Twenty-four years lucerne (Medicago sativa L.) breeder seed production in India: a retrospective study.

Lucerne (Medicago sativa L.) is the second most significant winter leguminous fodder crop after berseem in India. Breeder seed (BS) is the first stage of the seed production chain, as it is the base material for producing foundation and certified seeds. In India, lucerne BS demand has been reduced by 85.58% during the last 24 years (1998-1999 to 2021-2022), declining from 2150 kg to 310 kg. Out of 14 varieties released and notified so far, only nine varieties entered the seed chain since 1998-1999. It shows narrow varietal diversification and, hence, needs robust breeding programs towards enriching genetic variability and varietal development. The present study also highlights the disparity in BS demand and production over the years and puts forth the possible reasons behind the reduction in BS demand and production in the country. Out of the nine varieties, the BS demand of Anand-2 (53.11%) was highest, followed by Type-9 (19.44%) and RL-88 (13.60%). Varietal replacement rate (VRR) was found to be moderate, i.e., 23.67% for the varieties having <5 years old age in the last 3 years (2019-2020 to 2021-2022). It has also been estimated that BS produced (233 kg) during 2021-2022 can cover the approximate area of 6,300 ha at farmers' fields in 2024-2025 if the seed chain functions 100%, effectively. The present study provides a holistic overview of lucerne BS demand and production, challenges in BS production, and the way forward to develop more varieties and surplus BS production in the country.

Phenotype study of multifoliolate leaf formation in Trifolium alexandrinum L.

BACKGROUND: The genus Trifolium is characterized by typical trifoliolate leaves. Alterations in leaf formats from trifoliolate to multifoliolate, i.e., individual plants bearing trifoliolate, quadrifoliolate, pentafoliolate or more leaflets, were previously reported among many species of the genus. The study is an attempt to develop pure pentafoliolate plants of T. alexandrinum and to understand its genetic control. METHODS: The experimental material consisted of two populations of T. alexandrinum with multifoliolate leaf expression, i.e.,interspecific hybrid progenies of T. alexandrinum with T. apertum, and T. alexandrinum genotype Penta-1. Penetrance of the multifoliolate trait was observed among multifoliolate and trifoliolate plant progenies. In vitro culture and regeneration of plantlets from the axillary buds from different plant sources was also attempted. RESULTS: The inheritance among a large number of plant progenies together with in vitro micro-propagation results did not establish a definite pattern. The multifoliolate leaf formation was of chimeric nature, i.e., more than one leaf format appearing on individual branches. Reversal to normal trifoliolate from multifoliolate was also quite common. Penetrance and expression of multifoliolate leaf formation was higher among the plants raised from multifoliolate plants. Multifoliolate and pure pentafoliolate plants were observed in the progenies of pure trifoliolate plants and vice-versa. There was an apparent increase in the pentafoliolate leaf formation frequency over the years due to targeted selection. A few progenies of the complete pentafoliolate plants in the first year were true breeding in the second year. Frequency of plantlets with multifoliolate leaf formation was also higher in in vitro axillary bud multiplication when the explant bud was excised from the multifoliolate leaf node. CONCLUSION: Number of leaflets being a discrete variable, occurrence of multifoliolate leaves on individual branches, reversal of leaf formats on branches and developing true breeding pentafoliolates were the factors leading to a hypothesis beyond normal Mendelian inheritance. Transposable elements (TEs) involved in leaf development in combination with epigenetics were probably responsible for alterations in the expression of leaflet number. Putative TE's movement owing to chromosomal rearrangements possibly resulted in homozygous pentafoliolate trait with evolutionary significance. The hypothesis provides a new insight into understanding the genetic control of this trait in T. alexandrinum and may also be useful in other Trifolium species where such observations are reported.

Effects of shade on guinea grass genotypes Megathyrsus maximus (Poales: Poaceae)

