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51
AGRICULTURAL BIOLOGY, ISSN 2412-0324 (Eng» ed. Online)
2015, V. 50, № 5, pp. 600-610
(SEL’SKOKHOZYAISTVENNAYA BIOLOGIYA) ISSN 0131-6397 (Russian ed.
v_____________________________________' ISSN 2313-4836 (Russian ed. Online)
UDC 633.15:631.52:581.132:58.084:535.24 doi: 10.15389/agrobiology.2015.5.600rus
doi: 10.15389/agrobiology.2015.5.600eng
MAIZE (Zea mays L.) INBRED LINES AND HYBRIDS OF SERBIAN SELECTION WITH HIGH EFFICIENCY OF PHOTOSYNTHESIS, RICH IN PIGMENT CONTENT AND INCREASED NUTRITIVE VALUE
Ch. RADENOVICH1- 2, N. DELICH1, M. SECHANSKY1, Zh. JOVANOVICH1,
G. STANKOVICH1, A. POPOVICH1
Maize Research Institute, Zemun Polje, ul. Slobodana Bajicha 1, 11185 Belgrade-Zemun, Serbia, e-mail [email protected];
2Faculty of Physical Chemistry, University of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia Acknowledgements:
Financially supported mainly by the Maize Research Institute, Zemun Polje, Belgrade and partly by the Ministry of Education, Science and Technological Development of the Republic of Serbia (Projects 03E211, 03E22, Tr-20003, TR-20007, TR-20014, reference number 31028 and 31037).
Received December 23, 2014
Abstract
This paper presents results of several different studies that confirm the hypothesis that maize inbred lines rich in proteins and with exceptional nutritive values can be bred. This is also supported by a medicinal standpoint of programmed need for maize-based food and feed. With such an experimental approach, the maize inbred lines ZPPL 146 and ZPPL 159 and hybrids derived from them (ZP 633, ZP 735 and ZP 737) rich in proteins have been systematically tested. Based on concrete results the following we can be conclude as follows. Selected maize inbred lines ZPPL 146 and ZPPL 159, rich in carotenoids, yellow pigments, also have significant amounts of other relevant bioactive compounds. Observed inbred lines have erect top leaves and are classified into a group of maize inbreds with significant properties of the photosynthesis model, are resistant to high temperatures and tolerant to drought. Spectral bands pointing to conformational characteristics of molecules of carotenoids but also of other compounds (phosphates, glutens and amides III) were established by the resonance Raman spectroscopy method applied to the leaf of the maize inbred line ZPLL 146. Physiological, biochemical and biophysical traits of elite maize inbred lines and their hybrids were observed in this study with a special emphasis on their efficiency of photosynthesis, productivity and suitability for broad use of nutrient values of grain and other essential biogenic matters, first of all pigments that express antioxidative properties. Relevant traits, properties and parameters of observed maize inbred lines that can be used in the process of selection are presented. These prestigious maize inbred lines were used to develop high-yielding and high-quality maize hybrids (ZP 633, ZP 735 and ZP 737) that are recognisable for their quality in human nutrition (children and the elderly), that are confirmed by medical observations related to their use in food and feed. Relevant agronomic and morphological traits of maize hybrids are presented. Moreover, results on grain structure and yields obtained in the regions of southeastern Europe are also displayed.
Keywords: maize (Zea mays L.), inbred lines, hybrid, thylakoid membrane, photosynthetic model, delayed chlorophyll fluorescence, pigment properties, nutritive value.
The period since 1954 to date is historically significant due to numerous accomplishments in maize breeding and selection of maize hybrids and the production of hybrid seeds of high quality. As a result of such activity there are more than 1,400 developed grain and silage maize hybrids as well as hybrids for the industrial processing [1-4]. During this period, up-to-date technical and technological prerequisites for the modern process of breeding, the production of hybrid seeds and sufficient amounts of commercial seeds, have been provided [59]. Certainly, diverse interdependent studies of several scientific disciplines (biophysics, biochemistry, biotechnology, photosynthesis and Raman spectroscopy) were intermingled into the complex of developmental trends with the aim to modernise and efficiently implement contemporary programmes in maize breed-
ing and seed production [10-16] In addition to the exceptional results obtained in breeding of standard maize hybrids for grain, silage and industrial processing, there was the need to develop elite inbred lines and quality maize hybrids with improved chemical composition of essential biogenic compounds [17-22].
