Prospects and challenges in utilization of indigenous rocks and minerals as source of potassium in farming

Potassium (K) is one of the essential nutrients required by crops in large quantities; however, its use in agriculture by farmers is less than required in developing countries. This neglect has led to excess mining of K in soils by crop plants and has resulted in a negative balance of K in soils. This loss necessitates the need of more use of potassium fertilizers in agriculture. Rocks and minerals offer a potential fertilizer to utilize in agriculture as source of K. The crop trials revealed that feldspar, mica, glauconite, nepheline and shoenite are good sources of K for crops, especially in highly weathered acid soils. However, some researchers have reported no agronomic benefit of feldspar or granite rock application to crops. Overall the size modification, acidulation, microbial inoculants and preparation of K-enriched compost are the effective techniques to utilize K-bearing rocks and minerals. Very limited information is available on these aspects. Thus, in this review, an attempt has been to consolidate up-to-date information of indigenous rocks and minerals as possibilities for alternate sources of K for crop plants. Moreover, this area of research needs attention to utilize indigenous K sources, which can aid to limit the import and cost, of the establishment of potash fertilizer-based industries in developing countries.     

Rapid detection of Corynebacterium pseudotuberculosis in clinical samples from sheep

Corynebacterium pseudotuberculosis, a Gram-positive bacterium is the causative agent of caseous lymphadenitis (CLA), a chronic disease of sheep, goats and other warm blooded animals. In the present study, a total of 1,080 sheep reared under semi-intensive system on organized farms situated in the semi arid tropical region of Rajasthan, India, was clinically examined. Pus samples from superficial lymph nodes of 25 (2.31 %) adult sheep showing clinical lesions similar to CLA were collected for laboratory analyses. On the basis of morphological, cultural and biochemical characteristics 12 (48 %) bacterial isolates from pus identified it as C. pseudotuberculosis. A polymerase chain reaction (PCR) assay targeting Putative oligopeptide/dipeptide ABC transporter, nicotinamide adenine dinucleotide phosphate (NADP) oxidoreductase coenzyme F420-dependent and proline iminopeptidase (PIP) genes of C. pseudotuberculosis was developed that showed 14 pus samples as positive. All C. pseudotuberculosis isolates were also found positive for these genes in the PCR. The specificity of the PCR products was confirmed by sequencing of the amplified products that showed 98–100 % homology with published sequences available in the NCBI database. The present study shows the incidence of CLA as 2.31 %, 1.1 % and 1.29 % based on clinical, bacterial culture and direct pus PCR assay, respectively. The PCR assay was rapid, specific and as significant as bacterial culture in detecting bacteria directly in the clinical pus samples. The PCR assay developed in the study can be applied for the diagnosis and control of CLA. Furthermore, the assay can also be applied to detect C. pseudotuberculosis in various clinical samples.     

Hepatoprotective activity of Vitex negundo leaf extract against anti-tubercular drugs induced hepatotoxicity

Hepatoprotective (HP) activity of Vitex negundo (VN) leaf ethanolic extract was investigated against hepatotoxicity (HT) produced by administering a combination of three anti-tubercular drugs isoniazid (INH)-7.5 mg/kg, rifampin (RMP)-10 mg/kg and pyrazinamide (PZA)-35 mg/kg for 35 35 days by oral route in rats. V. negundo leaf ethanolic extract was administered in three graded doses of 100, 250 and 500 mg/kg orally, 45 min prior to anti-tubercular challenge for 35 days. HP effect of V. negundo leaf ethanolic extract was evident in the doses of 250 and 500 mg/kg as there was a significant decrease in TB, AST, ALT and ALP levels in comparison to control. Histology of the liver section of the animals treated with the V. negundo leaf ethanolic extract in the doses of 250 and 500 mg/kg further confirms the HP activity.     

Assessment of Methods for Measuring Soil Microbial Biomass Carbon in Temperate Fruit Tree-Based Ecosystems

We investigated the potential of three methods of quantifying microbial biomass carbon (MBC), viz., chloroform fumigation-extraction (CFE) following organic C estimation through Vance method (CFE-V) and Snyder–Trofymow method (CFE-ST), and substrate-induced respiration (SIR) method in soils under various temperate fruit crops along with a control (no plantation) at 0–20 and 21–40 cm soil depths. CFE methods have shown significant (p < 0.05) increase in chloroform labile C in all orchards over the control in surface soil. The interaction between the fruit crops and methods, although significant (p < 0.01), indicated that CFE-ST and SIR methods were statistically at par with each other within the same fruit crop, except peach plantation (CEF-ST significantly lower than SIR) in 0–20 cm soil depth. The coefficient of variation recorded for chloroform labile organic C estimates by CFE-ST method makes it more precise than CFE-V method, especially in 0–20 cm soil depth. The very close agreement between the methods suggests that over this narrower range (i.e., smaller geographical area) all methods are appropriate for assessing MBC. However, SIR, being most sensitive to orchard plantations and strongly correlated with various soil chemical properties, could preferably be recommended for estimation of MBC in such soils. As an alternative to CFE-V method, CFE-ST may also be used for estimation of chloroform labile organic C in these soils.     

