Agronomic characterization
Mean values of various agronomic and nutritional data recorded during the present study have shown significant differences among various accessions. Significant variability was observed for various quantitative traits within the accessions studied (Table 1).
Plant height varied from 34.8 cm (IC-0622345) to 64.6 cm (IC0615770), floret number per flower head from 30.2 (IC-0622340) to 74.3 (IC-0622358), 100 seed weight from 0.132 (IC-0622345) to 0.178 mg (IC-0622358), dry matter per plant from 18.0 g (IC-0622345) to 49.4 g (IC-0622358), leaf length from 22.82 mm (IC-0622340) - 65.42 mm (IC-0622358), leaf width varied from 13.7 mm (IC-0622340) to 45.5 mm (IC-0622358). A high coefficient of variation was observed in leaf width (33.35), dry matter (26), leaf length (19.89), floret number per flower head (19.92), plant height (16.64) and less coefficient of variation was observed in forage quality parameters. Crude protein (%) showed a range of (20.21-23.64%), NDF (48.35-54.23) and ADF (37.17-42.78). Significant variation was also observed in ‘V’ marking, in some accessions, conspicuous in some whereas less prominent in others as well as absent in some (Plate 1).
Probably, the present study would be the first of its kind analysing the morphological variability of red clover in India. However, its genetic diversity has been reported by few researchers around the world (De
vega et al., 2015; Jones et al., 1997). Although, a similar study was carried out with comprehensive characterization as well as comparative evaluation of white clover germplasm based on a number of agromorphological traits in mid-hills of Himachal Pradesh, India
(Singh et al., 2021). Climate variables play a pivotal role in determining the genetic structure of plant populations
(Greene et al., 2004). Dendrogram based on the average linking methods grouped 26 accessions into three clusters (Fig 1). Cluster I consist of two accessions (IC-622345 and IC 622340), cluster- II consists of 04 accessions (IC- 622377, IC-622381, IC-622373 and IC-615770), cluster-III can be grouped into sub-cluster –IIIA with 06 accessions ( IC-622408, IC-622378, IC-615793, IC-622384, IC-622354 and IC-622394), cluster- III B with 14 accessions comprises of IC-622375, IC-622374, IC-622400, IC-615794, IC-622358, IC-622417, IC-622364, IC-622335, IC-622402, IC-615787, IC-622423, IC-615772, IC-615792 and IC-615781. The results are in conformity with the studies conducted in other legume crops by
Goudar et al., (2017) and
Wankhade et al., (2017) and
Makwana et al., (2024).
MaxEnt analysis
We have used MaxEnt for generating Ecological Niche Models based on current and future climatic grids. Maximum entropy (Maxent) as a niche modelling approach has been used for making predictions or inferences from incomplete information. The species distribution models generated for red clover based on current and future climate grids have been presented (Fig 2 and 3) respectively. The probability distribution has been calculated as the sum of each weighted variable divided by a scaling constant to ensure that the probability value ranges from 0 to 1. The program starts with a uniform probability distribution and works in cycles adjusting the probabilities to maximum entropy. It iteratively alters one weight at a time to maximize the likelihood of reaching the optimum probability distribution. The information available about the target distribution of red clover often presents itself as a set of real-valued variables, called ‘features’ and the constraints are that the expected value of each feature should match its empirical average
(Phillips et al., 2006).
The potential regions identified for red clover genetic resource management in Kashmir valley, Himachal Pradesh and Uttarakhand have been provided (Table 2).
A total of 21 districts were identified in three states/UTsof India covering 11 districts inthe UT of J and K, 06 in Himachal Pradesh and 04 in Uttarakhand, respectively, for cultivation and
on-farm conservation of red clover. Table 3 gives an estimation of relative contributions of the environmental variables to the MaxEnt models of current and future climatic conditions. Bioclimatic variables
viz., temperature annual range (bio 7), precipitation of coldest quarter (bio 19), precipitation of driest month (bio14), minimum temperature of the coldest month (bio6), precipitation of wettest quarter (bio 16) contributed maximum to the current climate model with percentage values of 46.6, 9.9, 9.3, 5.1, 5.1 respectively (Table 2). Interestingly, the niche model for future climate governed by the bioclimatic variables, Mean temperature of warmest quarter (bio 10), temperature annual range (bio 7), precipitation of wettest month (bio 13), precipitation of driest month (bio 14), precipitation of coldest quarter (bio 19) with percentage values of 33.2, 18.5, 14.2, 8.9 and 12.6 respectively.
MaxEnt is considered as the most accurate model performing extremely well in predicting occurrences with other common approaches (
Hijmans and Graham, 2006), especially with incomplete information. Such modelling of red clover geographic distributions based on locality factors provides an important information on the ecology, conservation biology and invasive-species management (
Welk et al., 2002;
Peterson and Shaw, 2003). The MaxEnt modelling approach can be used in its present form for many applications with presence-only datasets and merits further research and development
(Sivaraj et al., 2016). MaxEnt as a successful prediction distribution has been used by many researchers earlier, coral reefs
(Tittensor et al., 2009); forests (
Carnaval and Moritz, 2008), rare plants
(Williams et al., 2009) and many other species
(Elith et al., 2006). The availability of detailed environmental databases, comprising ofcheap and efficient computer technology, has driven a rapid increase in predictive modelling of species environmental requirements and geographic distributions. The potential impact of climate changes on terrestrial production (especially agricultural crop) varies spatially and depends on crop-specific biophysical constraints
(Kumar et al., 2021). Due to increase in animal population worldwide, the demand for fodder sources would increase in the changed climate regime. As the extensive adaptation of red clover would prove vital in meeting food security, use of MaxEnt method is highly warranted in preserving the important forage species. The potential regions identified using MaxEnt analysis would be providing new insights in red clover genetic resources in Kashmir valley and in the states of Himachal Pradesh and Uttarakhand.
DIVA-GIS diversity-analysis
DIVA-GIS diversity analysis was performed for the selected plant traits
viz., plant height, floret, dry matter, crude protein, neutral detergent fiber and acid detergent fiber (Fig 4). Diversity rich pockets exist in Anantnag, Kupwara, Badgam districts of J and K as derived from the DIVA-analysis diversity maps. High diversity values ranging from 2.1-3.0 were recorded for the phenotypic traits of red clover germplasm collected from J and K. A better perception of the red clover genetic diversity distribution is essential for its conservation and use. Hence, diversity-rich pockets are to be identified for covering maximum diversity that will help us in determining the conservation strategy and will improve our understanding of the taxonomy and the origin and evolution. The study showed a greater diversity in South-Western parts of J and K, indicating that this region is an important habitat for planning on-farm conservation. GIS mapping has been successfully used in assessing biodiversity and in identifying areas of high diversity in several crops, like
Phaseolus bean
(Jones et al., 1997), wild potatoes (
Hijmans and David, 2001), horsegram
(Sunil et al., 2008), linseed
(Sivaraj et al., 2009), blackgram (
Babu Abraham et al., 2010), medicinal plants
(Varaprasad et al., 2007) and agrobiodiversity
(Varaprasad et al., 2008).