MORPHOLOGICAL CHARACTERS VARIABILITY OF THE A4-10 WINTER WHEAT LINE UNDER CURRENT CLIMATE CONDITIONS

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The purpose of cultivating the plant is the production of grains (Tester and Langridge, 2010), mainly used to obtain bread (Curtis et al., 2002).The content of grains in nutritional elements is diverse and balanced, having a special importance in human nutrition (Li et al., 2014).
Thus, wheat is considered one of the most genetically diverse cereals (Charmet et al., 2005).In the characteristic expression of all the characters and especially the morphological ones, an important role is played by the climatic evolution during the vegetation period.
Under normal conditions in the resort area, new wheat lines with improved characters show relative constancy over the years.With the emergence of the phenomenon of global warming, nature brought out the accents of drought, namely in certain periods in the vegetation of the plants.
The intensity of drought periods usually demonstrates the negative influence on the morphology of new wheat lines, including the A4-10 line.For this A4-10 line, which is in a pre-homologation period, it was sought that through the study of some morphological characters in three different years, some aspects of adaptation to the current climatic conditions could be ascertained.

MATERIAL AND METHODS
The new line A4-10 of winter wheat was cultivated during 2020-2022 in an experience of the type of comparative cultures, specific into a breeding field from Agricultural Research and Development Station from Pitești.Sowing was carried out between October 5-10, with a density of 550 grains per square meter.Fertilization was done at the level of N80 P60.At full maturity, 25 stems were chosen according to the zig-zag method, in four repetitions.The stems were cut in the field and brought to the laboratory, where a series of determinations were made.These included: straw length, basal internode thickness, the length and weight of the ear, the number of spikelets in the ear, the length of glume, palea and awn, the number of grains in an ear and their weight, mass of a thousand grains (MTG) and grain dimensions: length and thickness.
These morphological characters were further analyzed by several methods.Thus, on the one hand, the method of class intervals was used.The graphic representation of these intervals was carried out with the help of the Excel program.
The obtained class intervals expressed modal values on the one hand, and the limits of the variability intervals on the other.
Simple correlations by Excel program, were established between all the analyzed characters, with the help of which some trends could be observed.
From a statistical point of view, the obtained data were processed by the variance analysis method.Statistical parameters were calculated using the formulas: ā = !"

