Rapid shoot multiplication of Nyctanthes arbor-tristis L. was achieved from axillary meristems on Murashige and Skoog (MS) basal medium supplemented with 1.0 -1.5 mg dm -3 6-benzylaminopurine (BA), 50 mg dm -3 adenine sulfate (Ads) and 3 % (m/v) sucrose. Inclusion of indole-3-acetic acid (IAA) in the culture medium along with BA + Ads promoted a higher rate of shoot multiplication. Maximum mean number of microshoots per explant (6.65) was achieved on the MS medium supplemented with 1.5 mg dm -3 BA, 50 mg dm -3 Ads and 0.1 mg dm -3 IAA after 4 weeks of culture. The elongated shoots rooted within 13 to 14 d on half-strength MS medium supplemented with either indole-3-butyric acid (IBA), IAA or 1-naphthaleneacetic acid (NAA) with 2 % sucrose. Maximum percentage of rooting was obtained on medium having 0.25 mg dm -3 IBA and 0.1 mg dm -3 IAA. About 70 % of the rooted plantlets survived in the greenhouse. The in vitro raised plants were grown normally in the field.Additional key words: growth regulators, medicinal plant, shoot multiplication. ⎯⎯⎯⎯Nyctanthes arbor-tristis Linn. is a valuable medicinal plant which belongs to the family Oleaceae, and is distributed in Indo-Malayan regions. It is a small tree with scented white flowers. It is a native of India occurring wild in the Sub-Himalayan region. Due to unrestricted large-scale exploitatiobn of the natural resource, coupled with limited cultivation and insufficient attempts for its replenishment, the natural stock of this species has been markedly depleted. Propagation from seed is unreliable due to poor germination and death of many young seedlings under natural conditions (Thapliyal and Naithani 1996). In vitro culture is an alternative method for conservation and propagation of this species, but no report has been published so far. Hence, this investigation aimed to develop an efficient protocol for micropropagation of N. arbor-tristis, an important medicinal plant.Elongated shoots (4 -5 cm long) were collected from field grown plants of Nyctanthes arbor-tristis L. and brought to the laboratory with cut ends dipped in distilled water. Stem without leaves were washed in 2 % (m/v) Teepol (Qualigen, Mumbai, India) and surface disinfected by 0.1 % (m/v) aqueous mercuric chloride solution for 15 min. After rinsing 4 -5 times with sterile distilled water, stems were cut into smaller segments (ca. 0.5 cm long), each with one node was used as explant source.Nodal explants were placed on semisolid Murashige and Skoog (1962; MS) mineral salts plus 555 µM myoinositol, 4.06 µM nicotinic acid, 2.43 µM pyridoxineHCl, 0.296 µM thiamine-HCl supplemented with various concentrations of cytokinins, i.e. 6-benzylaminopurine (BA: 0.0, 0.5, 1.0, 1.5 and 2.0 mg dm -3 ), kinetin (Kn: 0.0, 0.5, 1.0, 1.5 and 2.0 mg dm -3 ), adenine sulfate (Ads: 25, 50 and 100 mg dm -3 ) and auxins like indole-3-acetic acid (IAA: 0.0, 0.10, 0.25 and 0.5 mg dm -3 ) and 1-naphthalene-acetic acid (NAA: 0.0, 0.10, 0.25 and 0.5 mg dm -3 ) for shoot multiplication. The pH of the medium was adjusted to 5.8 prior...

Assessment of genetic diversity is a pre-requisite to broaden the genetic background of cultivated base of sweet corn, an endosperm mutant of field corn that alters starch biosynthesis pathway in endosperm. In the current investigation, genetic divergence among 39 inbred lines was assessed on the basis of 14 agro-morphological traits, two quality parameters and 63 microsatellite markers, selected on the basis of their association with QTLs affecting kernel quality. The cluster analysis based on unweighted pair-group method using arithmetic averages for agro-morphological and quality traits grouped the 39 inbreds into three clusters with 5, 14 and 20 genotypes, respectively. The unweighted neighbor-joining method for microsatellite markers also categorized the inbred lines into three major clusters grouping 10, 9 and 20 genotypes in cluster I, II and III, respectively. The two cluster distribution patterns showed approximately 36 percent similarity. The assay of 30 microsatellite repeats identified 82 alleles with allele size ranging from 80 to 400 bp. The major allele frequency and PIC value of the markers ranged from 0.42 to 0.79 and 0.27 to 0.63, respectively, which suggested the presence of high amount of polymorphism among the inbreds. The average heterozygosity was recorded to be 0.19 which signifies proper maintenance of inbred population. Principle co-ordinate analysis also depicted diverse nature of inbred lines and agreed well with the previously determined clustering pattern. This study has identified several inbreds, having good yield and high sugar content which will not only enhance the genetic background of sweet corn germplasm but will also lead to development of high-yielding hybrids with improved quality.

