<i>In Vitro</i>Plant Regeneration of <i>Morus indica</i>L. cv. V1 Using Leaf Explant

Adventitious bud induction and plantlet regeneration were studied in a popular mulberry variety, V1 using leaf as an explant. Fully expanded leaf explants were cultured on Murashige and Skoog’s (MS) medium supplemented with thidiazuron (TDZ) (0.5-4.0 mg/l), 6-benzylaminopurine (BAP) (0.5-2.0 mg/l), indole acetic acid (IAA) (2.0 mg/l), gibberlic acid (GA3) (1.0-2.0 mg/l) silver nitrate (AgNO3) (2.0 mg/l) and different carbon sources such as sucrose, fructose and glucose (10%-30%) either individually or in combination to induce adventitious buds and regeneration. The highest percentage (63%) of adventitious bud formation and regeneration (68%) was achieved in the medium containing MS with TDZ (1.0 mg/l), IAA (2.0 mg/l) and AgNO3 (2.0 mg/l). For subsequent regeneration and shoot elongation the MS medium having BAP (1.0 mg/l), GA3 (2.0 mg/l) and AgNO3 (2.0 mg/l) was found to be suitable. Amongst the carbon sources tested, the most suitable carbon source was found to be sucrose (3%) followed by fructose (2%) for adventitious bud formation. Excised in vitro shoots were rooted (60%-80%) in half strength MS medium supplemented with indole-3-butyric acid (1.0 mg/l). The well rooted plantlets were hardened in soil + sand + farm yard manure (FYM) mixture with a success rate of 70%-90%. Since in vitro regeneration is highly genotype-dependent in mulberry, the standardized protocol can be effectively used for further improvement of this leading genotype using biotechnological approaches.

Variability, heritability and genetic advance in mulberry (<i>Morus</i>spp.) for growth and yield attributes

Genetic improvement of crop plants is brought about by manipulating the genetic makeup through systematic breeding techniques or by employing modern biotechnological tools. Application of systematic breeding technique to a large extent is decided by the knowledge on the genetic control of the traits. Keeping this in view, nine mulberry genotypes were evaluated for different growth and yield attributing traits viz., number of tillers (NT), plant height (PH), total shoot length (TSL), nodal distance (ND), leaf fall % (LF), number of leaves/plant (NLP), weight of 100 fresh leaves (WFL), weight of 100 dry leaves (WDL), single leaf area (LA), leaf area index (LAI), aboveground biomass (AGB), leaf harvest index (LHI) and leaf yield (LY) and estimated the magnitude of genotypic and phenotypic variation, heritability, genetic advance and correlation coefficients. The broad sense heritability for these traits ranged from 63.942 (WFL) to 13.261 (PH). High heritability coupled with high genetic advance was recorded for the characters WFL, LF, LA, WDL and LY suggesting the higher genetic control over these traits. Leaf yield showed significantly positive phenotypic and genotypic correlations with all other growth traits except PH and LF. Leaf fall had significant negative correlations with all the highly heritable yield attributes viz., ND (-0.379), WDL (-0.225), LA (-0.346), LAI (-0.233) at 1% level and AGB (-0.148), LHI (-0.122) and LY (-0.146) at 5% level. Likewise, it showed positive correlations with TSL (0.558), NLP (0.264) and PH (0.221). Since mulberry is mainly cultivated for leaf yield, genotypes having higher WFL, LA, WDL and LY and less LF must be given importance during parent selection to evolve high yielding varieties with less leaf fall across different seasons in mulberry.