In India, fennel productivity remains low owing to the dearth of high-yielding and stable varieties. A survey of the literature indicates limited genetic improvement research has been conducted on fennel. There is a lack of adequate genetic variability, limited information on the genetics of economically important traits, inadequate knowledge of population dynamics anda high degree of genotype-environment interaction.
Analysis of variance
A comprehensive analysis of variances for all characters under investigation has been compiled in the tables. The scientific findings in Table 1 stipulated a highly significant difference encompassing through the ten characters examined, in conjugation with days to flower initiation, days to 50% flowering, plant height, number of branches per plant, number of umbels per plant, number of umbellets per umbel, number of seeds per umbel, test weight, seed yield per plant andseed yield (kg/ha). This demonstrates considerable genetic variation among the genotypes.
Range and mean performance
Variability denotes the existence of differences among individuals within a plant population. Such variability is essential for the success of any crop improvement initiative. Mean performance has been depicted in a tabular form in Table 1. The initiation of flowering across varied genotypes exhibited a range from 71.33 days for JF-3 to 91 days for RF-67. The genotypes JF-1 and JF-2 demonstrated the earliest flowering initiation, occurring at 71.33 days and 72.67 days, respectively, indicating a shorter duration prior to flowering. The plants demonstrated a variation in height spanning from 116.40 cm to an impressive 195.67 cm, specifically in the RF 281 and HF-192 genotypes. Genotype NDF-46 measuring 190.54 cm was commensurable to the grand mean height of 157.72 cm.
The fennel genotypes demonstrated an average of 11.86 umbels per plant, illustrating a diverse range of variance from 4.46 in Jagudan-2 to 24.00 in RF-125. Maximum umbel production was achieved by RF-125, closely followed by RF-143 with 21.06 and RF-281 at 21.00. In terms of seed yield per plant, figures span from 15.27 g in RF-205 (Check) to 33.13 g in RF-143, yielding a mean of 23.84 g.
Coefficients of variation
Coefficients of variation referred to phenotypic and genotypic traits, accompanied with heritability and genetic advance as a percentage of the mean, are detailed in Table 2. The table illustrates significant variability among genotypes for each measured characteristic. Genotypic coefficient of variation (GCV) exhibited a range from 6.088% to 47.799%, particularly for the trait of days to 50% flowering and the number of umbels per plant, respectively. Phenotypic coefficient of variation (PCV) expressed the values of range 6.51% to 49.14%, corresponding to the traits of days to 50% flowering and the number of umbels per plant, respectively. The phenotypic coefficient of variation was generally greater than the genotypic coefficient across all traits suggesting that environmental factors significantly influence trait expression. Comparable results were observed by
Meena et al. (2010) and
Meena et al. (2017).
Heritability and genetic advance
Heritability range was determined in accordance to the criteria given by
Johnson et al. (1955). Traits displaying high heritability were recognized as those with values exceeding 80%, whereas those with moderate heritability fall in between the range of 50% to 80% and the traits with low heritability were characterized by values below 50%. Estimates of the anticipated genetic improvement for various traits were calculated using a selection intensity of 5%.
Correlation coefficient
Correlation coefficient determines the impact of one variable on another which has been depicted in Table 3 and 4. Plant height demonstrated a significant positive correlation with seed yield per plant (0.899), followed by the number of seeds per umbel (0.606) and the number of umbelletes per umbel (0.578). Number of primary branches depicted a strong positive correlation with the number of umbels per plant (0.901). Umbel number per plant showed a highly significant positive correlation with seed yield per plant (0.410). The number of umbelletes per umbel also had a highly significant positive correlation with both the number of seeds per umbel (0.658) and test weight (0.456). However, the number of seeds per umbel displayed a significant negative correlation with seed yield (-0.453) and a non-significant positive correlation with seed yield per plant (0.101). In the current study, seed yield per plant demonstrated a significant positive correlation with the number of umbels per plant and the number of seeds per umbel. Additionally, it showed a positive yet non-significant correlation with the number of effective branches per plant, the number of umbellets per umbel andtest weight. These results suggests that these traits are pivotal in determining yield in fennel. The positive correlation of seed yield per plant aligns harmoniously with previous findings by
Yadav et al. (2013),
Kumar et al. (2017),
Pawar et al.,(2018) and
Shekhawat et al., (2022).
