Variability among isolates of <Emphasis Type="Italic">Fusarium udum</Emphasis> and the effect on progression of wilt in pigeonpea

Soft rot of Chinese cabbage is a disease of great economic importance to the State of Pernambuco, Brazil. The present study aimed to evaluate the effect of two calcium sources in different concentrations (calcium nitrate [Ca(NO₃)₂] at 0, 0.15 and 0.3 g l^?1 and calcium chloride (CaCl₂) at 0, 1 and 5 g l^?1) that were applied through two methods (leaf spraying and soil drenching) on the control of soft rot. Further, it aimed to analyze calcium absorption by the plant and to determine calcium’s role in leaf and cell structure using microscopy. Ca(NO₃)₂ applied by both methods was effective in controlling soft rot caused by Pectobacterium carotovorum subsp. carotovorum, as it reduced the disease by up to 48.5 % when sprayed onto the leaves (0.15 g l^?1). A significant increase in the leaf calcium content was observed only in the plants that were sprayed with higher doses of Ca(NO₃)₂ and CaCl₂. In all of the calcium treatments, light microscopy analyses revealed an increased number of chloroplasts and improved structuring of the palisade parenchyma, while transmission electron microscopy analyses revealed an increased cell wall thickness that was especially evident for the 0.15 g l^?1 Ca(NO₃)₂ treatment applied by leaf spraying and soil drenching.     

Soil enzymatic activity as affected by long term application of farm yard manure and mineral fertilizer under a rainfed soybean–wheat system in N-W Himalaya

Long-term experimental sites are expected to provide important information regarding soil properties as affected by management practices. This study was designed to examine the effects of continuous fertilization, and manuring on the activities of enzymes involved in mineralization of C, N, and P on a long term (33 years) field trial under sub-temperate conditions in India. Treatments at the site included application of recommended doses of nitrogen and phosphorus (NP), nitrogen and potassium (NK), nitrogen, phosphorus and potassium (NPK), farmyard manure (FYM) with N (N + FYM), FYM with NPK (NPK + FYM) and un-amended control (C). The study was done under rainfed soybean–wheat rotation. Manure application increased soil carbohydrate, dehydrogenase, acid and alkaline phosphatases, cellulase, and protease activity significantly. Urease activity was not influenced by the manure treatment and the activity was highest in controls. Both acid and alkaline phosphatase activities were negatively influenced by chemical fertilizer treatment. Almost all the enzymes studied were significantly correlated with soil C content. The results suggest that application of FYM directly or indirectly influences the enzyme activity and it in turn regulates nutrient transformation.     

Buffalo heifers selected for lower residual feed intake have lower feed intake,better dietary nitrogen utilisation and reduced enteric methane production

This study was conducted to evaluate the utilisation of the residual feed intake (RFI ) as a feed efficiency selection tool and its relationship with methane emissions. Eighteen Murrah buffalo (Bubalus bubalis ) heifers were fed ad libitum with total mixed ration (TMR ) for 120 days. Based on linear regression models involving dry matter intake (DMI ), average daily gain (ADG ) and mid‐test metabolic body size (MBW ^0.75), heifers were assigned into low and high RFI groups. The RFI varied from ?0.09 to +0.12 kg DM /day with average RFI of ?0.05 and 0.05 kg DM /day in low and high RFI heifers respectively. Low RFI heifers ate 11.6% less DM each day, yet average daily gain (ADG ) and feed utilisation were comparable among low and high RFI groups. Low RFI heifers required significantly (p  < .05) less metabolizable energy for maintenance (ME m) compared to high RFI heifers. Apparent nutrient digestibility showed non‐significant difference (p >  .05) among low and high RFI groups. Although the nitrogen balance was similar among heifers of low and high RFI groups, nitrogen metabolism was significantly higher (p  > .05) in high RFI heifers. Comparison of data from heifers exhibiting the low (n  = 9) and high (n  = 9) RFI showed that the low RFI heifers have lower enteric methane production and methane losses than high RFI heifers. In conclusion, results of this study revealed that selection of more efficient buffalo heifers has multiple benefits, such as decreased feed intake and less emission of methane.     

Influence of irrigation frequencies and phosphate fertilization on actual evapotranspiration rate, yield and water use pattern of rajmash (Phaseolus vulgaris L.)

The hypothesis was tested, whether soil wetness and phosphorus status could regulate the evapotranspiration rate (ET_R), which is of special interest in the lower Gangetic Plain. Rajmash was grown during November-February of 2003-2004 and 2004-2005 on a sandy loam soil, and was irrigated when cumulative pan evaporation (CPE) attained the value of 33 mm (CPE₃₃); 44 mm (CPE₄₄) and 66 mm (CPE₆₆). Four levels of phosphate application were 0 kg P₂O₅ ha⁻¹ (P₀); 30 kg P₂O₅ ha⁻¹ (P₃₀); 60 kg P₂O₅ ha⁻¹ (P₆₀) and 90 kg P₂O₅ ha⁻¹ (P₉₀). Seed yield under CPE₃₃ was 1.37 Mg ha⁻¹ and reduced by 18% and 35%, respectively under CPE₄₄ and CPE₆₆. Continuous increasing trend in yield was recorded with an increase in phosphate level (PL). Irrespective of growth stages, similar trends were recorded for leaf area index (LAI). Maximum variation in LAI among the treatments was recorded at 60 days after sowing. On average, actual ET_R was 1.37 mm day⁻¹ under CPE₃₃ and declined by 13% and 16% under CPE₄₄ and CPE₆₆, respectively. Variation in ET_R under different PL was highest under CPE₃₃ and lowest under CPE₄₄. Except P₉₀, irrespective of PL, highest value of water use efficiency (WUE) was obtained under CPE₄₄. However, magnitude of net evapotranspiration efficiency (WUE_ET) and irrigation efficiency (WUE_I) attained the highest level under CPE₃₃ regime. All water use indices showed an increasing trend with the increase in phosphate level from 0 to 90 kg ha⁻¹. Impact of phosphorus on various parameters was pronounced under CPE₃₃.     

