QTL analysis for grain weight in common wheat

Quantitative trait loci (QTL) analysis for grain weight (GW = 1000 grain weight) in common wheat was conducted using a set of 100 recombinant inbred lines (RILs) derived from a cross ‘Rye Selection 111 (high GW) × Chinese Spring (low GW)’. The RILs and their two parental genotypes were evaluated for GW in six different environments (three locations × two years). Genotyping of RILs was carried out using 449 (30 SSRs, 299 AFLP and 120 SAMPL) polymorphic markers. Using the genotyping data of RILs, framework linkage maps were prepared for three chromosomes (1A, 2B, 7A), which were earlier identified by us to carry important/major genes for GW following monosomic analysis. QTL analysis for GW was conducted following genome-wide single marker regression analysis (SMA) and composite interval mapping (CIM) using molecular maps for the three chromosomes. Following SMA, 12 markers showed associations with GW, individual markers explaining 6.57% to 10.76% PV (phenotypic variation) for GW in individual environments. The high grain weight parent, Rye Selection111, which is an agronomically superior genotype, contributed favourable alleles for GW at six of the 12 marker loci identified through SMA. The CIM identified two stable and definitive QTLs, one each on chromosome arms 2BS and 7AS, which were also identified through SMA, and a third suggestive QTL on 1AS. These QTLs explained 9.06% to 19.85% PV for GW in different environments. The QTL for GW on 7AS is co-located with a QTL for heading date suggesting the occurrence of a QTL having a positive pleiotropic effect on the two traits. Some of the markers identified during the present study may prove useful for marker-assisted selection, while breeding for high GW in common wheat.     

Genetic transformation of pigeonpea with rice chitinase gene

With a long‐term plan to develop transgenic pigeonpea with resistance to fungal disease, the transfer of a rice chitinase gene to pigeonpea [Cajanus cajan (L.) Millsp.] is reported here. The rice chitinase gene harboured in the plasmid pCAMBIA 1302:RChit was delivered via the Agrobacterium‐mediated method to the cotyledonary node explants followed by subsequent regeneration of complete plants on selection media containing hygromycin. Putative transformed pigeonpea plants were recovered with stringent selection pressure and confirmed using molecular techniques. Stable integration and expression of the chitinase gene has been confirmed in the T0 and T1 transgenics through molecular analysis.     

Breeding and evaluation of Digitaria eriantha for improved spring yield and seed production

Summary Digitaria eriantha is a subtropical grass which is widely sown as a pasture species in South Africa and cultivars have recently been released in Australia. The species is variable in seed production and in other agronomic attributes. This paper describes a breeding program designed to combine the seed production of cv. Premier with the high productivity in winter-spring of an almost sterile genotype.Hybrids between the two accessions were either triploid and sterile, or diploid with low fertility. The F₂ to F₅ generations were selected intensively for fertility and, at two contrasting sites, for spring productivity, with both maternal and paternal selection. The F₆ generation was grown as replicated swards and yield in spring, and fertility, were used for selection of elite F₅ plants to comprise the parents of a new cultivar (cv. Advance).In evaluation trials, spring dry matter production of Advance averaged 40% higher than that of Premier. On average, seed production of Advance was 11% lower than that of Premier and botanical fertility was consistently about half that of Premier. Experimental yields of cleaned seed of Advance were up to 138 kg/ha. In commerce, seed yields of Advance are likely to be lower than those of Premier unless higher inflorescence densities than Premier can be achieved.     

Prenylated flavanones isolated from flowers of Azadirachta indica (the neem tree) as antimutagenic constituents against heterocyclic amines

Four prenylated flavanones were isolated from the methanol extract of the flowers of Azadirachta indica (the neem tree) as potent antimutagens against Trp-P-1 (3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole) in the Salmonella typhimurium TA98 assay by activity-guided fractionation. Spectroscopic properties revealed that those compounds were 5,7,4'-trihydroxy-8-prenylflavanone (1), 5,4'-dihydroxy-7-methoxy-8-prenylflavanone (2), 5,7,4'-trihydroxy-3',8-diprenylflavanone (3), and 5,7,4'-trihydroxy-3',5'-diprenylflavanone (4). All isolated compounds were found for the first time in this plant. The antimutagenic IC(50) values of compounds 1-4 were 2.7 +/- 0.1, 3.7 +/- 0.1, 11.1 +/- 0.1, and 18.6 +/- 0.1 microM in the preincubation mixture, respectively. These compounds also similarly inhibited the mutagenicity of Trp-P-2 (3-amino-1-methyl-5H-pyrido[4,3-b]indole) and PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine). All of the compounds 1-4 strongly inhibited ethoxyresorufin O-dealkylation activity of cytochrome P450 1A isoforms, which catalyze N-hydroxylation of heterocyclic amines. However, compounds 1-4 did not show significant inhibition against the direct-acting mutagen NaN(3). Thus, the antimutagenic effect of compounds 1-4 would be mainly based on the inhibition of the enzymatic activation of heterocyclic amines.     