RESULTS AND DISCUSSION
In general, the cultivation area from Agricultural Research and Development Station from Pitești has a favorable climate throughout the entire period from the beginning of vegetation to flowering (table 1).Precipitation that falls during the autumn period usually ensures optimal emergence and twinning.The rains that fall in the spring and until the maturity of the wheat should be favorable, which would lead to the normal morphological manifestation of each individual genotype.
On the other hand, however, this continuous favorable rhythm began to be increasingly fragmented by periods, either with some excesses or with drought (Watson et al., 2021).The drought can thus become quite prolonged.
In these conditions, the A4-10 line reacted specifically from a morphological point of view, with certain trends (Farooq et al., 2014).Knowing them could define certain degrees of tolerance and even the resistance of the respective line to the climatic stresses (drought) that have been taking place lately (Fang and Xiong, 2015).
On the other hand, the comparison between the potential evapotranspiration, PET, and the rain regime in the wheat vegetation highlights the possibilities that the plant had both in the formation of the plant habitus and of the respective production elements (Dolferus et al., 2011).The closer the total amount of precipitation came to required, consumption, the better the favorability in that year.
Of the three years analyzed, 2020, after a normal autumn, followed the spring characterized by a lack of precipitation.The months of March and April ensured the growth of the plants, and in May and June the rainfall favored flowering and the deposition of nutrients in grains.
The temperature regime approached normal, exceeding the average by 1,54 0 C in total.This year an important peak was noted in June, which contributed to the formation of some morphological characters of the plant in general and of the ear, namely at high levels.
2021 started well with rains in the young vegetation.The situation was also maintained in the second part of the vegetative cycle, when the A4-10 line had rainfall closer to what was needed until maturity, which ensured a good level of grain formation (Farooq et al., 2014).This year's temperatures have been close to normal.
In the last year 2022, the amounts of water that fell for the first period were closer to what was needed.Instead, in the second part of the vegetation, the conditions were characterized by drought, which affected the deposition of nutrients in the grains (Manschadi et al., 2006;Dai, 2013).
In conclusion, the first year of cultivation had better favorability, and the following two years had relatively lower degrees of favorability.
From the figures 1 and 2, lower strain values characterize the new creations, as is the A4-10 line, obtained for intensification conditions.The measurements showed that in the three years of cultivation, the straw of this new winter wheat line was between 40 and 80 cm.The 55-60 cm straws had the dominant frequencies, very close in the three years (figure 1).With this character, the A4-10 line can be considered to meet the qualification of both advanced and intensive.
The diameter of the basal internode had modal values at 3.1 mm, and the limits of this character were between 2.2 mm and 5 mm (figure 2).The appearance and ear sizes of this wheat line were characteristic.Thus, its length had dominant values of 10 cm in years with sufficient precipitation and 8-9 cm in the last year (2022).In general, its variability was between 7 cm and 13 cm (figure 3).The biomass of the analyzed ears was generally between 1 g and 6 g (figure 4).Modal values expressed weights of 2.5 g in the first year, 3 g in the second year and only 2 g in the last dry year.The number of spikelets formed in each ear of the A4-10 line had a morphological importance in the expression of spikelet values.Thus, in the three years between 12 and 28 spikelets were formed/spike.Modal values were at 22 spikelets in the first crop year, 18 spikelets in the second year and only 16 spikelets in the last dry year (figure 5).The appearance of the A4-10 line in the post-flowering period is shown in figure 6.
The grains formed according to the climatic favorability, expressed by the amounts of precipitation distributed during the growing months.Their number fell within a relatively wide register, namely between 20 and 100 from a spike of the A4-10 line.Higher frequencies were obtained at 60-70 grains/ear in the first two years and only 40 grains in the dry year (last year) (figure 7).
The weight of these grains generally followed the same mode of expression due to the different favorability of the three years of culture.The limits of variability over the entire researched period were between 0.5 g and 4.5 g (figure 8).The ears dominated, whose grains weighed 2-2.5 g in the first two years and 1.5 g in the dry year 2022.The grain sizes also had some characteristics.Thus, the length of the grains was generally comprised (interval of the three years) between 4.5 and 8 mm.In the first two years the dominant grains measured 6.5 mm, while in the last year the grains dominated with lengths of 7 mm (figure 9).The grain thickness was between the general limits of 2.4 mm and 4 mm (figure 10).The modal value for the entire period was 3-3.2 mm grain thickness.
The thousand grain mass (TGW) or mass of thousand grains (MTG), showed some differentiation according to the favorability of the three years of cultivation.In general, the values were between 20 and 55 g (figure 11).The dominant values were 45 g in the more favorable years and only 40 g in the dry year 2022.
The present data demonstrate that the A4-10 wheat line formed grains with high absolute biomass, a positive premise for its productive performance (figure 12).
From the table 2, in the first year, negative correlations were obtained between straw length and most other characters of the wheat line.The explanation could lie in the existence of the "short straw" character obtained through the activity.Between the other characters of this year the correlations were totally positive, with some significant accents between the ear characters (length and thickness), between the spikelet membranes and the grain characters (number, weight, dimension and absolute mass).From the data obtained, a slightly higher degree of climate favorability was found for the A4-10 line.In the second year of research, the obtained correlations demonstrated almost entirely positive situations.The negative exceptions were on the one hand between the length of the straw with the length of the spike and that of the length of the stalk, and on the other hand between the number of spikelets with the thickness of the grains and with their absolute mass.
Overall, the two experimental years demonstrated the manifestation of characters in which the climatic factor was relatively favorable.
In the third year, the correlations obtained were more inconstant, mainly due to the existence of accentuated periods of drought, expressed by an important deficit in the water factor.
The results obtained in the morphological analysis of some characters in winter wheat showed specificity (table 3).The length of the straw of the period 2020-2022 measured 54-61 cm.Variability demonstrated small to medium coefficients.
The thickness of the internode at the base was 3.22-3.39mm (12-20% variation).From these data it appears that this wheat line has medium to small maturity, suitable for intensification.
The length of the spike was 8.38-9.90cm, with medium variability.The weight of the ears was 2.01-3.30g, but with a high variability.The number of spikelets was 16-19.7 (11-16% variability) (table 3).
The number of grains formed in an ear was 41-59 with high variability.The weight of the grains in one ear was 1.53-2.45g, also with high variability.The grains had an average size of 6.2-6.8/3.02-3.08 mm.The variability of grain sizes was small (below 10%).
The mass of one thousand grains was on average 37.5-41.1 g with medium variability.

CONCLUSIONS
The new winter wheat line, A4-10 was recently grown during three different climatic years: the first two moderately favorable years and the third totally unfavorable year, with dry periods.
The morphological characters expressed in these conditions were specific.Thus, the stem/straw had similar dominant lengths of 55-60 cm.The thickness of the basal internode was 2.2-5 mm, which also shows a good resistance in the field of wheat, especially in the favorable climatic year.
The 7-13 cm long spike weighed 1-6 g and is characterized as medium to long and heavy.The number of spikelets in an ear was between 12-28.The parts of the spikelet: 9-10 mm glume, 10 mm palea and 6-8 cm awn describe specific characters of the newly studied line.
The number of grains in one ear was from 40 in the dry year and 60-70 in the favorable years, with the weight of 1.5-2.5 g.It revealed a new line of wheat with high production capacity.
The mass of one thousand grains was 40-45 g and is considered medium to large.The grains with dimensions of 6.5-7 mm long and 3-3.2 mm thick describe medium characters.Simple correlations were established between all the characters studied, with some differences.The correlations between the spike characters were very significant positive, which demonstrates the high productive possibilities that this variety has even in years with periods of drought.
The straw characters were highly negatively correlated with the other characters and are explained by the genetic improvement obtained by reducing the size of this variety.
The statistical indicators studied demonstrated a new line of wheat with small to medium bearing, with medium to long ears, sufficiently compact, with many grains and with their absolute weight exceeding 45-50 g in favorable climatic years.Grains like these, with more than 50 grains in the ear, with an average weight of up to 3 g describe a new, productive variety with negative tendencies in drought periods.

Table 1 .
Climatic factors evolution from winter wheat vegetation

Table 2 .
Correlations between the main characters of wheat A4-10 line plants

Table 3 .
Statistical indices for plant morphological characters of new wheat A4-10 line