diameter 21 sm., tall 35 sm.
with the volume 14,5
kg. of air-dried soil. Typical alkaline black soil was used with the following
agrochemical characteristics: humus – 3,8–4,0%, salt pH – 6,4–6,6, Hr –
1,4–1,7 mg/ equivalent for 100 g. of soil, mobile phosphorus 184–197 mg/kg ,
and potassium exchanged according to Chirikov 81–89 mg/kg of soil, alkaline
hydrolyzed nitrogen 159–163 mg/kg. The reaction of sugar beet varieties and hybrids Uladivskiy
moonseed, Ukrainian ChS 70, Extra, Roberts, KW Zbruch and humidity modes 45,
60, 76% FFM. Seeds of sugar beets planted in late April to early May. Optimal
rate of fertilizers was applied – 3,0 g. a. i. of NPK per vessel (the estimated
rate for yield 50 t/ha). Soil humidity was kept by watering the soil in vessels
by weight. The content of free and bound forms of water was determined by
refractometric method (A.F. Marynchik, 1957 in modification H.N. Pochynka,
1976). Accounting yields conducted in early October. Repetition of the
experiment is 7 times.
Research results. The analysis of research result have shown that the
total content of water in leaves of sugar beet varieties and hybrids in July little
different in different modes of moisture capacity (80,4-83,3
% crude substance), but
had the tendency to increase with increasing of water level in the soil (fig.1).
Fig. 1. Influence of moisture capacity mode
on water form content in the leaves of sugar beet hybrids of different origin
in soil in July.
The number of free and bound water, and the ratio between them varied in
different modes of moisture capacity. In the mode
45% FFM the content of free water in the plant leaves in July was 34,8–36,4%
per crude substance that inferior versions with higher modes of moisture
capacity. The minimal index was fixed for Uladivskiy moonseed 35, maximum –
Ukrainian ChS 70 Hybrid.
In this embodiment, the plants of sugar beets experienced water
shortages and used defense mechanism against stress, which manifests itself in
the growth of bound water content in cells till 44,6–46,1% per crude substance.
These figures correspond 55,0–56,9% of the water in the form of leaves and
higher than in modes with 60 and 75% FFM. With the increase of water capacity
mode till 60% FFM the increase of free water content for 5–15% and decrease of
bound water fro 4–14% was observed; and with the increase till 75% FFM – for 19–24%
and 16–20% respectively compared to the option where 45% FFM was provided.
Late July – early August is a critical period for sugar beet in relation
to moisture capacity. In this period the plants form a maximum leaf apparatus,
and lack of moisture leads to disruption of water balance and outflow of
plastic substances.
Researches have established that the rate of water content of leaves
declined in August for all variants compared to July and the total water
content was within 77,7–81,1% per crude substance (fig. 2).
Fig. 2. Influence of moisture capacity mode
on water form content in the leaves of sugar beet hybrids of different origin
in soil in August
Herewith in the mode of 45% FFM the volume of bound water increased till
55,8–58,0% in crude substance with the maximum index for Ukrainian ChS 70 and
minimal for Roberta hybrid. Improving of moisture capacity mode till 60% FFM contributed the increase of free water
content till 25,0–27,3% and the
decrease of bound water till 52,8–55,3% per crude substances. Providing ground with
water at the level of 75% FFM had beneficial effect on plants in August, as
evidenced by a decrease in the content of bound water in the leaves (48,6–49,7%
per crude substance) comparing to modes 45% and 60% FFM.
Ratio of free and bound water in the leaves of different sugar beet varieties
and hybrids in August differed in various options of moisture capacity and with
the increase of water rate from 45% to 75% FFM was averaged by: 1:2,6; 1:2,1;
1:1,5.
In general, in August there was an increase of bound water content for
the sugar beet leaf by 20–30%, compared to July in all modes of moisture
capacity.
An analysis of the research results shows that the water content of
leaves in September in the mode 45% FFM was within 76,7–78,3% and in the modes
60% and 75% FFM increased till 80,0–82,0% per crude substance (fig. 3)
Fig. 3. Influence of moisture capacity mode
on water form content in the leaves of sugar beet hybrids of different origin
in soil in September
The content of bound water in the leaves culture decreased compared with
August in all options. With minimal moisture capacity of soil the content of
bound water in plant leave was at the level of 53,3–54,5% per crude substance.
With the increase of humidity level till 60 and 75% FFM the content decreased
till 51,2–53,7 and 45,7–49,5% per crude substance respectively, that indicates
the decrease of intensity and deepness of stress with increasing of water in
the soil.
Total water content in leaves of plants of different sugar beet
varieties and hybrids was the highest in July in all modes of moisture capacity
– 80,4–83,3% per crude substance, and in August and September it decreased
slightly till 76,7–82,0%. For the middle of August the accumulation of bounded water
by plants of the studied sugar beet varieties and plants was observed, that
indicates the presence of stress in plant. By providing 75% FFM the content of
bound water in the leaves of sugar beets in this period increased comparing to
the modes 60 and 45% FFM respectively.
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