To meet many demands and justifiable needs for quality nutrition of people (mainly children and the elderly), domestic animals, as well as for industrial processing (semi- and final products) it was necessary to select maize inbred lines with significantly richer pigment-complex properties and the exceptional nutritional value. With such inbred lines it was possible to develop high-quality maize hybrids, which would meet established medicinal criteria regarding healthy nutrition of people, domestic animals, as well as broadly developed industrial processing.
The purposes of the present study were to compare physiological, biochemical, biophysical features of the maize elite inbred lines and their hybrids, to assess the effectiveness of plant photosynthesis, productivity and suitability for wide practical use, nutritive value of grain and accumulation of essential biogenic substances, in particular, pigments, possessing high antioxidant activity.
Technique. The studies were performed with two elite maize inbred lines, ZPPL 146 and ZPPL 159, and the hybrids ZP 633, ZP 735 and ZP 737 developed from them. The observed maize inbreds and hybrids belong to the collection of the Maize Research Institute, Zemun Polje, Belgrade, Serbia.
Methods applied to determine the grain chemical composition of maize inbred lines and hybrids are generally accepted and standardised and already described in detail in previous papers [17, 22-26]. The resonance Raman spectroscopy of maize inbred line leaves were done in accordance with the procedure and the method described in our previously published manuscripts [27-30]. The angle and the leaf area of maize inbred lines estimation was related to studying the erect position of top leaves in maize inbred lines. A specially designed protractor was used to measure the angle between the position of the above-ear leaf and the position of the plant stalk on maize inbred lines. The leaf area was measured by the LI-3000 portable leaf area meter (LI-COR Biosciences, USA). Measures of the angle between the above-ear leaf and the stalk and the leaf areas were carried out on 126 plants for each inbred line during the three-year period. These procedures had been described in previously published papers [15, 26].
The series of the experiments was related to photosynthetic-fluorescence measurements, including thermal processes of delayed chlorophyll fluorescence (DF), critical temperatures of phase transitions and activation energies. The test maize inbreds were grown in the experimental field of the Maize Research Institute, Zemun Polje. These inbreds were brought to the laboratory between 7 a.m. and 8 a.m. Plants sampled in the field were transversally cut in the ground internode. In the laboratory, plants were placed in water up to the second internode. Prior to the fluorescence experiment, all plants were kept under the black ball glass for two hours. A segment of intact above ear leaves was taken from such plants and placed into a chamber of the phosphoroscope. The intact leaf segments were kept in the chamber (in the dark) for at least 15 minutes, and then thermal processes of DF were measured. These tests were performed on 118 plants of each maize inbred line. An improved, non-invasive photosynthetic-fluorescence method was applied for these measurements. This method was developed at the Maize Research Institute.
The equipment for measurement of chlorophyll DF has been already described in the previously published papers [12-14, 26, 31-33]. However the device for recording of thermal induction processes of chlorophyll DF, critical
temperatures of phase transitions and activation energies is much different and has been described in detail in the previously published paper [33]. The distinctive components of this devise are thermistors, embedded in the phosporoscope, i.e. the dark chamber, and a temperature controller PRT 3000 (Sefram, France). The temperature controller maintains a constant, preset temperature of the sample (leaf segment) or it changes the temperature within the range of 25 °С to 60 °С at a predetermined time interval, while the thermistor in contact with the surface of a leaf segment provides the accurate temperature measurement.
