CC BY
7
Sanaev Normumin Norberdievich, candidate of biological Sciences, Senior Researcher of the Institute of Genetics and Plant Experimental Biology, Uzbek Academy of Science, Tashkent E-mail: [email protected]
EFFECT OF THE SOIL MOISTURE CHANGES ON THE GROWTH AND DEVELOPMENT OF DIFFERENT COTTON BIOTYPES
Abstract: The article presents data on the growth and development of introgressive lines obtained on the basis of interspecific hybridization and cotton varieties differing in tolerance to water deficiency, grown in three conditions for water availability. Some physiological processes taking place in the leaves (the total water content in the leaves, transpiration rate, water-holding capacity) in the samples studied were studied. The observed differences according to the obtained data are the result of the adaptability of the studied biotypes ofvarieties and introgressive lines of the cotton plant depending on the genotype.
Keywords: cotton, introgressive lines, cultivated varieties, water deficiency, total water content in leaves, transpiration rate, water-holding capacity.
Introduction
Cotton-growing, which is one of the main agricultural branches of the republic, is based mainly on artificial irrigation and requires regular irrigation with higher degree than other crops. For the cultivation of cotton on a hectare field in our country is spending more than twice the water, compared with some countries [4]. At present, in the cotton fields together with introduction ofhigh-yielding varieties that meet world standards for quality, also creation of varieties with resistance to adverse environmental factors is important. The solution of these problems depends on the acceleration of breeding genetic work on the selection of genotypes adapted to different soil moisture conditions and work on selection of appropriate biotypes [1].
Materials and methods
As a material of the investigation were 5 introgressive lines L-384 (F12[(G.thurberi x G.raimondii) x Tashkent-1]); L-483 (F9[(G.thurberix G.raimondii) x C-4880]); L-534 (F9 [(Tashkent-6 x G.raimondii) x C-4880]); L-6 (F10 [(C-4880 x x G.stocksii) x C-4534]); L-8 (F 10[(G.thurberi x G.anomalum) x x C-4880]) corresponding to the medium-fibrous species G.hirsutum L. and different in the tolerance to the water deficiency varieties Tashkent-6 (control), Gulbakhor-2, Navbak-hor- 2, AN-Bayut-2, Bukhara-6, Omad and a new variety Ar-mugon-2. Planting was carried out on May 1-2, 2016 at the experimental station "Durmen" of the Institute. All samples were studied in the following three conditions of water supply: according to the scheme 0-1-0, i.e. single watering in the mass flowering phase (13.07.2016), soil moisture before irrigation 56.5%, 1100 m3/ha water availability - conditions of the simulated drought; according to the scheme 0-2-1 at the phase of mass flowering and at the beginning of mass box
formation (05.08.2016), as well as in the phase of opening the boxes (August 11, 2016); according to the scheme 1-3-1 during the budding phase (June 30, 2016) and the accumulation of the crop (July 14, August 05 and August 21, 2016), in the phase of opening the boxes (10.09.2016), respectively, with a soil moisture content of 70.7%; 75.2%; 72.3%; 75.8%; 70,5%, before watering and 5200 m3/ha of water supply.
For the purpose of comparative study of resistance to water deficiency during the growing season, field studies were conducted to study a number of morpho-physiological indexes. The results of the studies were statistically processed using a single-factor ANOVA dispersion using the Fisher test [5].
The results of the research and their discussion
Over the previous years, individual selection according to the shape of the bush and resistance to water deficiency were carried out [3]. Seeds of individual selections with the best indicators were divided into three parts and studied in three water-provided conditions. Comparing the indicator "height of the main stem" in the version of the irrigation scheme 1-3-1, there are marked differences in comparison with other conditions of irrigation. For example, if the height of plants in the cotton plant variety Gulbakhor-2 under this irrigation scheme was 139.0 ± 4.4 cm, for the 0-1-0 irrigation scheme it was 100.0 ± 2.8 cm, and for the 0-2-1 was 102.6 ± 4.2 cm. In the introgressive line L-384, according to the variants, it was 143.7 ± 8.1, respectively; 93.6 ± 3.4; 109.4 ± 6.4. For L-8 lines this index had the smallest value (100.7 ± 2.9, 91.2 ± 1.0, 86.6 ± 4.7 cm) and no significant differences in the amount of branching were found in comparison with other samples. The reason for this is very short nodes (2.5-3.5 cm) between the fruiting branches, which are related to the conical, first type of branching. At the
L-534 line, the plant height for all variants averaged 106.4±6.7 cm and the plants had a generally conical shape with a second type of branching. The height of plants of variety Tashkent-6 averaged 97.8 ± 2.2 cm with a branched third type of branching.
