Root-knot nematodes (Meloidogyne spp.) pose a significant threat to global agriculture causing substantial yield losses. Talaromyces is a well-known biocontrol fungus used against the root-knot nematodes. To assess the diversity of nematophagous Talaromyces spp. from the rhizospheric soils, we employed a novel technique that used target root-knot nematode as prey to isolate the fungi. A total of 26 Talaromyces isolates belonging to 12 nominal species were identified across varied agroclimatic zones of India. Detailed morphological and molecular characterisation revealed the presence of T. adpressus, T. oumae-annae and T. veerkampii, hitherto unreported from India. Nine Talaromyces spp. found in the present investigation were not known to possess nematophagous ability to date. Nematophagous ability of the isolated fungal species was confirmed through in vitro studies using M. incognita and M. graminicola. The isolate F17 (T. pinophilus) was found to induce 100% mortality of the nematodes. Further, in vivo studies conducted with F17 isolate using M. incognita-tomato and M. graminicola-rice pathosystems showed up to 79.8% and 74.7% reduction in nematode galling, respectively, along with plant growth promotion. Expression of green fluorescent protein in the F17 isolate helped track the progress and nature of juvenile parasitism. The GC-MS profiling of volatile organic compounds in F17 revealed the presence of 32 bioactive components that reportedly contain nematicidal potential, thus corroborating the in vitro mortality. The performance of the fungal isolate F17 (T. pinophilus) inculcates high confidence to propose it as a prospective bioagent to be commercially developed for root-knot nematode management.
Although growing in popularity in developed countries, organic kiwifruit (Actinidia deliciosa) production still has several operational challenges, including limited availability of organically approved growth regulators, nutrient inputs and insecticides. In this study, 11 biostimulant treatments were tested, including T1: Water spray (control), T2: 5% KA sap (Kappaphycus alvarezii), T3: 10% KA sap, T4: 5% GE sap (Gracilaria edulis), T5: 10% GE sap, T6: 5% AN sap (Ascophyllum nodosum), T7: 10% AN sap, T8: 5% Vermiwash, T9: 10% Vermiwash, T10: 5% Humic acid and T11: 10% Humic acid. The biostimulants were used as root zone soil applications four times per year: 1) before flower bud opening, 2) at 1 month after fruit set, 3) at 3 months after fruit set, and finally 4) at 5 months after fruit set. In terms of growth attributes of the kiwifruit cultivars Allison and Hayward, treatment T2: 5% KA sap showed the best results for sprouting percentage and yield per vine, while treatment T8: 5% Vermiwash exhibited the best results for fruitful bud percentage, fruit shoot-1 and grade-A fruit percentage. The majority of the quality traits were found to be significantly higher with the application of treatment T2: 5% KA sap, compared with the control. DPPH and ABTS assays showed maximum values with T8: 5% Vermiwash and T10: 5% Humic acid, respectively. It was concluded that the application of biostimulants like seaweed extracts, vermiwash and humic acids can be used to increase the quality, yield and production economics of organic kiwifruit production.
The Himalayan foothills experience heavy rainfall and imbalanced fertilization, particularly with potassium (K). In traditional farming, K fertilization is often low or neglected, resulting in a decline in crop productivity. This study aims to evaluate the impact of bio-cover addition, tillage, and bioinoculants on wheat yield, K availability, and quantity-intensity relations in the Himalayan foothills of India. A field experiment was conducted in a factorial randomized block design with three replications, comprising eight treatment combinations: zero tillage or conventional tillage, no or bio-cover addition and no or seed treatment using bioinoculants in the rice-wheat system. Soil samples were collected from post-wheat plots. The results showed that following zero tillage and bio-inoculation, wheat yields increased by 4% and 11%, respectively. Bio-cover addition with bio-inoculation and tillage with bio-inoculation also increased the yield. However, the three-way interaction of these practices did not notably vary the yield. Among fractions of K, water-soluble K increased in bio-cover addition and decreased in zero tillage practice. Additionally, bioinoculants did not affect this fraction of K. Exchangeable K was higher when combining zero tillage with bio-cover and bioinoculants, whereas non-exchangeable K did not vary with tillage practices and bioinoculants; moreover, bio-cover additions improved this fraction of K. In the case of mineral K and total K, zero tillage and bio-cover addition increased in the soil, except in the deeper layer. Among quantity/intensity parameters, potential buffering capacity was significantly highest when combining zero tillage with bio-cover and bioinoculants, contrasting with the activity ratio, which was highest when combining conventional tillage with bio-cover and no bioinoculants. The correlation study showed that the fractions of K and quantity/intensity parameters were in dynamic equilibrium. Therefore, this study concludes that management practices such as zero tillage, bio-cover addition, and bioinoculants in the Himalayan foothills of India can enhance K availability in the soil. Overall, we recommend that long-term bio-cover additions under zero or conventional tillage with bio-inoculations can improve and maintain K supply in the rice-wheat system.
In the northeastern sub-Himalayan terai region of India Citrus limon (L.) Brum F. is found to be endemic and usually propagated through stem cuttings. The plants generated from stem cutting require one year or more of orchard establishment. There are two reasons for this long nursery period. Firstly, the extensively lignified stem of C. limon delays the process of root induction. Secondly, the small marginal farmers of this region can’t afford the root-inducing hormones like indole butyric acid (IBA). In this regard, indigenous bacteria that produce diffusible phytohormones, indole acetic acid, can be exploited to quicken the process of root induction from the stem cuttings. In this study, three seed-protective microbes, namely, Priestia, Pseudomonas, and Bacillus sp., were screened for their exopolysaccharide (EPS)-producing ability. This ability was essential for a stronger attachment to the stem cuttings. Secondly, the production of indole acetic acid (IAA) was also monitored. Though Bacillus sp. increases its EPS, its IAA production drops at lower temperatures. The Pseudomonas sp. enhanced its IAA production at a lower temperature. All the strains improved the rooting process of C. limon within 180 days. However, the Pseudomonas sp. displayed a significantly higher root induction. This was due to the non-sporulating nature of Pseudomonas sp. As a spore is a dormant structure that cannot produce EPS or IAA, the relative amount of metabolically active cells is lower. Thus, such bacteria can reduce the time for the nursery phase from 365 days to 180 days.
Iron (Fe2+) toxicity is more prevalent in lowland rice ecosystems, where it negatively affecting rice growth and causing substantial yield losses. This yield loss causing Fe2+ toxicity has to be addressed using cost-effective farm-based materials and agronomic practices. This study therefore evaluated rice husk (RHB) and bamboo biochar (BB) as adsorbent for Fe2+ removal from aqueous solution via adsorption experiment. Subsequently, their efficacy in alleviating Fe2+ toxicity in rice cultivated under two contrasting moisture regimes (continuously waterlogged (CW-MR) and continuously saturated moisture regime (CS-MR)) was evaluated through pot experiment. The maximum adsorption capacity of RHB and BB was 2.23 and 1.36 mg g− 1, respectively. The Fe2+ adsorption on RHB and BB was well fitted by Langmuir and Freundlich isotherm (R2 > 0.96), respectively. In pot experiment, application of 5