Path coefficient analysis
Path coefficient analysis evaluates the connectivity of several yield relevant attributes. The number of days until flowering initiation demonstrated a negative direct impact on seed yield, quantified at -0.4586. Moreover, it showed a positive indirect effect for various factors, such as seed yield per hectare (0.0201), plant height (0.0149) andtest weight (0.186). Nonetheless, it showed a negative indirect effects
via days to 50% flowering (-0.4376), the number of primary branches (-0.086), the number of umbels per plant (-0.0948) andthe number of umbellets per umbel (0.0636). A direct effect of days to 50% flowering on seed yield was positive, recorded at 0.1586 and indirect positive influences were observed through the number of umbellets per umbel (0.0201), the number of umbels per plant (0.0017), seed yield in kg/ha (0.0285), the number of primary branches (0.0167) andplant height (0.0167). However, it also exhibited a negative indirect effect through seeds per umbel (0.0133) and test weight (-0.0725). Plant height contributed positively to seed yield with a direct effect of 0.0421. Its indirect negative effects were associated with the number of umbels per plant (-0.0224), the number of primary branches (-0.0221) anddays to flowering initiation (-0.0014). On the other hand, it showed positive indirect effects on seed yield through seed yield in kg/ha (0.0098), the number of umbellets per umbel (0.0272), test weight (0.0153) andthe number of seeds per umbel (0.0258).
The correlation coefficient’s magnitude between a causal factor and its effect closely align with its direct effect. Therefore, the correlations elucidate the genuine interrelationships and indicate that direct selection of these parameters would be beneficial. These results align with the findings of
Kumawat et al. (2020),
Afshar et al. (2019) and
Sengupta et al. (2014), while
Cosge et al. (2009) and
Yaldiz and Camlica (2022). highlighted the positive and significant direct effect of test weight on seed yield in fennel.
D2 analysis
Intra and inter-cluster D2 values
These values are depicted in Table 5. Cluster V exhibited the most substantial intra-cluster distance, succeeded by cluster III (25.13), Cluster II (22.13), Cluster I (17.01) and Cluster IV (16.19). Notably, clusters VI, VII, VIII and IX recorded no intra-cluster distance. In terms of inter-cluster divergence, Cluster IX and IV displayed the greatest distance (87.78), followed closely by Cluster VIII and Cluster IV (79.73), while Cluster V recorded the least inter-cluster distance. In the current study, 24 genotypes of fennel were categorized into nine unique, non-overlapping clusters, highlighting a significant level of diversity among the genotypes. The primary clusters identified in the genetic divergence analysis predominantly included genotypes from varied origins. However, it was also noted that the genotypes from the same origin or geographic area were often clustered together. Instances of both diverse and geographically similar genotypes being grouped within the same clusters are frequently observed. Comparable results were also documented by
Choudhary et al., (2017),
Deswal et al. (2017),
Meena et al. (2010),
Jat and Chaudhary (2021),
Singh et al., (2022) and
Prajapati et al., (2022).
Cluster mean (Tocher’s method)
The cluster means for the ten characters, as determined by Tocher’s method are presented in Table 6 and Fig 1. It reveals a significant degree of variation across all characters examined. Specifically for the days to flowering initiation, Cluster I exhibited the highest mean at 87.42 days while Cluster IX recorded the lowest mean at 71.67 days. In terms of days to reach 50% flowering, Cluster IX again had the lowest mean at 83 days, whereas Cluster I had the highest mean at 98.17 days with Cluster III following at 62 days. Regarding plant height, Cluster V achieved the tallest average at 177.85 cm in contrast to Cluster IV which had the shortest average at 118.87 cm. Similar results were given by
Choudhary et al., (2017),
Deswal et al. (2017),
Meena et al. (2019),
Jat and Chaudhary (2021),
Singh et al. (2022) and
Prajapati et al. (2022).
Grouping of genotypes
The classification of twenty four genotypes of fennel revealed in a sophisticated arrangement in Table 7 into nine distinct clusters. Cluster I, II and V each showcased a remarkable collection of four genotypes, while the Cluster III comprised six genotypes. Cluster IV included two genotypes and Clusters VI, VII VIII and IX each contained a single genotype. The findings contemplate with
Tiwari et al., (2024); Yadav et al. (2013) and
Kole et al. (2023);
Singh and Singh (2022).
Raking and per cent contribution of characters
The per cent contribution presented in Table 8 of individual characters toward the total divergence was higher for number of seeds per umbel (52.54%) which was followed by seed yield (33.70%.), test weight (10.51%), seed yield per plant (2.17%), number of umbel per plant (0.72%) and plant height (0.36%). The result were in accordance to the findings of
Tiwari et al. (2024);
Yadav et al. (2013) and
Kole et al. (2023);
Singh and Singh (2022).