Introduction: Light stress is an important factor limiting the biomass yield while combining forage production with crops or forestry. Guinea grass is a widely adapted perennial fodder grass. The species exhibits high degree of variation for morphology, adaptation and biomass yield. Objective: Since there is a need in identifying shade adapted forage grasses for the expanding area under agroforestry/silvipastures, the present investigation took the task of understanding how the morphologically distinct genotypes of guinea grass respond under different shaded intensities. Methods: In the present study, forty-four genotypes related with the shade response were studied in varying shading conditions (pure sunlight, 25, 50 and 75 % shade) created artificially. Results: Based on green and dry matter yields ranking, the genotype IG 01-98 performed the best followed by genotypes IG 01-92, IG 97-5, IG 97-6 and IG 01-89 in decreasing order. Particularly, IG 01-93 was identified as the best performing under 50 % shading conditions. On the other hand, most of the top ranking genotypes performed well both under open and up to 50 % of shade. Morphologically, these genotypes were taller and possessed longer and broader leaves. Under shaded conditions (over 50 %), leaf length and width showed an increasing trend compared to open conditions. Also, chlorophyll content increased with shading intensity. Conclusions: Most of the genotypes collected from the southern Indian humid tropical environment with early flowering nature were tolerant to shade. Differential genotypic response was observed for biomass yield and yield attributes under shade. The study established appreciable variability for shade tolerance among genotypes.

Introducción: El estrés leve es un factor importante que limita el rendimiento de la biomasa al tiempo que combina laproducción forrajera con los cultivos o la silvicultura. El zacate guinea es una planta de forraje perenne ampliamente adaptada. La especie presenta un alto grado de variación en su morfología, adaptación y rendimiento de biomasa. Objetivo: Como existe la necesidad de la identificación de pastos forrajeros adaptados a la sombra para el área de expansión bajo agroforestería /silvicultura, la presente investigación se realizó para entender cómo los genotipos morfológicamente distintos al zacate guinea responden a diferentes intensidades de sombra. Métodos: Se estudiaron 44 genotipos y su respuesta a los niveles de sombra: luz solar pura y 25, 50 y 75 % de sombra (creados artificialmente). Resultados: Basado en la clasificación de rendimientos demateria verde y seca, el genotipo IG 01-98 fue el mejor, seguido de los genotipos IG 01-92, IG 97-5, IG 97-6 e IG 01-89 en orden decreciente. Por su parte, el IG 01-93 fue identificado como el de mayor rendimiento bajo el 50 % de condición de sombra. La mayoría de los genotipos de primer nivel tuvieron un buen desempeño, tanto bajo sombra abierta como al 50 %. Morfológicamente, estos genotipos fueron más altos y poseían hojas más largas y más anchas. En condiciones de sombra, de más del 50 %, la longitud y ancho de la hoja mostraron una tendencia creciente en comparación con la condición abierta. El contenido de clorofila aumentó con la intensidad de la sombra. Conclusiones: La mayoría de los genotipos recolectados al sur de la India en un ambiente tropical húmedo y tienen una floración temprana, fueron tolerantes a la sombra. Se observó una respuesta genotípica diferencial para los atributos de rendimiento y rendimiento de biomasa bajo sombra. El estudio mostró la existencia de una variabilidad apreciable para la tolerancia a la sombra entre los genotipos.

Generation of interspecific hybrids of Trifolium using embryo rescue techniques.

The genus Trifolium Leguminosae (Fabaceae), commonly called clovers, includes 237-290 annual and perennial species, of which about 20 are important as cultivated and pasture crops. Taxonomic distribution supported by molecular analysis indicates that Mediterranean region is one of the main centers of distribution of the genus and also a center of domestication and breeding. Self-incompatibility is prevalent in the genus, controlled by a single, multiallelic gene expressed gametophytically in the pollen. It was suggested that hybridity did not play a major role in the evolution of the genus due to the poor crossability of the species under natural conditions. Interspecific hybridization in the genus Trifolium by conventional crossing techniques has been largely unsuccessful. Post-zygotic barriers appear to be a primary cause of the reproductive isolation, associated with endosperm disintegration and consequent abnormal differentiation and starvation of the hybrid embryo. As hybridization using conventional techniques has almost failed in Trifolium, embryo culture technique was used by breeders to obtain new combinations of interspecific hybrids. Embryo culture has been effectively used in developing interspecific hybrids in Trifolium ambiguum, T. pratense, T. montanum, T. occidentale, T. isthomocarpum, T. repens, T. nigrescens, T. uniflorum, T. sarosiense, T. alexandrinum, T. apertum, T. resupinatum, T. constantinopolitanum, T. rubens, and T. alpestre in various combinations. The successful embryo -rescue and development of hybrid plantlets requires skilled techniques of tissue culture and field practices. It includes hybridization in field; excision of hybrid embryos at appropriate stage; disinfection and culture in suitable culture media to allow maturation of embryo, multiplication of shoots, and rooting; hardening of the plantlets; inoculation with suitable Rhizobium culture; and transfer to field.