Simultaneous detection of stone fruit tree viruses by one-step multiplex RT-PCR

A protocol of multiplex RT-PCR in a one-tube system for the detection of the most common stone fruit trees viruses [e.g., plum pox virus (PPV), prune dwarf virus (PDV), and Prunus necrotic ringspot virus (PNRSV)], including the internal control of NADH dehydrogenase subunit 5 (nad5) gene are described here. The method specificity was tested on more than 80 different samples with various isolates and strains of the viruses. It showed that the targeted viruses produced the expected amplicons, whereas all other related viruses produced only the nad5 internal control amplicon. The method sensitivity was evaluated by comparing it with Simplex RT-PCR with the same primers; no significant differences in detection limits were recorded. Furthermore, the competitiveness of the primers in the assay was tested by serial RNA dilutions of samples with mixed and single infections. The least competitive was the internal control nad5 gene primer pair; therefore, there is a reduced risk of false negatives as all the other primers tend to be more efficient in the given primer cocktail than in the primers for internal control.     

Karyotype analysis and chromosomal evolution in Asian species of Corchorus (Malvaceae s. l.)

Here, we report the karyotypes and mean haploid idiograms of the ten Asian Corchorus species (2n = 2x = 14). Chromosomes were small, with a mean chromosome length of 2.30 μm. The largest chromosome was recorded in C. pseudo-olitorius (3.50 μm) and the shortest in C. pseudocapsularis (1.60 μm). The karyotypes of the two cultivated species (C. capsularis and C. olitorius) and C. pseudo-olitorius were the most diverse and specialized, whereas those of C. depressus and C. trilocularis were the least diverse. C. fascicularis had the most asymmetrical and C. urticifolius the most symmetrical karyotypes. An increase in genome size was accompanied by increasing karyotype diversity in terms of morphologically distinct chromosome types and interchromosomal asymmetry, with uneven distribution of additional DNA throughout the karyotype. A positive correlation between interchromosomal asymmetry and dispersion index suggested that size differences between chromosomes were mainly associated with karyotype asymmetry. Karyotypes of the Corchorus species became progressively asymmetrical in the course of evolution. Relationships among the ten Corchorus species were defined by using a neighbor-joining tree inferred from inter-simple sequence repeat data. C. fascicularis and C. pseudocapsularis, with shorter karyotypes and smaller genomes, were closely related to C. pseudo-olitorius and C. capsularis, respectively, which were characterized by relatively longer karyotypes and larger genomes. However, the two cultivated species with different levels of interchromosomal asymmetries, dispersion indices and genome sizes were distantly related. Taking this molecular evidence into consideration, we have discussed chromosomal evolution in relation to karyological data including genome size.     

LONG‐TERM MANURING AND FERTILIZER EFFECTS ON DEPLETION OF SOIL ORGANIC CARBON STOCKS UNDER PEARL MILLET‐CLUSTER BEAN‐CASTOR ROTATION IN WESTERN INDIA

Soil organic carbon (SOC) pools are important for maintaining soil productivity and reducing the net CO₂ loading of the atmosphere. An 18‐year old long‐term field experiment involving pearl millet‐cluster bean‐castor sequence was conducted on an Entisol in western India to examine the effects of chemical fertilizers and manuring on carbon pools in relation to crop productivity and C sequestration. The data showed that even the addition of 33.5 Mg ha⁻¹ C inputs through crop residues as well as farm yard manure could not compensate the SOC depletion by oxidation and resulted in the net loss of 4.4 Mg C ha⁻¹ in 18 years. The loss of SOC stock in the control was 12 Mg C ha⁻¹. Conjunctive use of chemical fertilizers along with farm yard manure produced higher agronomic yields and reduced the rate of SOC depletion. The higher average seed yields of pearl millet (809 kg ha⁻¹), cluster bean (576), and castor (827) over six cropping seasons were obtained through integrated use of fertilizers and manure. For every Mg increase in profile SOC stock, there was an overall increase of 0.46 Mg of crop yield, comprising increase in individual yield of pearl millet (0.17 Mg ha⁻¹ y⁻¹ Mg⁻¹ SOC), cluster bean (0.14) and castor (0.15). The magnitude of SOC build up was proportional to the C inputs. Carbon pools were significantly correlated with SOC, which increased with application of organic amendments. Threshold C input of 3.3 Mg C ha⁻¹ y⁻¹ was needed to maintain the SOC stock even at the low antecedent level. Copyright © 2011 John Wiley & Sons, Ltd.     

Direct monitoring of Rhizobium sp. (Cicer) in nodules and soil using lac Z fusions

We constructed lacZ fusions in Rhizobium sp. (Cicer) by random Tn5-lacZ mutagenesis. The lacZ⁺ fusants formed blue colonies on a Rhizobial minimal medium containing 5-bromo-4-chloro-3-indolyl--D-galactopyranoside (X-gal). Rhizobium sp. (Cicer) fusant HSL-2 was identified in nodules and soil in a mixed population on the basis of the lacZ⁺ phenotype. Nodule occupancy of inoculated Rhizobium sp. (Cicer) HSL-2 (lacZ⁺) was assessed by directly streaking the nodule sap on X-gal plates. This method revealed differences between rhizobia carrying identical antibiotic markers. The rhizobial population in soil was estimated by direct plate counts using a medium containing X-gal. Introduction of lacZ into the Rhizobium sp. thus provided a simple and direct method for identifying strains from nodules and soil.