Micronutrients (Fe,Mn, Zn and Cu) balance under long-term application of fertilizer and manure in a tropical rice-rice system

Purpose

The balance of micronutrients in soils is important in nutrient use efficiency, environmental protection and the sustainability of agro-ecological systems. The deficiency or excess of micronutrients in the plough layer may decrease crop yield and/or quality. Therefore, it is essential to maintain appropriate levels of micronutrients in soil, not only for satisfying plant needs in order to sustain agricultural production but also for preventing any potential build-up of certain nutrients.

Materials and methods

A long-term fertilizer experiment started in 1969 at Central Rice Research Institute, Cuttack, Odisha, India. Using this experiment, a study was conducted to analyze the balance of micronutrients and their interrelationship. The experiment was composed of ten nutrient management treatments viz. control; nitrogen (N); N + phosphorus (NP); N + potassium (NK); nitrogen, phosphorus and potassium (NPK); farmyard manure (FYM); N + FYM; NP + FYM; NK + FYM; and NPK + FYM with three replications. Micronutrients in soil (total and available), added fertilizers and organic manures and in rice plant were analyzed. Besides, atmospheric deposition of the micronutrients to the experimental site was also calculated. A micronutrient balance sheet was prepared by the difference between output and input of total micronutrients.

Results and discussion

Application of FYM alone or in combination with chemical fertilizer increased the diethylenetriamine pentaacetate (DTPA)-extractable Fe, Mn and Zn over the control treatment. The treatment with NPK + FYM had the highest soil DTPA-extractable Fe, Mn, Zn and Cu after 41 years of cropping and fertilization. Application of chemical fertilizers without P decreased the DTPA-extractable Zn over the control while the inclusion of P in the fertilizer treatments maintained it on a par with the control. The application of P fertilizer and FYM either alone or in combination significantly increased the contents of total Fe, Mn, Zn and Cu in soil mainly due to their micronutrient content and atmospheric depositions. A negative balance of Zn was observed in the N, NP, NK and NPK treatments, while a positive balance observed in the remaining treatments. The balance of Mn was negative in all the treatments, due to higher uptake by the rice crop than its addition.

Conclusions

Long-term application of chemical fertilizers together with FYM maintained the availability of micronutrients in soil and, thus, their uptake by rice crop.

     

Influence of earthworm culture on fertilization potential and biological activities of vermicomposts prepared from different plant wastes

The present investigation was aimed to analyze influence of earthworm culture on nutritive status, microbial population, and enzymatic activities of composts prepared by utilizing different plant wastes. Vermicomposts were prepared from different types of leaves litter of horticulture and forest plant species by modified vermicomposting process at a farm unit. Initial thermophilic decomposition of waste load using cow‐dung slurry was done in the separate beds. The culture of Eisenia fetida was used for vermicomposting in specially designed vermibeds at the farm unit. The physico‐chemical characteristics, enzyme activities (oxido‐reductases and hydrolases), and microbial population (bacteria, fungi, free‐living nitrogen‐fixing bacteria, actinomycetes, Bacillus, Pseudomonas, phosphate‐solubilizing bacteria and fungi) of vermicomposts were found significantly higher (p < 0.05) than those of control (without earthworm inoculum). The study quantified significant contributions of earthworm culture to physico‐chemical, enzymatic, and microbiological properties of vermicompost and confirmed superior fertilization potential of vermicompost for organic farming. The agronomic utility of vermicompost was assessed on yellow mustard plant in a pot experiment. Pot soil was amended with different ratios (5%, 10%, 20%) of vermicompost and normal compost (without earthworm inoculum). Effects of these amendments on the growth of Brassica comprestis L. were studied. The significant differences (p < 0.05) in the growth of plant were observed among vermicompost‐, compost‐amended soil, and control. Vermicompost increased the root and shoot lengths, numbers of branches and leaves per plant, fresh and dry weights per plant, numbers of pods and flowers, and biochemical properties of plant leaf significantly, especially in 20% amendment. These results proved better fertilization potential of vermicompost over non‐earthworm‐inoculated compost.     

