The effect of nitrogen source and quantity on disease expression of Neonectria ditissima in apple

The effects of nitrogen on the interaction between apple trees and European canker caused by Neonectria ditissima are not well understood. Previous field and laboratory studies have shown that nitrogen affects N. ditissima disease development, germination and germ-tube growth in vitro but the type of nitrogen source has not been examined in vivo. Therefore, the aim of this study was to determine the effects of root-applied nitrogen from different sources on the development of European canker on inoculated potted trees. One-year-old ‘Royal Gala’ trees were planted in a low-nitrogen growth substrate and treated with a range of concentrations of calcium ammonium nitrate (CAN) or other nitrogen sources (Ca(NO3)2, KNO3, (NH4)2SO4, NH4NO3, urea, YaraMila™) at equivalent molar rates of nitrogen as the highest CAN treatment. Treatments were applied during the growing season (Nov to May). The control treatment received no applied nitrogen. Bud and leaf scar wounds were inoculated at leaf fall with N. ditissima conidia. Tree growth and health, disease progression and leaf nitrogen content were monitored. The rate of nitrogen application affected tree diameter and leaf nitrogen content while the nitrogen source mainly affected tree survival, powdery mildew incidence, leaf weights, leaf nitrogen and European canker symptom expression. Trees treated with (NH4)2SO4 had the lowest survival rates and highest leaf nitrogen content. Disease expression was highest with NH4NO3 and lowest with KNO3 applications. The control plants (which received no additional nitrogen), showed the least amount of both growth and disease expression. Applications of CAN, even at the lowest rate (20 g), increased disease susceptibility. Increasing rates of CAN applications did not significantly increase disease incidence. Nitrogen concentration is an important factor in the disease development of European canker of apple. Field evaluation is recommended to further validate these results.

Influence of Nitrogen Fertilization on Root Growth Dynamics and Yield of Chia (Salvia hispanica L.) in Greenhouse Pots

A greenhouse pot experiment was conducted in Western Greece in order to evaluate the effect of different nitrogen rates on the development of the root system and productivity of chia (Salvia hispanica L.) plant. The experiment followed a completely randomized design (CRD), with six treatments, different rates of applied nitrogen (0, 25, 50, 75, 100 and 125 kg ha-1 equivalent to 0, 134, 268, 402, 536 and 670 mg nitrogen pot-1). The results of this study showed that root length density (RLD) and root mass density (RMD) increased with the increased rate of applied nitrogen and the highest values (1.297 cm cm-3 and 1.178 mg cm-3, respectively) were found after the application of 670 mg nitrogen pot-1 at 100 days after sowing (DAS). Plant height (106.06 cm) and leaf area per plant (883.14 cm2) were significantly affected by the highest rate of nitrogen. Additionally, dry matter and seed yield per plant were clearly affected by fertilization, with the highest values (27.57 g and 4.20 g, respectively) obtained in plants treated with 670 mg nitrogen pot-1. In conclusion, increasing the levels of applied nitrogen up to 670 mg N pot-1 improves root development and therefore the yields of chia.

Effect of biopreparations on the decomposition of plant residues of crops in typical chernozem

Aim. To identify the effect of biological preparations applied with or without nitrogen fertilizers for crop by-product, their incorporation into the soil on the decomposition of plant residues and composition of mobile humus substances in typical slightly eroded chernozem.Materials and Methods. The study was carried out in the field experimental station of Kursk FARC in the cycles of cereal and cereal-row crop rotations in variants with by-product treated with biopreparations; with applied biopreparations + nitrogen fertilizers; with applied nitrogen fertilizers and without biopreparations. To study decomposition the content of unhumified organic matter was determined in the topsoil by the monolith method after by-product incorporation into the soil and 3045 days after their decomposition. Simultaneously the composition of mobile humus substances in the soil was determined.Results. The decomposition of crop by-product and after harvesting and root residues mixed with it in the soil and treated with biopreparations or nitrogen mineral fertilizers was studied for the first time. The peculiarities of the effect of the factors studied on the degree of plant residue decomposition and the composition of mobile humus substances were shown.Conclusion. It was determined that treating the by-product of barley, buckwheat and sunflower with bioproducts, both with applied nitrogen fertilizers and without them, contributed to the increase in the degree of plant residue decomposition as compared with the control and nitrogen mineral fertilizer application. In the years which are favourable according to hydrothermal conditions the improved quality of mobile humus substances of the soil influenced by biopreparations are noted and under extreme conditions the tendency to the improvement of their quality is observed.

The effects of clover and nitrogen fertiliser on the presence of pasture pests in dairy pastures

A comprehensive dataset obtained from sampling four trials investigating interactions between perennial ryegrass and white clover under two levels of applied nitrogen (N) has highlighted different effects of pasture composition and N use on pasture pests.• For swards with white clover, presence of clover root weevil, whitefringed weevil and grass grub increased under low N by 36%, 11% and 5%, respectively, compared with high N treatments.• High N increased the presence of both Argentine stem weevil and root aphid by 7%.• Unexpectedly, clover reduced the presence of two grass feeders, Argentine stem weevil and black beetle, by 7% and 11% respectively.• Presence of grass grub was 17-30% lower under tetraploid ryegrasses than under diploids.• More clover and reduced N fertiliser inputs could reduce the frequency of black beetle and Argentine stem weevil with environmental benefits.

Nitrogen Transformation in Waterlogged Soil in Indian Rice Fields: A Review

No other element can match the essentiality of nitrogen in soil for growth and development of plants and its transformations among various forms viz., nitrite, nitrate, ammonium are mostly mediated by microbes. As its transformation depends on major microbial activity and thus, there is a huge difference between the transformation of it in aerobic soil and anaerobic soil. This difference mainly arises due to presence and absence of oxygen. The absence of oxygen in soil creates anaerobic condition and thus promotes the growth of anaerobic microbes. In submerged soil, applied nitrogen is lost in various forms such as volatilization, denitrification, leaching and runoff out of which ammonium volatilization causes the maximum loss. The recovery of applied nitrogen, as recorded from various filed experiments in India, has been found to vary from 28 to 34% for submerged rice. The chemistry of nitrogen in submerged soil is quite interesting for this review.

REACTION OF RICE VARIETIES PERMITED FOR USE IN CONNECTION WITH YIELD FORMATION WITH A HIGH GRAIN QUALITY ON LEVEL OF NITROGEN NUTRITION IN AGROLANDSCAPE ZONES OF KRASNODAR REGION

An increase in the doses of nitrogen fertilizers applied during the cultivation of new rice varieties Nautilus and Yakhont in the old-deltoid and valley agrolandscape zones led to significant changes in grain quality traits. The grain size of the varieties grown in the Krasnoarsmeysky district did not change due to the level of nitrogen fertilizers, for those grown in the Abinsky district, decreased by 0.3 g in variety Nautilus and increased in variety Yakhont with increased dose of applied nitrogen. The vitreousity of grain increased in Nautilus in the Krasnoarmeysky district by 2%, in Abinsky - by 7%; in the variety Yakhont - increased by 2% and practically did not change, respectively. A tendency toward a decrease in grain fracture in the Krasnoarmeysky district and an increase in head rice content in the variety Nautilus in the Krasnoarmeysky and Abinsky districts was noted.