Intergeneric hybridization in seven diverse durum wheat genotypes was carried out using two composite varieties of Himalayan maize, viz., Bajaura Makka and Early Composite, and a wild grass, Imperata cylindrica, as pollen sources. Observations related to various haploid induction parameters put forth I. cylindrica as significantly better pollen source for haploid induction in durum wheat over maize in terms of pseudoseed formation (46.93%), embryo formation (38.06%), haploid regeneration (40.42%) and haploid formation efficiency (7.44%). The line x tester analysis revealed that both male and female genotypes had significant effects on all haploid induction parameters except haploid formation frequency in later. Among the pollen sources, I. cylindrica emerged as best combiner based on GCA values when compared with the two Himalayan maize composites. Durum wheat genotype, A-9-30-1 was recognized as the best general combiner followed by PDW 314. The present investigation proposed durum wheat 9 I. cylindrica as a superior technique over maize-mediated system, and its large-scale use can open a new horizon in the sphere of durum wheat doubled haploidy breeding programme.

Rapid shoot multiplication of Nyctanthes arbortristis was achieved from axillary meristems on Murashige and Skoog (MS) basal medium supplemented with 1.0-1.5 mg/l 6-benzyladenine (BA), 50 mg/l adenine sulfate (Ads) and 3% (m/v) sucrose. Inclusion of indole-3-acetic acid (IAA) in the culture medium along with BA + Ads promoted a higher rate of shoot multiplication. Maximum mean number of microshoots per explant (6.65) was achieved on the MS medium supplemented with 1.5 mg/l BA, 50 mg/l Ads and 0.1 mg/l IAA after 4 weeks of culture. The elongated shoots rooted within 13 to 14 days on ½ strength MS medium supplemented either with indole-3-butyric acid (IBA), IAA or naphtylacetic acid (NAA) with 2% sucrose. Maximum percentage of rooting was obtained on medium having 0.25 mg/l IBA, 0.1 mg/l IAA and 2% sucrose. About 70% of rooted plantlets survived in the greenhouse. The in vitro raised plants were grown normally in the soil condition. This result will facilitate the conservation and propagation of the important medicinal plant.

Unpredictable weather vagaries in the Asian tropics often increase the risk of a series of abiotic stresses in maize-growing areas, hindering the efforts to reach the projected demands. Breeding climate-resilient maize hybrids with a cross-tolerance to drought and waterlogging is necessary yet challenging because of the presence of genotype-by-environment interaction (GEI) and the lack of an efficient multi-trait-based selection technique. The present study aimed at estimating the variance components, genetic parameters, inter-trait relations, and expected selection gains (SGs) across the soil moisture regimes through genotype selection obtained based on the novel multi-trait genotype–ideotype distance index (MGIDI) for a set of 75 tropical pre-released maize hybrids. Twelve traits including grain yield and other secondary characteristics for experimental maize hybrids were studied at two locations. Positive and negative SGs were estimated across moisture regimes, including drought, waterlogging, and optimal moisture conditions. Hybrid, moisture condition, and hybrid-by-moisture condition interaction effects were significant (p ≤ 0.001) for most of the traits studied. Eleven genotypes were selected in each moisture condition through MGIDI by assuming 15% selection intensity where two hybrids, viz., ZH161289 and ZH161303, were found to be common across all the moisture regimes, indicating their moisture stress resilience, a unique potential for broader adaptation in rainfed stress-vulnerable ecologies. The selected hybrids showed desired genetic gains such as positive gains for grain yield (almost 11% in optimal and drought; 22% in waterlogging) and negative gains in flowering traits. The view on strengths and weaknesses as depicted by the MGIDI assists the breeders to develop maize hybrids with desired traits, such as grain yield and other yield contributors under specific stress conditions. The MGIDI would be a robust and easy-to-handle multi-trait selection process under various test environments with minimal multicollinearity issues. It was found to be a powerful tool in developing better selection strategies and optimizing the breeding scheme, thus contributing to the development of climate-resilient maize hybrids.