Yeast extract, brewer’s yeast and spirulina in diets for Labeo rohita fingerlings affect haemato-immunological responses and survival following Aeromonas hydrophila challenge

A feeding trial was conducted for 60 days to study the immunomodulatory role of three different immunostimulants yeast extract (YE), brewer’s yeast (BY) and spirulina (SP) in Labeo rohita fingerlings. Four hundred and fifty fingerlings (avg. wt 3.35 ± 0.15 g) were randomly distributed in ten treatments and fed with either of ten iso-nitrogenous and iso-caloric semi-purified diets, prepared with three incremental levels (1%, 2% and 4%) of different immunostimulants except the control. Growth parameters did not vary significantly (p > 0.05) among the experimental groups. Haematology and serum parameters was performed before Aeromonas hydrophila challenge whereas respiratory burst activity was analysed following challenge. The respiratory burst activity, total leucocyte count, serum total protein and globulin was significantly higher (p < 0.05) in YE 1% supplemented group. The survival (%) after challenging with A. hydrophila was also highest in the YE fed groups. The results indicate that among the different sources and levels of immunostimulants, YE at lower inclusion level is more effective in promoting the immune status of L. rohita fingerlings.     

Genome organization in coffee as revealed by EST PCRRFLP,SNPs and SSR analysis

An EST-based PCR-RFLP method was employed to gain insight into genome organization in eight allopolyploid Coffea arabica cultivars and seven diploid coffee species. The PCR-amplified products at 19 EST loci were digested with 46 different restriction enzymes and size fractioned in agarose gels. Most often, the sum of the fragments length was double or more than the PCR product. In arabica, this condition could be explained by assuming the presence of duplicated loci in paralogous chromosomes and this was supported by considerable evidence of multiple loci SSR amplification. Based on the RFLP analysis, 12 EST loci were polymorphic. The level of polymorphism was higher in different species compared to the arabica varieties. Sequencing of the amplified products revealed a SNP frequency of 0.021 among diploid species and of 0.007 among arabica varieties. We propose that the involvement of two genomes in C. arabica maintains a residual level of heterozygosity in the form of paralogous chromosomes, while the self-fertilization in this species tends to drive of homozygosity. The heterozygosity of paralogous chromosomes in arabica creates valuable polymorphism essential for species diversity and survival in various ecological niches, while self-fertility tends to preserve in homozygosity many genes of functional significance.     

Monitoring the pollution risk and water use in orchard terraces with mango and cherimoya trees by drainage lysimeters

Agricultural nonpoint-source pollution is the leading cause of water-quality degeneration of rivers and groundwater. In this context, the coast of Granada province (SE Spain) is economically an important area for the subtropical fruit cultivation. This intensively irrigated agriculture often uses excessive fertilizers, resulting to water pollution. Therefore, a 2-year experiment was conducted using drainage lysimeters to determine the potential risk of nutrient pollution in mango (Mangifera indica L. cv. Osteen) and cherimoya (Annona cherimola Mill. cv. Fino de Jete) orchards. These lysimeters were used to estimate the nutrient budgeting for each crop. NO₃-N, NH₄-N, PO₄-P and K losses according to lysimeters were, respectively, 55.1, 12.4, 3.7, and 0.6 for mango and 61.8, 17.8, 4.9, and 0.5 kg ha⁻¹ yr⁻¹, for cherimoya. NO₃, concentrations in the leachates ranged from 1.8 to 44.3 mg L⁻¹, and from 23.0 to 51.0 mg L⁻¹, for mango and cherimoya, respectively, in some cases exceeding the limits for safe drinking water. PO₄ also exceeded the permitted concentrations related to eutrophication of water, ranging from 0.07 to 0.5 mg L⁻¹ and from 0.12 to 0.68 mg L⁻¹ from mango and cherimoya lysimeters, respectively. With respect to the nutrient balance, N, P, and K removed by cherimoya fruits was 76.4, 5.5, and 22.6 kg ha⁻¹ yr⁻¹, and for mango fruits 30.2, 3.3 and 27.8 kg ha⁻¹ yr⁻¹, respectively. Nutrient losses in the leachates were surprisingly low, considering total N, P, and K applied during the year, in mango lysimeters 3.8, 0.11, and 12.6%, and in cherimoya lysimeters 7.7, 0.23 and 16.0%, respectively, indicating a potential soil accumulation and eventual loss risk, especially during torrential rains. Crop coefficient (Kc) values of mango trees varied within ranges of 0.35–0.67, 0.55–0.89, and 0.39–0.80 at flowering, fruit set, and fruit growth, respectively. Kc values for cherimoya trees had ranges of 0.58–0.67, 0.61–0.68, and 0.43–0.62 at flowering, fruit set and fruit growth, respectively. In this study, the Kc values of mango and cherimoya were significantly correlated to julian days. Therefore, the estimated WUE in the mango and cherimoya orchards reached 21.2 and 14.0 kg ha⁻¹ mm⁻¹, respectively. Thus, this study highlights the urgency to establish the optimal use of fertilizers and irrigation water with respect to crop requirements, to preserve surface-water and groundwater quality, thereby achieving more sustainable agriculture in orchard terraces.