Numerous and long-term studies of yields (t • ha-1) of the three high-yielding and high-quality grain and silage maize hybrids (ZP 633, ZP 735 and ZP 737) were performed in many different locations in Serbia and other countries of south-eastern Europe. Standard methods for contemporary maize production, tinning and processing were applied in these studies [17, 20, 34].
Data obtained were processed statistically using relevant software.
Results. Empirical efforts to acquire knowledge about the need for maize diet in human nutrition were initiated a long time ago, perhaps 200 years ago. Much later, in the 1950s, scientific literature related to this topic emerged, primarily in medicinal institutions. However, the authors of this study became inFig. 1. Actual appearance of elite maize (Zea mays L.) inbred lines with erect top leaves: ZPPL 146 (A) and ZPPL 159 (B), and ears of high-quality hybrids ZP 633 (C), ZP 735 (D) and ZP 737 (E) of Serbian selection.
As these are inbred lines with significant breeding traits and specific chemical properties and maize hybrids (Fig. 1) with their use programmed for nutrition of people, domestic animals and for industrial processing, their traits will be separately presented in this manuscript. Note, comprehensive studies of the elite inbred lines and hybrids with erect top leaves developed from these inbreds encompassed several series of experiments in which both conventional and new own modern methods were applied.
terested in this topic in the early 1990s
1. Chemical composition of grain in maize (Zea mays L.) elite inbred lines and hybrids of Serbian selection (an average for 3 years, trial field of Maize Research Institute, Zemun Polje, Beograd, Serbia)
Published data (24) Average grain chemical composition
Parameter range average lines hybrids
ZPPL 146 |ZPPL 159 ZP 633 ZP 735 | ZP 737
Moisture, % 7-23 16.0 10.24 10.12 9.90 9.84 10.15
Starch, % 61-78 71.7 67.80 66.26 68.23 64.39 67.86
Protein, % 6-12 9.5 10.22 12.57 11.11 12.27 11.57
Fat (oil), % 1.0-5.7 4.3 7.53 5.38 6.11 5.82 7.16
Ash, % 1.1-3.9 1.4 1.48 1.45 1.51 1.54 1.47
Ash, % 3.0 2.26 2.33 2.37 2.43 2.00
Pentose (ribose and
desoxyribose), % 5.8-6.6 6.2 - - - - -
Fibres, % 8.3-11.9 9.5 - - - - -
Cellulose + lignin, % 3.3-4.3 3.3 - - - - -
Total sugars (as glucose), % 1.0-3.0 2.6 - - - - -
Continued Table 1
Raman frequency, snr1
Fig. 2. Resonance Raman spectrum of the leaf of the maize (Zea mays L.) elite inbred line ZPPL 146 of Serbian selection.
Yellow pigment, ggpCE/g
d.m. - - 19.00 18.10 27.30 21.90 21.60
Total carotenoids, mg/kg 12-36 26 33.2 31.8 32.4 28.3 27.8
Note. Yellow pigment assessment (d.m. mrans dry matter) was done by the AACC method: AACC (Amer.Assoc. of Cereal Chem. USA), 1995. Pigment. Methods 14-50 [25]. Dashes mean low influence of the rest parameters on nutritive value in the inbred lines and hybrids.
Results on overall studies of grain chemical composition of observed maize inbred lines and hybrids are presented in Table 1. Obtained results relate to important chemical constituents and are supplemented with results of chemical compositions of vitamins, dietary fibres and other biogenic and medicinal compounds [24, 25].
This paper presents a typical example of a leaf resonance Raman spectrum of the maize inbred line ZPPL 146, i.e. a carotenoid molecule placed on a non-polar phase of a thylakoid membrane (Fig. 2).
