The use of controlled release fertilizer (CRF) has become a new trend to minimize environmental pollution. In this study, urea-kaolinite containing 20 wt% urea after one hour dry grinding was mixed with different concentrations of chitosan as a binder to prepare nitrogen-based CRF. Fourier transform infrared spectroscopy confirmed the hydrogen bonding between urea and kaolinite. Covalent interaction between urea-kaolinite and chitosan make the granules stronger. The nitrogen release was measured in 5 days interval using a diacetylmonoxime calorimetric method at a wavelength of 527 nm. The results illustrated that by increasing the chitosan concentration from 3 to 7.5%, nitrogen release decreased from 41.23 to 25.25% after one day and from 77.31 to 59.27% after 30 days incubation in water. Compressive stress at break tests confirmed that granules with chitosan 6% had the highest resistance and were chosen for ammonia volatilization tests. Ammonia volatilization was carried out using the forced-draft technique for a period of 10 weeks. The results showed that the total amount of ammonia loss for conventional urea fertilizer and urea-kaolinite-chitosan granules was 68.63 and 56.75%, respectively. This controlled release product could be applied in agricultural crop production purpose due to its controlled solubility in the soil, high nutrient use efficiency and potential economic benefits.
Implementation of sound fertilizer management in rice cultivation is essential in optimizing productivity and profitability. The use of controlled release fertilizer (CRF) to improve crop production in various cropping systems has been widely explored, with new approaches and materials continually being studied to produce new CRF. A field study was carried out to determine the efficiency of local CRFs on rice production and N uptake using MR220 CL1 rice variety. Ten different types of CRFs consisting of two groups namely biochar impregnated urea (
Urea-intercalated kaolinite containing 20 wt% urea was granulated and coated with water-based epoxy resin to prepare nitrogen-based controlled release fertiliser (NCRF). The nitrogen release property was studied using UV-Vis spectroscopy through the diacetylmonoxim colorimetric method for different samples of granules of urea-intercalated kaolinite and nonintercalated urea-kaolinite mixture. Also the effect of granules size and different coating thickness on nitrogen release from coated NCRFs was investigated. The results of release experiments revealed that intercalation of urea into kaolinite caused a three times decrease in the nitrogen release compared to non-intercalated sample. Also, by increasing the size of granules and thickness of coating, the nitrogen release ratio from NCRFs decreased. Finally, a glasshouse trial was conducted to evaluate the effect of coated urea-kaolinite compared with a non-coated one and conventional urea fertiliser granules on rice productivity (Variety MR 219). The yield together with some yield component data (filled spikelet, spikelet per panicle, productive tiller) revealed a highly significant and positive response to coated CRF N fertiliser treatment (one time application). Also, the pooled data of the yield and yield component emphasised that the rice crop responded significantly to treatments involving CRF nitrogen fertilisers as compared to others. The maximum grain yield of 28.73 g/pot belongs to coated CRF, medium grain yield of around 21.74 g/pot from the non-CRF N fertilisers plots and the lowest yield was obtained where conventional urea was applied. The other morphological and physiological characters show a similar trend to the yield.
The complexity and polygenic nature of the salt tolerance trait in plants needs to develop a multiple indicator in the screening process. The mentioned issue led us to carry out an experiment to identify tolerant genotypes through multiple parameters in Andrographis paniculata. For this purpose, the 40-days seedlings were grown in different salinity levels (control, 4, 8, 12 and 16 dS m−1) on Hoagland's medium. The results indicated that salinity had a significant effect on the morphological, physiological and biochemical traits. All measured morphological traits, and chlorophyll, K+ and Ca2+ content were significantly decreased with increasing salinity levels, while proline and Na+ content increased. The present exploration revealed that, salt tolerance index (STI), using the multiple regression model, demonstrated a more stable trend than the single variable assay (total dry weight). Furthermore, STI based on multiple regression analysis gives an accurate definition of salttolerant individuals. Under salt stress, tolerant accessions had high STI and produced higher proline, K+ and Ca2+, and lower Na+ content than sensitive accessions. Cluster analysis based on related traits to STI, indicated high similarity in each group. These outcomes can be utilized to evaluate the salt tolerance threshold in the species and may have a great advantage over conventional methods. Probably, our upshots can be applied in the next breeding programs to develop salt-tolerant varieties.
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