PHENOTYPIC RESPONSE OF SPRING WHEAT PERSPECTIVE LINE GENOTYPES TO DIFFERENT ENVIRONMENTAL CONDITIONS

. Spring wheat can be a viable alternative for satisfying the agri-food market. A performant genotype is characterized by high adaptability to different environmental conditions, high grain yield capacity, and yield stability. Three new spring wheat genotypes created at Agricultural Research and Development Station from Turda were tested in six different field conditions at the State Institute for Testing and Registration of Varieties Centres for plant physiological attributes, yield


INTRODUCTION
Wheat (Triticum aestivum L.) is one of the world staple foods that is often exposed to different biotic and abiotic stress factors which cause yield reduction. Wheat grain yield and quality are complex traits which involve many minor genes, the phenotyping expression of these two main agronomic characters involve interaction between a series of biochemical processes and a great number of genes (Stone and Savin, 2000). These traits are defined through the combination of genetic and environmental factors such as soil characteristics, precipitation, fertilization, soil and air temperature, as well as the genotype × environment interaction (Peterson et al., 1992;Johansson et al., 2003).
Spring wheat represent a real and viable alternative to meet food needs. Generally, the yield of wheat has doubled over the last 30 years due to a combination of advanced agronomic practices and improved germplasm through selective breeding (Lopez et al., 2014). In the last years, spring wheat areas have more than doubled in some part of European areas (Jalli et al., 2021) as a result of climate changes and high adaptability of this wheat ideotype (Sapega and Tursumbekova, 2018).
The duration and structure of the plant vegetation period are among the most important biological characteristics that determine economic value of cereal crop varieties and their suitability for cultivation in a specific climatic zone (Likhenko et al., 2015). Assessing adaptation to different environmental conditions as the combination of performance and responsiveness offers breeders opportunities to select for grain yield stability across a range of environments, as well as genotypes with higher relative yield in stress conditions (Telfer et al., 2022).
Worldwide, the annual increase in the grain yield of spring wheat achieved through genetic means ranges from 0.5% to 1.5% (Aisawi et al., 2015;Xiao et al., 2012). Genetic gain in yield potential was achieved neither by reducing plant height or by incorporating Rht genes, but 40% was associated with greater 1000-kernel weight, 20% to more grains per unit area, and by greater resistance to leaf rust (Morgounov et al., 2010). Some studies also showed that the genetic contribution to grain yield of non-yield-related traits closely associated with yield was significantly higher than that of the yield components (Feng et al., 2021). In crop breeding, the timing of anthesis is important for the adaptation of crops to a particular environment and therefore determines crop yield under field conditions (Perry and D'Antuono, 1989;Richards, 1996).
Grain yield potential can be appreciated through analysing the main yield components. Thousand kernel weight (TKW) is one of the main yield components. However, with increasing occurrences of post-flowering abiotic stress associated with climate change, TKW may become severely limiting and hence a target for breeding. The TKW and its development from anthesis to maturity, becomes of high interest when studying post-anthesis abiotic stress, since any genetic variability associated with this trait could represent an interesting source of tolerance to extreme climatic events whose occurrence will likely increase in the future (Beral et al., 2020).
Hectoliter weight (HW) often referred to as specific weight or test weight, can be associated as a physical quality parameter commonly used in the cereals as an indirect indicator by the milling industry (Murphy et al., 2007;Okuyama et al., 2020). Along with the genetic determinism regarding the grain size, any indirect factors as weathering, nutrient deficiency, high temperature during grain filling process, production systems, plant lodging, shriveled or imature grains, can reduce the test weight (Dunăreanu and Bonea, 2022;Donelson et al., 2002;Isleib, 2012). According to Ilker et al. (2009), a safety-first selection index may be effective in selecting superior wheat genotypes especially for test weight, which is one of the physical quality parameters important in determining flour yield in wheat. The hectoliter weight has also been positively correlated with grain yield (Iqbal et al., 2016) but greatly influenced by the environment (Joshi et al., 2018).
This study presents a framework for the assessment of the genetic basis of adaptation to different environment conditions with improved relevance to breeders' selection objectives. Aims: four spring wheat genotypes was tested under different environment condition for its grain yield capacity and grain quality to identify the specific spring wheat ideotype to Transylvanian Plain conditions.

MATERIALS AND METHODS
Three spring wheat perspective lines created at Agricultural Research and Development Station from Turda alongside by the old spring wheat variety Pădureni were sown in six different environment conditions to establish their adaptative capacity and productive potential. The biologic material was teste in field condition in six testing centres of the State Institute for Testing and Registration of Varieties (ISTIS) during 2022. The six testing centres include a wide range of pedo-climatic conditions specific to the Transylvanian Plateau.
The specific climatic conditions of these six testing centres are presented in the figure 1 (a, b). Regarding the rainfall conditions, for most testing centres the rainfall level before seeding was poor, especially at Târgu Secuiesc where both in February and March cumulative precipitation level was 3.2 respectively 5.1 mm. A low precipitation level was maintained for April at the same testing centre (25.06 mm), while for May and June the precipitation was optimal. A good level of rainfall was registered before and after sowing date at Sibiu and Hărman centres (February, March and April) which ensured the spring wheat plants a normal and uniform emergence. Unfavourable rainfall conditions were registered at Harman Centre for May, June and July, which has a negative influence on plants growth and development stages. Even if in the Simleu Silvaniei the sum of rainfall was superior to other testing centres, the low level of rainfalls during the plants development stages (May) they showed a negative influence on plants agronomic traits influencing their performance. The temperature regime in the six test centres shows a normal increase of these during the spring and summer months, with a very high temperature registered in Simleu Silvaniei centre especially for February and March (6.5, respectively 8.4⁰C). The same superiority of temperatures was maintained also for the rest of the vegetation period, the highest mean temperature being registered in June (25.3⁰C) with more than 5⁰C as against other test locations.