The following six characteristic resonance Raman spectral bands were established within the 9001800 cm-1 interval of Raman frequencies: 962, 1026, 1160, 1187, 1206 and 1520 cm-1. Four spectral bands with smaller intensity (I926, I1026, I1187, I1206) were caused by conformational changes of phosphates, glycogens, amides III. The remaining two spectral bands with a significantly higher intensity (I1160, I1520) are regularly analysed in relation to the conformational changes in the carotenoid molecule. It is common to analyse the differences in the intensities of spectral bands (I1520 and I1160), and even more often to analyse the differences in their ratio (I1520/I1160). Figure 2 presents the resonance Raman spectrum of the leaf of the inbred line ZPPL 146 with dominant spectral bands (I1520 and I1160) that condition the carotenoid molecules placed in the non-polar phase of the thylakoid membrane of the leaf of the inbred line ZPPL 146. In this paper, the effort was made to emphasise the application of resonance Raman spectroscopy in studying important vital functions of leaves of maize inbred lines, especially under agroecological conditions atypical for the maize growing region. Carotenoid molecules (p caroten, C40H56, with the activity of vitamin A, but also two xanthophylls: cryptoxanthin C40H56O and zeaxanthin C40H56O2), since localised in non-polar phase of the thylakoid membrane of maize inbred leaves, showed to be a very suitable natural probe, capable to contribute to registering not only higher and more significant, but also smaller and finer conformational changes. These changes in the molecular structure of carotenoids may be expressed in the form of bending, stretching, compressing and physical disruption of chemical bonds, which is caused by intensive actions of environmental factors, first of all of unfavourable critical temperatures. In the end, each conformational change in the carotenoid molecule unconditionally changes the function not only of the carotenoid molecule but also of the thyla-koid membrane in leaves of maize inbred lines. Conformational changes in chemical bonds -C=C- are reflected in the spectral band at 1520 cm-1. In addition, conformational changes in chemical bonds =C-C= are reflected in the spectral band at 1160 cm-1 (Fig. 2) [36].
Results on the measures of angles between the above-ear leaf and the stalk, as well as, the average leaf areas are presented in Table 2. Based on obtained results on the measures of angles it can be stated that the observed maize elite inbred lines belong to the group of recently developed inbred lines with erect top leaves and a trait of a photosynthetic model.
2. Angle between the above-ear leaf and the stalk and the leaf area in maize (Zea mays L.) inbred lines of Serbian selection with efficient photosynthesis (an average for 3 years, trial field of Maize Research Institute, Zemun Polje, Beograd, Serbia)
Line FAO maturity Heterotic origin of inbred line Angle of the above-ear leaf, ° The above-ear leaf area, sm2
group X G X G
ZPPL 146 650-700 BSSS, USA, Zemun Polje 20.8 1.21 3762.7 238.00
ZPPL 159 550-600 Local population from Argentine (S13) crossed to the inbred PE25-10-
1, Zemun Polje 21.3 1.23 2378.1 241.00
Note. Observed maize elite inbred lines represent good heterotic pairs, have good combining abilities for grain yield and silage, their propagation is well and they are highly yielding inbreds. These inbreds are rich in pigments and have extraordinary nutritive qualities (for detail see Table 6).
The experimental measures of changes in the stationary level of delayed chlorophyll fluorescence (Idf) in dependence on the temperature, ranging from 25 to 60 °С, were performed. The dynamics of temperature dependence for observed maize inbred lines is presented in Figure 3 (A, B).
Fig. 3. Dynamics of the intensity of the delayed chlorophyll fluorescence (Idf) of thermal processes in dependence on the effects of temperatures in chloroplasts and the thylakoid membrane of the intact above-ear leaf of the maize (Zea mays L.) elite inbred lines of Serbiam election with erect top leaves: ZPPL 146 (A) and ZPPL 159 (B).
A В
t,°C
32 34 36 38 40 42 44 46 48 50 52 54 56 58 60 30 32 34 36 38 40 42 44 46 48 50 52
4 2|.......................................................I 4 g I......................................................
2.6- ......... 2.8-
20400328 0.00323 0.00318 0.00313 0.00308 0.00303 ^00330 0.00325 0.00320 0.00315 0.00310
l/T X К)-4, K1
Fig. 4. The Arrhenius plot for the determination of critical temperatures (in Kelvins) and conformational changes in chloroplasts and thylakoid membranes of the intact above-ear leaf of observed maize (Zea mays L.) elite inbred lines of Serbian selection with erect top leaves: ZPPL 146 (A) and ZPPL 159 (B).
