**Abstract**

Plants display an assorted collection of reproductive tactics that eventually play a crucial role in perpetuation of species. Plant reproductive ecology is principally concerned with the adaptive implications of the plant in their vicinity, disparity in qualities allied with pollination, seed dispersal, and seedling establishment. The success in reproduction in most flowering plants depends on ecological interactions with pollinators and seed dispersal agents. Modern tactics in reproductive ecology can integrate proper surveys, advanced pollination studies, interaction between flower and pollinators and clear assessments of population genetic structure, which can provide new opportunities for plant reproductive biology. Alfalfa is an important forage legume and known as "Queen of forages" due to its worldwide adaptability, high yield potential and quality. Alfalfa produces seeds which are primarily used for forage production. It is a gift to livestock industry including dairy, beef, horses, and sheep for grazing, silage, hay etc. Alfalfa is also a medicinal herb with antioxidant, antidiabetic, anti-inflammatory, neuroprotective and cardioprotective properties, utilized for treatment of arthritis, kidney problems. The seeds are exploited in alfalfa sprout industry. The current chapter highlights the reproductive biology of alfalfa from flower development to seed production and its advances.

**Keywords:** alfalfa, reproductive ecology, forage, seeds

### **1. Introduction**

Reproduction is the critical phase in the life time of any organism, which ensures its perpetuation as a discrete species. The accomplishment of the phenomenon is greatly influenced by two components *viz.,* intrinsic reproductive biology of the organism and the interactive niche in which they survive. The environment in which the plants grow has a major impact as it is decisive in every step of reproduction in plants, due to the fact that the plants are immobile [1]. Therefore, the reproductive success of plant can be constrained by any attributes in the ecosystem where they grow. Alfalfa (*Medicago sativa* L.), commonly called as Lucerne in many other countries is the most important forage crop accounting for the major load of hay produced globally; recognized as the back bone for many forage systems. In Gulf region, alfalfa is widely cultivated and is recognized as the first cultivated forage crop occupying around 30% of the cultivated area [2]. Alfalfa produces nutrient dense foliage with great palatability and digestibility to

the cattle. Alfalfa yields better than most forages under less ideal environmental conditions due to its deep root system. Besides, it has long been used medicinally for treatment of arthritis, kidney problems and has antioxidant, antidiabetic, anti-inflammatory, neuroprotective and cardioprotective properties. The factors that impede with the reproductive ecology of alfalfa from reproduction through pollination, seed production and dispersal and the recent advances are highlighted in the current review.

#### **1.1 Plant reproductive biology**

Reproductive awareness of any plant is vital for understanding its seed production and dispersal for the continuation of the generation [3]. Plants that do not reproduce vegetatively, depend on seeds to produce offsprings. To be established into a new generation, plants must be pollinated to form fruits, ovules must be fertilized to form viable seeds and the seeds must be dispersed to suitable substrates for germination and growth [4]. Any weak link or break in the chain of events restricts a plant's ability to reproduce and over constant time, contribute to deprivation and impedes the continuation of generation, thereby conservation [5]. Plant reproductive biology may encompass the pollination mechanisms, seed set and seed dispersal between and within populations. Consequently, a comprehensive acquaintance in reproductive knowledge of any plant is mandatory to develop strategies for its conservation [6]. Reproductive biology is a science dealing with the study of the relations between plants and pollinators as well as seed or fruit dispersers. Pollination is an indispensable event in the sexual life of flowering plants, signifying a biotic mutualism between flora and fauna [7]. It is the decisive phase for successive reproduction and suitability of flowering plants for maintenance of seed set and genetic diversity. Pollinators play a key role in reproduction of all flowering plants in the globe, especially agricultural crops depend on pollinators for successful crop production [8]. More than 87% of flowering plants are pollinated by pollinators and insects constitute the major group among pollinators. Plants and pollinators have coevolved to progress mutualistic adaptations, with large ecological changes that dissociate the coincidence in flowering and breeding cycles of pollinators. These coevolutionary relationships are now being severely affected due to global decline in pollinators caused by environmental and anthropogenic disturbances [9]. The human induced interferences such as habitat loss due to fragmentation, deforestation, irrational agricultural practices, extensive use of harmful chemical pesticides, etc. tend to unfasten the advantages of mutual adaptableness of plants and pollinators. The ecological impacts such as pollution and climate change also cause severe threat. Limited pollen or nectar production in plants or ineffective pollinator services due to environmental changes are the chief reasons for the fewness of several important medicinal plants, tree crops etc. [10]. Decline in pollination leads to reduced fruit and seed set, thereby curbing regeneration and limit fitness of plants. Fruit or seed dispersals is vital event for a plant to extend its generation to diverse localities including wild habitats. Thus, the ecoservices by pollinators and dispersal agents errand a crucial part in success of reproduction in a plant.

Observations and experimentation on assorted areas of pollination biology and seed dispersal ecology are a must to comprehend the countless intricacies dominant in plant-pollinator as well as seed dispersal systems [11]. The awareness in this area is a prerequisite for the conservation and management of plant and their associated animal species. Research in reproductive biology of plants will aid to develop new strategies to preserve the genetic potential of the plant species, which are crucial for restoration and reintroduction.

### **1.2 Plant reproductive ecology**

Plant reproductive ecology has arisen as the most adaptable and important fields of plant sciences. It contracts with the reproduction of plants to sustain their generation and the ecological strategies that aid to overcome reproductive catastrophe [12]. For reproductive success of plants owing to its tremendous diversity and ecological niches, substantial amount of disparity is anticipated in the ecological processes [13]. The data base of reproductive biology includes the facts of flowering phenology, floral biology, pollination mechanism, pollen-pistil mechanism, breeding system and natural recruitment.

Lately, the advancement in the particular subject has been stimulated by intensifying interdisciplinarity to address the chief global concerns of warranting food security and biodiversity conservation in the light of several hindrances in plant-pollinator-dispersal agent mutualisms [14]. In this view, the current review describes the reproductive biology of the chief forage plant, alfalfa, from flowering to seed dispersal to enhance the baseline data on its biology and identify deficiencies in its capacity to reproduce and the latest advances to overcome it [15]. The main focus is to synthesize and utilize the database for greater understanding and clarification of the ecological processes governing reproduction.
