Chromosomal assignment of AFLP markers in upland cotton (<Emphasis Type="Italic">Gossypium hirsutum</Emphasis> L.)

In this research, we used two sets of cotton aneuploid (G. hirsutum × G. tomentosum and G. hirsutum × G. barbadense) plants to locate AFLP markers to chromosomes using deletion analysis method. Thirty-eight primer combinations were used to generate 608 polymorphic AFLP markers. A total of 98 AFLP markers were assigned to 22 different cotton chromosomes or chromosome arms. Of those assigned markers, 63.3% were assigned to A genome and 36.7% were assigned to D genome. A low rate (14.3%) of common markers were found between those assigned AFLP markers with the AFLP markers from an intraspecific cross population developed previous in our lab. Based on the 16 common markers, we were able to associate the 13 linkage groups previously identified in our lab to eight chromosomes. Further research will be carried out by using SSR markers with known location to associate unassigned linkage groups to chromosomes.     

Sustainability Attributes of a Small-Scale Betel Leaf Agroforestry System: A Case Study in North-eastern Hill Forests of Bangladesh

The Khasia ethnic community of Bangladesh has been a population of forest villagers in the north-eastern hill forests of Bangladesh since the early 1950s, practicing a betel leaf-based agroforestry system on land granted by the Forest Department. Taking a sample forest village of the Sylhet forest division as a case study, this article examines the sustainability attributes of betel leaf production in the agroforestry system. The presence of several positive attributes of sustainability including the composition of agroforestry, disease control, soil fertility management, profitability, socio-cultural acceptability and institutional support indicate that betel leaf production within the agroforestry system is stable under the prevailing traditional management system. Income from the sale of betel leaf is the principal livelihood means and villager’s reciprocal contributions help to conserve forest resources. However, problems with land ownership and regular agreement renewal need to be resolved for the sake of their livelihoods and forest conservation.

Molecular characterization of endosperm and amino acids modifications among quality protein maize inbreds

Modifier loci in QPM play a vital role in achieving acceptable degree of kernel hardness and accumulation of lysine and tryptophan. This study was undertaken to characterize a set of diverse QPM inbreds using SSRs linked to endosperm and amino acids modifier loci for their effective utilization in the breeding programme. Significant variation was observed for endosperm modification (25–100% opaqueness), tryptophan (0.056–0.111%) and lysine (0.223–0.444%). Generally, inbreds with soft endosperm possessed more tryptophan and lysine than inbreds with higher vitreousness. SSRs generated 341 alleles with two to seven alleles per locus. The frequency of unique and rare alleles was more for amino acid modifications, compared to endosperm modifications. Phylogenetic analyses grouped the inbreds into three major clusters, and the study identified suitable crosses for accumulation of endosperm and amino acids modifiers. QPM inbreds with desirable modifications identified here would serve as suitable donor for both opaque2 and modifier loci in the marker‐assisted backcross breeding. Further, contrasting inbreds can be used for generating mapping populations to identify new modifier loci underlying both endosperm and amino acids modifications.     

Zinc delivery to plants through seed coating with nano-zinc oxide particles

In India, zinc (Zn) has been recognized as the fourth most important yield-limiting nutrient after nitrogen (N), phosphorus (P) and potassium (K). Supplementing the zinc (Zn) requirement of agricultural crops through water soluble zinc sulfate ZnSO₄ fertilizer is a costly management option whereas, utilization of ZnO (water insoluble and a cheaper material) as a source of Zn could be an alternative cost effective option to encourage farmers for wider adoption. In this present investigation, in order to supply the requisite amount of Zn to the plants, a protocol has been developed to coat the seeds of maize (Zea mays L.), soybean (Glycine max L.), pigeon pea (Cajanas cajan L.) and ladies finger (Abelmoschus esculentus L.) with microns scale (<3 µm) and nano-scale (<100 nm) ZnO powder at 25 mg Zn/g seed and at 50 mg Zn/g seed. Different Zn sources, ethyl alcohol, and crude pine oleoresin (POR) were used for coating of seeds. The germination test carried out with coated and uncoated seeds indicated better germination percentage (93–100%) due to ZnO coating as compared to uncoated seeds (80%). Pot culture experiment conducted with coated seeds also revealed that the crop growth with ZnO coated seeds were similar to that observed with soluble Zn treatment applied as zinc sulfate heptahydrate (ZnSO₄·7H₂O) (at 2.5 ppm Zn) which is evident from the periodic SPAD reading taken after 20, 25, 30 and 45 days after sowing. Application of Zn through different sources also enhanced the auxin indole-3-acetic acid (IAA) production in plant roots, which subsequently improved the overall growth. The most important advantage of seed coating with ZnO (both micron/nano-scale) is that it did not exert any osmotic potential at the time of germination of the seed, thus, the total requirement of Zn of the crop can be loaded with the seed effectively through nano-scale ZnO particle.     

Genomic resources for breeding crops with enhanced abiotic stress tolerance

To meet the challenges of climate change, exploring natural diversity in the existing plant genetic resource pool as well as creation of new mutants through chemical mutagenesis and molecular biology is needed for developing climate‐resilient elite genotypes. Ever‐increasing area under existing abiotic stresses as well as emerging abiotic stress factors and their combinations have further added to the problems of the current crop improvement programmes. However, with the advancement in modern techniques such as next‐generation sequencing technologies, it is now possible to generate on a whole‐genome scale, genomic resources for crop species at a much faster pace with considerably less efforts and money. The genomic resources thus generated will be useful for various plant breeding applications such as marker‐assisted breeding for gene introgression, mapping QTLs or identifying new or rare alleles associated with a particular trait. In this article, we discuss various aspects of generation of genomic resources and their utilization for developing abiotic stress‐tolerant crops to ensure sustainable agricultural production and food security in the backdrop of rapid climate change.     