The Arrhenius plot is based on the linearisation of the DF temperature dependence of observed maize inbreds. Critical temperatures (phase transition temperatures) at which conformational changes occur in chloroplasts and the thylakoid membrane are determined by the application of the Arrhenius plot. Results of the Arrhenius plot application to observed new maize inbred lines are
presented in Figure 4 (A, B).
Detailed studies of the thermal processes of DF, and especially of the analysis of the experimental thermal curve, encompassed not only the temperature dependence and the Arrhenius plot, but also the estimation of values of activation energies (Ea) for critical temperatures (phase transition temperatures) in chloroplasts and the thylakoid membranes of the observed maize inbreds with erect top leaves: ZPPL 146 (A) and ZPPL 159 (B). Obtained results are shown in Table 3.
3. Changes in activation energies (Ea expressed in kJ/mol) and critical temperatures tpt (phase transition temperatures expressed in °С) in the thylakoid membrane of the intact above-ear leaf of observed maize (Zea mays L.) elite inbred lines of Serbian selection with erect top leaves
ZPPL 146 | ZPPL 159
Ea tpt Ea tpt
— 34.5 - 32.5
41.00 46.0 42.10 37.0
74.86 56.5 101.20 47.5
50.70 59.5 6.20 49.0
225.50 - 81.10 51.0
255.00 -
Note. Dashes mean no calculation for initial and final values for delayed fluorescence.
Thus, theoretical data and the results of biophysical experimental investigation of pigments and thylakoid membranes in leaves, in particular, the delayed fluorescence of chlorophyll and phase transition in chloroplasts and thylakoid membranes) showed high adaptive potential in studied inbred lines at heat and drought conditions.
The same high-yielding and high-quality features were characteristic of maize hybrids ZP 633, ZP 735 and ZP 737 produced from the inbreed lines ZPPL 146 and ZPPL 159 that was shown in the field trials in different territories of the south-east Europe (Table 4). In these, the results also evidenced of functional relationship between yielding and specific character and adaptive potential of photosynthetic complex in ZP 633, ZP 735 and ZP 737 plants and their morphology which is in accordance with a model of effective photosynthesis. Their important agronomic and morphological traits of ZP 633, ZP 735 and ZP 737 hybrids are presented in Tables 4 and 5.
4. Agronomic traits of observed high-quality maize (Zea mays L.) hybrids in field trials
Trait, territory of growing 1 ZP 633 I ZP 735 I ZP 737
Hybrid designation SC SC SC
FAO maturity group 550-650 750-850 750-850
Plant height, sm 250 280 290
Ear height, sm 120 130 135
1000-kernel weight, g 380 370 370
Kernel type Sowing density of silage hybrid, Semi-dent Dent Dent
x 103 plants • ha 1 60-70 70-75 70-75
Leaf position on plant Semi-erect to erect Semi-erect to erect Semi-erect to erect
Tolerance to drought Good Good Good
Tolerance to diseases Good Good Good
Leaf appearance at harvest Stay-green Stay-green Stay-green
Hybrid silage yield, t • ha-1 60-65 70-80 70-80
Hybrid grain yield, t • ha-1 7.819a 8.108b 12.732b
Hybrid growing regions’ altitude, m 300-400 250-400 250-400
Note. SC — Single Cross. Hybrid yield achieved in 30 locations in Serbia in the 2008-locations in Greece in the 2006-2009 period (b). -2011 period (a) and in 6
According to data presented in Tables 4 and 5, observed hybrids belong to long-season hybrids with modern architecture and the stay-green trait. Moreover, more than 50 % of grain of these hybrids is in the silage mass, which is
very important for silage quality. Also, the embryo content in grain amounts to above 10 %, which is especially important for quality of nutritive values of hybrids in nutrition of people (especially of children and the elderly) but also in nutrition of domestic animals, as well as for industrial processing of semi- and final products.