Phenological observations on the number ofleaves and leaf area showed that these indicators are dependent on the plant genotype. For example, in all variants ofthe experiment, the largest leaf area was observed in Bukhara-6 (an average of 106.8 ± ± 2.9 cm2), the lowest in Tashkent-6 (average 81.6 ± 1.9 cm2), the number ofleaves 32.7 ± 4.2 pcs. The Armugon-2 variety and
the L-6, L-8 lines had a relatively large number of leaves (45.8 ± ± 3.9 pieces) and the leaf area averaged 88.9 ± 2.5 cm2.
In some varieties and lines, there were differences in the variants of the irrigation scheme. For example, in the AN-Bay-aut-2 variety under the 1-3-1 irrigation scheme, the leaf area was 112.8 ± 1.0 cm2 and in the 0-1-0 irrigation scheme it was 85.8 ± 2.3 cm2, significant differences in the number of leaves.
It is known that the deviation from the norm of soil moisture negatively affects the physiological and biochemical processes taking place in plants [2].
Bio types
Figure 1. The total water content in the leaves of biotypes under different water availability (The letters indicate the degree of reliability of the differences between the samples (P < 0.05) in the Fisher PLSD test)
Figure 2. Transpiration rate in biotypes under different water availability (The letters indicate the degree of reliability of the differences between the samples (P < 0.05) in the Fisher PLSD test)
The trait "total water content in leaves" was high in all studied cotton varieties under the irrigation scheme 1-3-1 and in all introgressive lines under the 0-2-1 irrigation scheme. In the 0-1-0 irrigation scheme, all the samples studied showed low rates. The cotton plant variety Navbakhor-2 (59.4 ± 0.5%) and L-6 line (60.8 ± 0.5%) were especially different (Figure 1).
One of the main processes in the management of water balance in plants is transpiration. Analysis of the obtained data shows that with the variant of the irrigation scheme 1-3-1, the transpiration rate in all the samples studied was high, especially the Armugon-2 grade was significant (54.1 ± ± 5.2 g/m2 x hour). With the 0-2-1 irrigation scheme, the highest transpiration rate index was observed at the L-6 line (43.3 ± 3.8 g/m2 x hour), and the lowest index was observed in Omad (19.9 ± 2.3 g/ m2 x hour), and with the 0-1-0 irrigation scheme, this index was the smallest in all the samples studied, in Omad, Bukhara-6, Armugon-2 and L-384, L-8 lines were 12.4 ± 3.0; 15.7 ± 3.6; 19.0 ± 4.0; 18.7 ± 2.9; 18.3 ± 2.9 g/m2 x hour (Fig. 2).
One of the important indicators in the water balance of plants is the trait "water-holding capacity" of leaves. The water retention capacity of cotton leaves depends on a number of factors, including soil moisture and biological properties of the studied biotypes. The water-holding capacity of the leaves of the studied cotton samples was studied under different water conditions, this feature shows the water flow due to evaporation within 2 hours of the initial water content in the leaves. A low index of this trait indicates a high water holding capacity and vice versa, high index - low water holding capacity of the leaves.
There was a difference in the water-holding capacity of leaves of different varieties and lines of cotton under different conditions ofwater availability. If this parameter in the cotton variety Armugon-2 under irrigation scheme 1-3-1 was 32.5 ± ± 1.2%, then under the irrigation scheme 0-1-0 it amounted to 11.5 ± 1.5%, i.e. The difference between them was 21%. In the Omad variety, these figures were 17.3 ± 1.2 and 8.3 ± 1.5%, respectively. In the AN-Bayaut-2 cultivar, slight differences in this trait were found from the variants of the experiment.
Figure 3. Water-holding capacity of leaves of biotypes under different conditions of water availability (Letters indicate the degree of reliability of differences between samples (P < 0.05) according to the Fisher PLSD test)
With the 0-1-0 irrigation scheme, the highest evaporation of water in this class was observed in comparison with other cotton samples. In the variant of the 1-3-1 irrigation scheme, all introgressive lines showed high indexes, while in the 0-1-0 irrigation scheme the L-8 and L-384 lines showed a high water-holding capacity (Fig. 3).
Thus, as a result of the studies carried out, it can be concluded that with increasing in the water deficiency in the soil, the total water content in the leaves of cotton decreases with
a simultaneous decrease in the intensity of the transpiration process. On the other hand, the water retention capacity of the leaves increases. The observed differences are the result of the adaptability of the studied cotton samples depending on the genotype.
References:
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