RESULTS AND DISCUSSIONS
Regarding vegetation period of the studied genotypes (figure 2) can be observed that is no significant differences between number of days from emergence to ripening stages. A small difference can be observed between studied genotypes from plant emergence to booting stage, T. 4076-19 genotype being earlier than the  Thousand kernel weight is a complex agronomic trait with a complex genetic determinism based on which can be partially appreciate the grain yield potential. It is known that climatic condition can have a great influence on this trait such as the unfavourable conditions from grain filling period can have a negative effect. Even if the TKW has a high genetic determinism, the climatic conditions, especially the rainfall regime during the testing year has determine a large variability for Pădureni variety, this trait ranged between 30.0 g in Simleul Silvaniei conditions to 42 g in Harman local conditions (figure 3). The highest TKW mean value was registered for T. 4162-19 genotype (36.7 g) which has also a large variability in the six testing centres between 32.0 g at Simleul Silvaniei to 45.0 g in Harman. The smallest TKW mean value (32.8 g) was observed for T. 4107-19, whose values they have varied from 26.0 g to 42.0 g in Sibiu testing centre, respectively at Harman. The TKW values for T. 4076-19 genotype range between 27.0 g in Sibiu conditions to 43.0 g at Harman with close average value to that of the Pădureni vatriety. Regarding the HW values for studied genotypes, a superior mean values were registered by T. 4162-19 genotype (77.0 kg hl -1 ) with an amplitude of this trait by 15 units between Târgu Secuiesc and Hărman centers. A close mean HW values can be observed for Pădureni and T. 4076-19 genotypes (75.7, respectively 75.8 kg hl -1 ) for the six testing centers, even if there were differences between the two genotypes from one center to another. T. 4107-19 genotype has recorded an inferior mean value for HW compared to the other studied genotypes having, however, higher values than the other genotypes under the conditions from Simleul Silvaniei.   The grain yield performance as a complex trait resulting from the interaction between genotype and environment conditions are presented in figure 5. The complexity of this quantitative trait has determined a large variability between genotypes and specific pedo-climatic conditions. In case of Pădureni genotype, the average yield registered for the six different ecological conditions was by 4.00 t ha -1 , with a minimum grain yield observed in Simleul Silvaniei center (2.43 t ha -1 ) and the highest at Sibiu (5.31 t ha -1 ).

Figure 5. The grain yields of studied genotypes in different pedo-climatic conditions
A good level of grain yield can be also identified for T. 4076-19 genotype (4.85 t ha -1 ) with the minimum grain yield registered in Simleul Silvaniei (3.11 t ha -1 ) and maximum in Dej conditions (6.92 t ha -1 ). Regarding the behavior of T. 4162-19 genotype, this has exceeded 5 t ha -1 proving a high yielding capacity. As in case of the other studied genotypes, the unfavorable climatic conditions from Simleul Silvaniei have determine the lowest production of the six test centers (3.07 t ha -1 ) and the highest (7.90 t ha -1 ) being registered in Dej conditions. Of the four tested genotypes, T. 4017-19 proved to be the most productive of these obtaining an average grain yield with 1.35 t ha -1 more than the control (Pădureni). The superior capacity of production of this genotype was demonstrated in each testing center especially in Sibiu and Radauti centers where the mean grain yield of this perspective line has exceeded with 0.5, respectively 0.6 t ha -1 the next genotypes. Also, compared to the control genotype-Pădureni, the perspective line T. 4107-19 recorded superior yields between 0.35 t ha -1 at Targu Secuiesc center to 2.8 t ha -1 in Dej center conditions. Spring wheat plants have an accelerated process for growth and development so that the lack or low levels of rainfalls can have a significant influence on yield or quality traits. Thus, in our study the rainfalls from stem

ISTIS Centres
The lack of significant correlation between thousand kernel weight and rainfalls strengthens the assumption that the TKW trait is more dependent on the genotype than other external factors. A significant positive influence on this trait can be observed in case of T. 4162-19 genotype when the rains occurred in the first decade of June determine an increasing TKW. A negative relationship between hectoliter weight (HW) and rainfalls from second decade of June for all genotypes what suggest that grains quality can be affected by a short period of drought associated with a low temperature. Also, a positive relationship between rainfalls from end of April and HW can be observed in case of T. 4076-19, respectively T. 4162-19 genotypes.

CONCLUSION
All three spring wheat genotypes was identified as high productive cultivars with a good adaptability to different environment conditions. Compared to the control genotype-Pădureni-the three new genotypes are productively superior with 21 to 33%. The quality indices for studied spring wheat genotypes valued on the basis of HW are close to the control genotype which means that improvement of grain yield was achieved without sacrificing its quality.