5. Ear morphological traits with a grain structure in observed high-quality maize (Zea mays L.) hybrids of Serbian selection
Parameter I ZP 633 ZP 735 | ZP 737
Grain moisture, % 18 19 20
Ear length, sm 22 25 25
Ear weight,g 252.30 286.42 226.70
Rows per ear 16 18 18
Kernel number 700 800 850
Масса зерна на початке, g Rate per ear, %: 228.36 248.35 200.40
grain pericarp 5.32 6.55 4.60
grain embryo 11.28 12.06 10.70
grain endosperm 83.40 81.39 84.70
Note, the maize hybrids ZP 633, ZP 735 and ZP 737 are mainly indented for grain and silage production under agroecological conditions of southeastern Europe. They are mostly used in the human diet and in nutrition of domestic animals, and to a significantly smaller extent in industrial processing and in the production of semi- and final products.
Studied maize elite inbred lines ZPPL 146 and ZPPL 159 have been broadly used in breeding for the last 5-6 years in Serbia. Moreover, they are widely used in Greece, Macedonia, and in part in Turkey and for south of Bulgaria. For these reasons, relevant observations of their total traits, performances and parameters are presented in Table 6.
6. Summary of significant breeding and seed production traits of effectively photo-synthesizing maize (Zea mays L.) elite inbred lines of Serbian selection
Trait ZPPL 146 ZPPL 159
Heterotic origin BSSS, USA, Zemun Polje Local population from Argentine (S13) crossed to the inbred PE25-10-1, Zemun Polje
FAO maturity group Grain yield at 14 % moisture, kg • ha-1: 650-700 550-600
dry land farming3 3,500 2,000
irrigationb Number of plants at harvest, per ha: 5,000 3,000
dry land farming 50,000 50,000
irrigation 60,000 60,000
Stalk properties Stalk is moderately high with prolific trait. Stalk is short. Tassel has closed side Tassel has elongated central branch with branches that shed long fewer side branches
Stalk resistance to lodging Inbreds are resistant to lodging
Erect position of above ear < 20.8° (first leaf) < 21.3° (first leaf)
leaves < 17.9° (second leaf) < 15.3° (third leaf) < 18.1° (second leaf) < 15.4° (third leaf)
Stay-green phenotype Leaf did not remain green until harvest Leaf remained moderately green until harvest
Stress tolerance Inbreds are tolerant to drought and high temperatures
Kernel traits Semi-dent type, orange kernels, while cob is white Semi-flint, orange kernels, while cob is red
Grain moisture at harvest, % 20-25 20-25
Dry down rate in the stage of Dry down rate is fast, but hybrids are Dry down rate is not fast, but hybrids are
grain maturing suited for silage suited for silage
Harvest type Hand or machine harvest is easy
Seedling Inbred emerges well
Early growth Early growth is moderate
Suitability for nutrition of Grain is suitable for nutrition of ruminants, nonruminants,
ruminants and nonruminants human nutrition and for industrial processing
Continued Table 6
Carotene content 33.2 mg/kga 31.8 mg/kga
in grain 19.0 ig pCE/g d.m.b 18.1 ig pCE/g d.m.b
Suitability for developing silage hybrids Inbreds are very suitable for developing silage hybrids
Digestibility of the hybrids Hybrids developed from this inbreds have good digestibility of the whole plant
developed______________________ and of milled grain
Note. Carotene content is indicated for dry land (a) and irrigation (b).
