A humic acid improves growth of tomato seedling in solution culture

The effects of humic acid (HA) on nutrient accumulation and growth of tomato seedlings were evaluated in a solution of limited nutrient availability in a greenhouse. HA additions were made to the nutrient solution at rates of 0, 640, 1280, or 2560 mg/L. The addition of 1280 mg/L HA produced significant increases in shoot accumulation of P, K, Ca, Mg, Fe, Mn, and Zn as well as increased accumulation of N, Ca, Fe, Zn, and Cu in roots. Fresh and dry weights of roots were also increased, However, on comparing nutrient accumulation in plants treated with 1280 mg/L HA and those given an additional supply of nutrients equivalent to those supplied by HA at the 1280 mg/L rate, shoots accumulated more N, P, K, Fe, and Cu, while roots accumulated more K and Ca. Therefore these increases do not appear to be associated with nutrients contained in HA. Eectrolyte leakage, as an indication of membrane permeability, did not differ as a consequence of HA additions. However, electrolyte leakage correlated positively with HA rate. A shift in solution pH from 5.8 to 7.0 had no effect upon on nutrient accumulation or growth of tomato seedlings. The interaction of pH and addition of HA was not significant. [1]

Effect of Trichoderma isolates on tomato seedling growth response and nutrient uptake

Trichoderma species are commonly used as biological control agents against phytopathogenic fungi and some isolates are able to improve plant growth. In this study, the effects of three Trichoderma isolates including Trichoderma harzianum isolate T969, T. harzianum isolate T447 and Trichoderma sp. isolate T in tomato seedling vigor and their nutrient uptake via two inoculants introduction methods (inoculating seed with Trichoderma spore suspension and inoculating nursery soil with Trichoderma fortified wheat) were examined. Seed germination rate was not affected by Trichoderma application, but shoot height, shoot diameter, shoot fresh and dry weight and root fresh and dry weight in tomato seedlings were interestingly (p ≤ 0.05) increased when sown in Trichoderma sp. T and T. harzianum T969 fortified soil and when compared to the control. The soil amended by Trichoderma sp. T and T. harzianum T969 had marked increase in leaf number and leaf area (p ≤ 0.05). Chlorophyll content increased in seedling grown in Trichoderma sp. T amended soil as well as in Trichoderma sp. T and T. harzianum T969 coated seed. A dramatic increase (p ≤ 0.05) in the concentrations of Ca2+, Mg2+, P and K+ were recorded in the seedling shoot and root among T. harzianum T447 soil amended treatment when compared to the control, except for Na+ level in soil amendment with T. harzianum T969 and seedcoating with strain Trichoderma sp. T, which significantly reduced the Na+ concentration. [2]


Biochar soil amendment increases tomato seedling resistance to drought in sandy soils

Expanding aridity threatens agriculture in much of the world. Small farms (less than two hectares) produce 90% of the food in Eastern and Southern Africa and provide 70% of employment for women in the Least Developed Countries. Aridity thus endangers both food production and the employment of women. One possible solution is the addition of biochar, a highly porous pryrolysed biomass which is well documented to help retain water and nutrients in soils. Most current literature, however, proposes quantities of biochar which are beyond reach of small farms. The purpose of this research was thus to develop a method which would allow small amounts of biochar to provide significant protection for plants in their most vulnerable stage, the seedling. The test species was the cultivated tomato (Lycopersicon esculentum) because this is an important crop for subsistence farmers, and the seedlings are highly susceptible to drought. The results demonstrate that, in sandy substrates, 30% (v/v) biochar, concentrated in seedling root zones, significantly increases seedling resistance to wilting. Normal cooking can produce about 500 g of biochar a day and thus make possible increased wilting resistance for over 4000 tomato seedlings each year. This benefit is therefore within the reach of a demographic whose success is critically important to global sustainability. [3]

Effect of Biological Control Antagonists Adsorbed on Chitosan Immobilized Silica Nanocomposite on Ralstonia solanacearum and Growth of Tomato Seedlings

Background: Biological control holds promise in managing bacterial wilt disease. However, its efficacy is limited by harsh environmental conditions when applied without use of suitable carrier materials.

Aim: The study entailed synthesis of nanocarrier materials for biological control agents (BCAs) using Chitosan and silica nanocomposites.

Site and Duration: The experiments were carried out at Jomo Kenyatta University of Agriculture and Technology for a period of two years June 2013 to June 2015.

