Analysis of variance revealed mean sum of squares due to genotype to be highly significant for all traits during both years (Tables 3a and 3b). The pooled ANOVA for genotype and year were found significant (p<0.01) for all the traits while interactions were found significant (p<0.01) for only 1000 grain weight (g) and at p<0.05 for grain yield per plant (Table 3c).Tables 4 summarize the results on environmental variations for yield and yield contributing traits and micronutrient content (Zn & Fe) in fifty two wheat genotypes grown under Jammu agro-climatic conditions. Significant genetic variation among genotypes is a prerequisite to increase the concentration of Zn and Fe content in wheat grain through conventional breeding.
Significant differences between treatments at the genotypic level may result from genetic variation of genotypes, whereas significant variations at the annual level and genotype x year interactions may result from changes in humidity, precipitation, climate, soil conditions, or other cultivation practises used throughout the cropping season (Joshi et al. 2010). The environment has a big impact on yield and the qualities that make up that yield. Table 4 summarises the mean data of the morpho-metric characteristics and micronutrients (Zn & Fe) content of 52 accessions for the two following years, 2019-2020 and 2020-2021.
It was prominently elucidated the significant variation among the genotype, year, and genotype x year interactions studied. The most stable plant height was recorded in the genotype RSP-561 (100 cm in 2019-20 and 99.67 cm in 2020-21) followed by HP-02 (93.33 cm in 2019-20 and 92.67 cm in 2020-21), HP-29 (87.00 cm in 2019-20 and 86.33 cm in 2020-21) and HP-39 (86.33 cm in 2019-20 and 87.00 cm in 2020-21) whereas the highest plant height was recorded for JAUW-683 (105 cm in 2020-21). For number of tillers per plant, the most superior and stable performance was attained by the genotype HP-02 (9.33 in 2019-2020 and 10.00 in 2020-21) and HP-48 (8.00 in 2019-2020 and 9.33 in 2020-21). Plant height and number of tillers per plant are the most sensitive to environmental fluctuations. It is indicated that the relative inconsistent performance of other genotypes was marked due to genotype and environment interaction. For days to 50 per cent of flowering, the genotype HP-04 (94.33 in 2019-2020 and 95.67 in 2020-21) and HD 3086 (94.00 in 2019-2020 and 96.00 in 2020-21) projected the lowest days to 50per cent of flowering which could be directly correlated with early maturity. While the sable genotype was achieved by HP-03 (95.67) and HP-08 (97.33). Plant heights, flag leaf, days to 50 per cent of flowering and seed morphological variation are the primary descriptor for characterization of germplasm. The leaf morphological traits of the wheat germplasm (9HPYT) under study showed a wide range of variability. Regarding the flag leaf, it was found that RSP-561 (30.23 cm) showed the most consistent trait during the two years investigated, followed by HP-22 (26.23 cm for 2019–20 and 26.57 cm for 2020–21), HP–09 (27.70 cm for 2019–20 and 28.23 cm for 2020–21), and HD 3086. (27.73 cm for 2019-20 and 28.37 cm for 2020-21). While in reference to spikelets per spike, the stable performance was presented by HP-39 (18.67) followed by HP-15 (18.00) and HP-03 (16.33) while in case of days to maturity, genotype HP-14 (137.67) and lowest days to maturity was recorded in genotype, HP-04 (133.67 in 2019-20) and RSP-561 (133.67 in 2020-21). 1000 grain weight (g) and grain yield per plant (g) are the major economic traits and are important for successful agronomic practices and global demand. Thus, exploiting the highest 1000 grain weight (g) was observed for both the years in genotype HP-47 (46.40g in 2019-20 and 43.63g in 2020-21) followed by HP-21 (43.67 in 2019-20g and 8.87g in 2019-20), whereas for grain yield per plant (g), genotype HP-09 (24.40 g in 2020-21) followed by HP-02 (24.33g in 2020-21) and HP-40 (23.30g in 2020-21) was recorded highest. While the most stable genotype for 1000 grain weight (g) was recorded in HP-06 (37.40) followed by HP-19 (42.33 gm in 2019-20 and 42.50 gm in 2020-21), HP-13 (39.00 gm in 2019-20 and 38.83 gm in 2020-21), and grain yield per plant (g), was revealed by genotype HP-08 (14.13) followed by HP-26 (14.37 gm), HP-27 (10.47 gm) and HP-28 (16.03) in 2019-20 and 2020-21, respectively. Highly significant differences among the genotype were observed for both grain Fe and Zn concentration indicating the presence of sufficient amount of genetic variability for grain Fe and Zn concentration among the genotypes studied. The pooled mean percentage of Zn and Fe in grain of the fifty-two accessions ranged from 8.00 ppm to 40.67 ppm and 27.33 ppm to 41.67 ppm in Zn and from 9.67 ppm to 88.33 ppm and 28.67 ppm to 72.33 in Fe for 2019-20 and 2020-21, respectively (Fig. 2). The accession HP-45 (41.67 ppm in 2020-21) was recorded to establish the highest Zn content followed by accession HP-41 (40.67 ppm in 2019-20) and HP-02 (40.33 ppm in 2020-21), while the highest Fe content was depicted by HP-49 (88.33ppm in 2019-20 