When discussing maize breeding, it must be mentioned that the role of maize as healthy food is still underestimated. Maize is one of the potential energy sources. It contains very little fats, and at the same time, many carbohydrates. One maize ear contains 80-100 calories. Moreover, maize contains many plant fibres and therefore it lowers the levels of blood cholesterol and blood sugar, which lowers the risk of colon cancer [37]. Nevertheless, one should pay attention to allergy attacks as maize is one of the most common allergens. Maize provides vitamins C and B, folic acid and magnesium, which positively affects brain functioning. Phosphorus is essential nutrient for bones, while potassium is necessary for the regular functioning of individual cells in the organism. It is known that excessive levels of some amino acids might cause heart diseases [37, 38]. This condition occurs due to the lack of folic acid in the organs. For these reasons, the use of maize in the diet results in successful protection of the heart. In addition, folic acid is essential for the proper foetal nervous system development, hence maize is recommended for diets of women who intend to become pregnant, as well as pregnant women in the first three months of their pregnancy. In any form maize is very beneficial for normal growth and development and metabolism functions [39, 42]. Beside the stated, the most often medicinal benefits are based on the role of carotenoids. They protect plants from damages caused by photo-induced free radicals. Carotenoids, as precursors to horomones of abscisic acid, give kernels the yellow colour [39, 42]. It is important to point out to a special role of carotenoids as antioxidants in prevention of cardiovascular diseases, cancer and cataract.
As already said, for the last 60 years, a great success has been achieved in maize breeding and the production of high-quality foundation, hybrid and commercial maize seed. Since 1978, thanks to the maize breeding programme the number of plants per area unit has been significantly increasing. This maize breeding programme was referred to as a «plant density» programme and it further directly affected the yield increase of high quality foundation and hybrid maize seed as well as commercial seed [12, 13, 40]. Somewhat later, a programme on the development of maize inbred lines with erect top leaves (inbreds with efficient photosynthesis) was established. In 1998, it was considered that these inbreds were the closest to the proposed efficient photosynthetic model. Almost at the same time, a programme on the development of maize inbred lines rich in pigments and with other chemical properties and extraordinary nutritive values was established [7, 11, 19, 21-22, 37-39].
This study was an attempt to answer the following questions by using different tests and analyses: is there a reliable and dominant trait (one or more) of observed maize inbred lines rich in the pigment complex that would be the basis for the development of new high-quality maize hybrids that would be suitable for food, feed and industrial processing of semi- and final products? The analysis of presented overall results, obtained in the series of experiments, can easily give the positive answer to this question. Consequently, maize elite inbred lines (ZPPL 146 and ZPPL 159) and high-quality hybrids developed from them (Zp 633, ZP 735 and ZP 737) are the best confirmation of the stated. Selected inbred lines and hybrids developed from them are rich in pig-
ments, have significant nutritive values, especially of carotenoids that give kernels their yellow colour [40] that are used in the nutrition of poultry. Carotenoids positively affect health of both, people and animals [22, 37, 38, 41]. This aspect of observed maize inbred lines and hybrids will get priority within the healthy diet of people and animals.
Thus, according to the presented numerous and diverse results on studies of elite inbred lines (ZPPL 146 and ZPPL 159) and high-quality maize hybrids developed from these inbreds (ZP 633, ZP 735 and ZP 737), it can be concluded that ZPPL 146 and ZPPL 159 are rich in carotenoids, yellow pigments, also have significant amounts of other relevant biogenic compounds. Observed inbred lines have erect top leaves and are classified into a group of maize inbreds with significant properties of photosynthetic model and are tolerant to high temperatures. Spectral bands pointing to conformational characteristics of molecules of carotenoids but also other compounds (phosphates, glutens and amides III) were established by the resonance Raman spectroscopy method applied to the leaf of maize inbred lines. Relevant traits, properties and parameters of observed maize inbred lines indicate that the prospects of their use in breeding both for food and forage grain and green biomass for ensilaging. These maize elite inbred lines were used to develop high-quality maize hybrids (ZP 633, ZP 735, ZP 737) that are recognisable for their quality in human nutrition (children and the elderly), which is confirmed by medical observations related to their use in food, feed and industrial processing. Relevant agronomic and morphological traits of maize hybrids are presented. Moreover, results on grain structure and yields of Serbian lines and hybrids obtained in the regions of south-eastern Europe are also displayed.
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