Micropropagation of Cymbidium Sleeping Nymph through protocorm-like bodies production by thin cell layer culture

Transverse thin cell layers (tTCLs) of protocorm-like bodies of two stages of PLBs (30 d and 60 d old) of Cymbidium Sleeping Nymph were used as explants to induce PLBs by using coconut water (CW) as a natural additive. 5% (v/v) CW supplemented to KC medium induced an average of 5 PLBs per responding tTCL of 30 d old PLBs with 83% of responding tTCLs. A low percentage of responding tTCLs were observed in 60 d old PLBs’ tTCLs. Anatomical and confocal microscopic studies traced the origin of PLBs to subepidermal layers of the tTCL. A significantly high percentage of shoot regeneration was obtained from PLBs formed on 1–10% (v/v) CW from tTCLs of 30 d old PLBs in comparison to PLBs induced on control after first subculture on KC medium (without CW). The induced PLBs regenerated into plantlets with velamenous roots and these plantlets were transferred to greenhouse conditions on cocopeat:perlite (9:1) with nearly 100% survival. Post-transfer performance of the plantlets was monitored. The results suggest tTCLs as potential explants (with respect to economy of precious hybrid materials) which can overcome the slow growth of hybrid PLBs and coconut water as a single natural additive for the mass multiplication of commercially important orchids.     

Pruned tea bushes secrete more root exudates to influence microbiological properties in soil

Pruning is adopted at 3–4 years interval as an agronomic practice during tea cultivation. It was hypothesized that biomass loss during pruning will imply stress on tea bushes. The aim of this study was to quantify changes in different parameters (labile organic carbon fractions, phosphatase activity, microbial biomass and microbial respiration) in tea rhizosphere due to pruning by collecting soil samples from the rhizosphere of ten of each pruned and un-pruned tea bushes. Hot-water extractable and dissolved organic C contents in rhizosphere soil of pruned tea were significantly (P ≤ 0.05) higher than those in the soil of un-pruned tea bushes. Analysis of phospholipid fatty acids (PLFA) revealed that the rhizosphere of pruned tea plants had higher population of Gram (+) and Gram (-) bacteria, fungi, actinomycetes and lower denitrifying bacterial population as compared to un-pruned tea plants. Activity of acid phosphatase enzyme in soil was also increased due to pruning. A separate study revealed that de-centering may induce production of up to 50% more labile organic carbon compounds by young tea as compared to un-pruned plants. Therefore, it could be concluded that pruned tea bushes secrete more root exudates to influence microbiological and biochemical properties in rhizosphere.     

Generation of interspecific hybrids between <Emphasis Type="Italic">Trifolium vesiculosum</Emphasis> and <Emphasis Type="Italic">T. alexandrinum</Emphasis> using embryo rescue

Interspecific hybrids were developed between Trifolium alexandrinum cultivar Wardan × Trifolium vesiculosum and T. alexandrinum cultivar BL1 × T. vesiculosum through embryo rescue, as the crosses failed to set seed under natural conditions. Trifolium vesiculosum was used as a donor/male parent in this study as it is reported to possess tolerance to stem rot and high forage yield. Fertilization in crossed florets of the crosses was manifested from the recovery of swollen ovaries (< 7.80%) and confirmed from the presence of one degenerated ovule in most (> 93.00%) of the swollen ovaries. The hybrid embryos at various developmental stages (heart, torpedo and cotyledonary) were rescued at a frequency of 2.56% from Wardan × T. vesiculosum and 6.12% from BL1 × T. vesiculosum. Differentiation occurred only in the cotyledonary stage embryos, resulting in 17 putative interspecific hybrid plantlets. The assessment of plantlet hybridity through SSR markers (for the alleles inherited from the donor parent), micromorphological leaf traits (leaf texture and stomata) and morphological characters (plant height, leaflet length and width) confirmed production of two interspecific hybrids designated as AV1 and BV3 representing both the crosses. AV1 displayed moderate resistance and BV3 was resistant to stem rot.     

Arbuscular mycorrhizae in micropropagation systems and their potential applications

Over the past few years, micropropagation techniques are being widely used as an important and advantageous tool for rapid propagation of several commercially important varieties of horticultural and forest tree species. Although, this technology has got several successful applications, low survival rates and poor growth while shifting these plantlets to field conditions are the most common problems which hinders its usage for commercial plant production practices. Inoculation of arbuscular mycorrhizal fungi (AMF) to the roots of micropropagated plantlets plays a beneficial role on their post-transplanting performance. This review discusses the multiple roles played by AMF in the establishment of micropropagated plantlets. Different techniques of mycorrhization and the constraints pertaining to the use of these techniques are also discussed.     

Iron status and growth of rats fed different dietary iron sources

The present study was carried out to investigate the availability of iron from spirulina, whole wheat, whole egg and standard ferrous sulphate in terms of haemoglobin formation, serum and tissue iron levels. Male albino Wistar rats were first depleted of iron by giving low-iron diet (9 ppm) and bleeding 1–2 ml blood at weekly intervals for a period of 21 days. The anaemic rats were repleted with iron sources at a level of 35 ppm for 21 days. Rats receiving whole egg gained significantly (p<0.01) higher weight than the rest of the three groups. The increase in haemoglobin was significantly higher with ferrous sulphate than with whole wheat (p<0.05), spirulina and whole egg (p<0.01). Feeding of ferrous sulphate, whole egg and spirulina produced significantly higher tissue iron levels than feeding of whole wheat. Thus, availability of iron from spirulina and whole egg were found to be comparable to that of the standard.