and 72.33 ppm 2020-21) Followed by HP-44 (71 ppm in 2019-20 68.67ppm in 2019-20) and HP-45 (55.00 ppm in 2019-20 and 51.67 in 2020-21). Since grain contains higher amounts of Zn and Fe, it is possible that harvesting plant will assist in the sustainable exploitation of natural conservation. As a result of polygenic control, environmental or nongenetic factors, and their interaction, few accessions, on the other hand, showed inconsistent Zn and Fe content over the course of two years (G x E interaction). When the performance of the traits was compared between the two years, it was evident that the accessions performed better in the first year for many morpho-metric and yield-attributing variables, including plant height, days to 50% of flowering, flag leaf, spikelets per plants, and Zinc (ppm) (2019-20). The accessions performed superior for number of tillers per plant, 1000 grain weight (g), and grain yield per plant (g) and iron (ppm) characters in the second consecutive year (2020-21), Overall based on the ten morpho-matric attributes, Zn and Fe content, the accessions HP-08, HP-26, HP-27, HP-28, HP-33, HP-41, and HP-49 displayed a comparable consistent performances pattern in the agro-climatic conditions of the North Western Himalayan region for the two consecutive years studied. HP-33, HP-41, HP-45 and HP-49 had higher Zn and Fe content.
Regarding qualities that contribute to yield, other genotypes behaved differently in both years. The findings showed that genotype-by-environment interactions complicate crop variety development and decrease the efficacy of breeding programmes aimed at improving yield (Ahmad et al. 2011). When the experimental materials for the current study were evaluated during the two years (2019–20 and 2020–21), different patterns of minimum and maximum temperature and rainfall were observed (Fig. 1). This gave researchers the chance to examine how genetic make-up and/or environmental factors affect the level of Fe and Zn (Kumar et al. 2018). The development of breeding techniques for creating biofortified wheat cultivars is aided by knowledge of the interplay between genotype and environment. Given that genotype x year interactions were significant in the current study for both Fe and Zn content, it is likely that a sizeable amount of the Fe and Zn content in wheat seed depends on soil conditions, crop management techniques, temperature, precipitation, and these factors (moisture, aeration, and soil pH). In contrast, substantial genotype x location interactions for Zn and Fe concentrations in both wild and cultivated cultivars of wheat were found (Ortiz-Monasterio et al. 2007; Trethowan 2007; Gomez-Becerra et al. 2010). Year-to-year changes in Fe and Zn content were likewise extremely significant in the current investigation, showing that the environmental conditions depicted in Fig. 1 were present. Fifty-two genotypes were divided into eight clusters based on the K mean cluster. The distribution pattern of genotypes in the different cluster is presented in Fig 3. The cluster VI was the largest cluster consisting of 15 genotypes followed by cluster I (10 genotypes), cluster III having 8 genotype, cluster VII having 7 genotypes, cluster IV (6 genotypes), cluster VIII (3 genotypes), cluster V (2 genotype) and cluster II having 1 genotype. It is pertinent to mention that all the zinc and iron enrich genotypes were obtained from the Harvest Plus breeding programme and likely to have some part of common ancestry and thus fall in the same cluster. Similar results have been reported by Ajmal et al. (2013); Shahryari et al. (2011). The clustering of genotypes from different ecogeographic region into one cluster could be due to exchange of breeding material among global partners. Dendrogram was achieved from cluster analysis of fifty-two genotypes on the basis of two micronutrient (Zn & Fe) content (Fig 4). According to this grouping under- study wheat genotypes divided to seven clusters. Cluster II and VI will can consider most desirable cluster for selecting the genotype for use in hybridization.
It is possible to simultaneously increase the concentration of zinc and iron in grains by selection because the genotypic and phenotypic correlations between zinc and iron were highly positive (Table 5). By Velu et al. (2012) and Chatrath et al. (2018), similar associations between grain iron and zinc concentration were reported. The genotypic connection between the iron and days to maturity was highly positive, and Velu et al. (2012) observed a similar finding. Similar results were found by Velu et al. (2012) and the zinc yield had a significantly favourable phenotypic connection with days to maturity. Spikelets per spike and grain weight revealed a substantial positive genotypic connection with grain yield (Table 5). According to Joshi et al. (2007) the number of effective tiller and grains per spike are the most important traits for grain yield in wheat. From this research, genotypic correlation between grain yield with days to 50 percent flowering and flag leaf area was found significant negative (-0.158**) and (-0.170*) respectively.