Molecular mapping of black rot resistance locus Xca1bo on chromosome 3 in Indian cauliflower (Brassica oleracea var. botrytis L.)

Black rot is the most devastating disease of cauliflower worldwide causing severe damage to crop. The identification of markers linked to loci that control resistance can facilitate selection of plants for breeding programmes. In the present investigation, F₂ population derived from a cross between ‘Pusa Himjyoti’, a susceptible genotype, and ‘BR‐161’, a resistant genotype, was phenotyped by artificial inoculation using Xcc race 1. Segregation analysis of F₂ progeny indicated that a single dominant locus governed resistance to Xcc race 1 in ‘BR‐161’. Bulk segregant analysis in resistant and susceptible bulks of F₂ progeny revealed seven differentiating polymorphic markers (three RAPD, two ISSR and two SSR) of 102 markers screened. Subsequently, these markers were used to genotype the entire F₂ population, and a genetic linkage map covering 74.7 cM distance was developed. The major locus Xca1bo was mapped in 1.6‐cM interval flanked by the markers RAPD 04₈₃₃ and ISSR 11₆₃₅. The Xca1bo locus was located on chromosome 3. The linked markers will be useful for marker‐assisted resistance breeding in cauliflower.     

Cross-amplification of EST-derived markers among 16 grass species

The availability of a large number of expressed sequence tags (ESTs) has facilitated the development of molecular markers in members of the grass family. As these markers are derived from coding sequences, cross-species amplification and transferability is higher than for markers designed from genomic DNA sequences. In this study, 919 EST-based primers developed from seven grass species were assessed for their amplification across a diverse panel of 16 grass species including cereal, turf and forage crops. Out of the 919 primers tested, 89 successfully amplified DNA from one or more species and 340 primers generated PCR amplicons from at least half of the species in the panel. Only 5.2% of the primers tested produced clear amplicons in all 16 species. The majority of the primers (66.9%) were developed from tall fescue and rice and these two species showed amplification rate of 41.6% and 19.0% across the panel, respectively. The highest amplification rate was found for conserved-intron scanning primers (CISP) developed from pearl millet (91%) and sorghum (75%) EST sequences that aligned to rice sequences. The primers with successful amplification identified in this study showed promise in other grass species as demonstrated in differentiating a set of 13 clones of reed canary grass, a species for which very little genomic research has been done. Sequences from the amplified PCR fragments indicated the potential for the transferable CISP markers for comparative mapping purposes. These primer sets can be immediately used for within and across species mapping and will be especially useful for minor grass species with few or no available molecular markers.     

Bell pepper yield and soil properties during conversion from conventional to organic production in Indian Himalayas

A conversion period of at least two years is required for annual crops before produce may be certified as organically grown. There is a need for better understanding of the various management options for implementing from conventional to organic production. The purpose of this study was to evaluate the effects of three organic amendments on growth and yield of bell pepper (Capsicum annuum L.), the benefit:cost ratio, soil fertility and enzymatic activities during conversion to organic production. For that purpose six treatments were established: composted farmyard manure (FYMC, T₁); vermicompost (VC, T₂); poultry manure (PM, T₃) along with biofertilizers (BF) [Azotobacter + phosphorus solubilizing bacteria (Pseudomonas striata)] and mix of three amendments (FYMC + PM + VC + BF, T₄); integrated crop management (FYMC + NPK, T₅) and unamended control (T₆). The bell pepper yield under organic management was markedly lower (33–53% and 18–40% less in first and second year of conversion, respectively) than with the integrated crop management (FYMC 10 Mg ha⁻¹ + NPK – 100:22:41.5 kg ha⁻¹) treatment (T₅). Combined application of three organic amendments (FYMC 10 Mg ha⁻¹ + PM and VC each 1.5 Mg ha⁻¹ + BF, T₄) and T₁ produced similar but significantly higher bell pepper yield (27.9 and 26.1 Mg ha⁻¹, respectively) compared with other organic amendment treatments. Both T₄ and T₁ greatly lowered soil bulk density (1.15–1.17 Mg m⁻³), and enhanced soil pH (7.1) and oxidizable organic carbon (1.2–1.3%) compared with T₅ and unamended control (T₆) after a two-year transition period. However, the N, P and K levels were highest in the plots under integrated management. T₁ plots showed higher dehydrogenase activity values. However, acid phosphatase and β-glucosidase activities were higher in T₆ plots whereas urease activity was greater in T₅ plots compared with other treatments. Among the treatments involving organic amendments alone, T₁ gave a higher gross margin (US $ 8237.5 ha⁻¹) than other treatments. We conclude that T₁ was found more suitable for enhancing bell pepper growth and yield, through improved soil properties, during conversion to organic production.     

Determining critical limit of boron in soil for wheat (Triticum aestivum L.)

Abstract

Critical values of boron (B) for wheat nutrition in soil and plant were determined through a pot experiment with twenty-one surface soils of Alluvial flood plain and Red-latertic belt comprising three major soil orders (Entisols, Alfisols, Inceptisols) with four levels of boron. Application of boron significantly increased the dry matter yield as well as uptake of B by plants. Critical concentration of hot calcium chloride (CaCl₂) extractable B in soil for wheat was found to be 0.53?mg?kg^?1. The critical plant B concentration varied with growth stages and values were 7.4?mg?kg^?1 at panicle initiation and 4.18?mg?kg^?1 at maturity, respectively. The findings of this investigation also recommend the application of 2?kg?B^?1?ha^?1 for ensuring B sufficiency to wheat in Indo-gangetic alluvial and Red-Lateritic soils.