Susheel Kumar

Socio-economic importance, domestication trends and in situ conservation of wild Citrus species of Northeast India

Northeast India is rich in Citrus genetic diversity representing several wild and cultivated species. Besides commercially cultivated species, several wild, semi-wild and domesticated species namely Citrusindica, C.macroptera, C.ichangensis, C.latipes, C.megaloxycarpa and C.assamensis are found to grow in Northeast India. These species have great potential in improvement of Indian Citrus industry being source of genes for combating biotic and abiotic stresses. The natural diversity of these genetic resources is shrinking at alarming rate due to large scale deforestation, shifting cultivation practiced in these areas and climate change scenario in this important hotspot of biodiversity. Socio-economic importance of each species have been studied during surveys and interesting domestication trends were observed based on their cultural and economic significance, which led to “in situ on farm” conservation of C.indica, C.macroptera and threat to C.megaloxycarpa and C.ichangensis. Consequently, genetic resources of most of these species are facing severe threat of extinction necessitating policy interventions and adoption of dynamic conservation and management strategies. Species specific conservation strategy especially through “in situ on farm” conservation has been proposed with suitable sites in Northeastern Indian states based on population structure and suitability of habitat. Farmers’ support through “The Biological Diversity Act, 2002” and “The Protection of Plant Varieties and Farmers’ Rights Act, 2001” of India would bring the required impact on management of these complex genetic resources of Citrus. In the present study, we have documented the current status, socio-economic potential, domestication trends and associated traditional knowledge of these wild and semi-wild Citrus species occurring in Northeast India and enumerated suitable conservation strategies and desired policy interventions for their dynamic conservation and sustainable utilization.

Socio-economic and horticultural potential of Khirni [Manilkara hexandra (Roxb.) Dubard]: a promising underutilized fruit species of India

Manilkara hexandra (Roxb.) Dubard (Khirni) is a socio-economically important fruit and nut species of tribal population of tropical deciduous forests of western and central India. Survey and collection missions were undertaken to study the extent of variability and socio-economic importance of Khirni germplasm in diversity rich areas of Rajasthan, Gujarat, Madhya Pradesh and Maharashtra. A total of 99 accessions of this important tree species were collected from surveyed regions, of which 47 diverse accessions were selected for morphological characterization showing wide range of variation in agro-morphological traits. During the survey, sizable variability in morphological characters and high socio-economic potential of Khirni was recorded. Bark, fresh fruits and extracted seeds have high nutritional and medicinal value. Tree provides substantial livelihood support to local inhabitants as collected fresh fruits from natural populations fetch good price in local markets. Besides livelihood support species, M. hexandra contributes in the nutritional security of the women and children of this area by fulfilling the need of micronutrients and vitamin A. Due to the high market demand of fresh fruits and seeds and without any organized cultivation, pressure on natural wild populations is severely building up since last several decades and therefore, the genetic variability of this species is now facing a great threat and need immediate complementary conservation efforts. Based on higher diversity index and natural population size of this species six in situ conservation sites have been suggested for dynamic conservation in western and central Indian states and 60 accessions have been successfully cryostored.

Inferring Phylogenetic Relationships of Indian Citron (Citrus medica L.) based on rbcL and matK Sequences of Chloroplast DNA

Phylogenetic relationships of Indian Citron (Citrus medica L.) with other important Citrus species have been inferred through sequence analyses of rbcL and matK gene region of chloroplast DNA. The study was based on 23 accessions of Citrus genotypes representing 15 taxa of Indian Citrus, collected from wild, semi-wild, and domesticated stocks. The phylogeny was inferred using the maximum parsimony (MP) and neighbor-joining (NJ) methods. Both MP and NJ trees separated all the 23 accessions of Citrus into five distinct clusters. The chloroplast DNA (cpDNA) analysis based on rbcL and matK sequence data carried out in Indian taxa of Citrus was useful in differentiating all the true species and species/varieties of probable hybrid origin in distinct clusters or groups. Sequence analysis based on rbcL and matK gene provided unambiguous identification and disposition of true species like C. maxima, C. medica, C. reticulata, and related hybrids/cultivars. The separation of C. maxima, C. medica, and C. reticulata in distinct clusters or sub-clusters supports their distinctiveness as the basic species of edible Citrus. However, the cpDNA sequence analysis of rbcL and matK gene could not find any clear cut differentiation between subgenera Citrus and Papeda as proposed in Swingle’s system of classification.

Genetic resources of Chironji (Buchanania lanzan Spreng.): a socio-economically important tree species of central Indian tribal population

Buchanania lanzan Spreng. (Chironji) is a socio-economically important underutilized fruit and life support species of tribal populations of north, west and central India. A survey and germplasm collection programme undertaken in the Indian states of Rajasthan, Gujarat and Madhya Pradesh observed that B. lanzan is found as natural wild in the forest, marginal lands and occasionally in farmer’s fields. A total of 72 diverse accessions of this important tree species were collected from the diversity–rich areas of India having wide range of variation in agro-morphological traits among the accessions. This species has high socio-economic value providing livelihood to tribal population of these areas and has high potential as commercial horticulture species. Fresh ripen fruits and extracted seed kernels have several nutritional and medicinal properties. Seed kernel and extracted kernel oil is used for the preparation of several Indian dishes. Traditional indigenous knowledge revealed immense importance of almost all parts of plant like roots, leaves, fruits, seeds and gum for various medicinal applications like cure for blood disorder, fever, ulcers, burning sensation of body, diarrhoea, dysentery, asthma, snakebite, etc. Due to direct harvesting of economically important parts of tree from natural habitat, genetic resources of B. lanzan are facing severe threat of extinction and need immediate conservation efforts.