Methodology: The experiments were conducted using a completely randomized design with three replications. Deacetylation, functionalization and immobilization of chitin on mesoporous silica nanoparticles (MSN) to form chitosan immobilized silica nanocomposites (CISNC) gel was done.

Results: This resulted in formation of chitosan nanoparticles and CISNC with crystallite sizes of 2.8 and 4.4 nm respectively. BCAs were adsorbed on CISNC gel. Characterization of the bio-nanocomposites showed that they had physisorption properties thus, ideal carriers for BCAs. CISNC gel had the highest significant (P=.05) sorption properties with 75% and 65% adsorption and desorption respectively of BCAs. Efficacy trials were done by in vitro pathogen inhibition and greenhouse bioassays using tomato seedlings. Adsorption of BCAs on CISNC gel significantly (P=.05) increased inhibition efficacy of BCAs on R. solanacearum from 50 to 70%. This was attributed to the antibacterial effect of the individual substances and the overall synergy acquired. Further, BCA-CISNC gel forms a film around root hairs, initiates fast wound healing mechanism and induce prophylactic effect on tomato seedlings challenged with R. solanacearum pathogen, decreasing wilting incidences from 45 to 25%. Additionally, BCA-CISNC complex significantly (P=.05) increased tomato seed germination from 70 to 80% and growth rate from 12 to 15% due to enhanced water utilization efficiency, induced phytohormones and nutritional benefit. BCAs also aided faster nutrient release, absorption and utilization by tomato plants.

Conclusion: Therefore, adsorption of bacterial, fungal and phage biocontrol agents on CISNC gel, a complex hitherto not reported to have been used in R. solanacearum disease control, enhanced microbial efficacy against the pathogen and increased tomato productivity. [4]

Alternative Substrates for Production of Cherry Tomato Seedlings

The cherry tomato crop has a high production cost, which can be reduced in part using alternative substrates. The objective of this study was to evaluate the different alternative substrates for production of cherry tomato seedlings. The experiment was performed in a completely randomized design with five treatments (T1: Bioplant® commercial substrate (control treatment); T2: Earthworm humus; T3: Soil; T4: Mixture of 50% soil + 50% earthworm humus; T5: Mixture of 75% soil + 25% earthworm humus) in four replicates. Seedlings were collected and evaluated at 28 days after sowing. There was significant effect of the substrates in relation to the traits plant height, leaf number, fresh matter of aerial part and dry matter of aerial part. Based on the dry matter of aerial part, the treatments T1, T2, T4, and T5 presented the best plant development due to the accumulation of photoassimilates. Most of the alternative substrates had similar behavior to the commercial substrate, being reflected in the plant vigor and yield. Finally, we concluded that there are alternative substrates capable of replacing the commercial substrate. The T5 treatment is the most indicated, since it did not differ from the commercial substrate in relation to the agronomic traits and presented a production cost of only 24% in relation to the commercial substrate cost. [5]

Reference

[1] David, P.P., Nelson, P.V. and Sanders, D.C., 1994. A humic acid improves growth of tomato seedling in solution culture. Journal of plant nutrition, 17(1), pp.173-184.

[2] Azarmi, R., Hajieghrari, B. and Giglou, A., 2011. Effect of Trichoderma isolates on tomato seedling growth response and nutrient uptake. African Journal of Biotechnology, 10(31), pp.5850-5855.

[3] Mulcahy, D.N., Mulcahy, D.L. and Dietz, D., 2013. Biochar soil amendment increases tomato seedling resistance to drought in sandy soils. Journal of arid environments, 88, pp.222-225.

[4] Dennis, G., Harrison, W., Agnes, K. and Erastus, G. (2016) “Effect of Biological Control Antagonists Adsorbed on Chitosan Immobilized Silica Nanocomposite on Ralstonia solanacearum and Growth of Tomato Seedlings”, Advances in Research, 6(3), pp. 1-23. doi: 10.9734/AIR/2016/22742.

[5] Silva, J. da, Teixeira, J. dos S., Silva, M. T. da, Santos, D. F. dos, Júnior, A. B. da, Carvalho, A. P. V. de and Costa, K. D. . (2017) “Alternative Substrates for Production of Cherry Tomato Seedlings”, Journal of Experimental Agriculture International, 18(4), pp. 1-7. doi: 10.9734/JEAI/2017/36984.

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