• No results found





4.4.1 Development of Natural and Synthetic Agrochemicals and their Adjuvants Botanical pesticides

Isolation and characterization of bioactive glucosinolates in leaves and seeds of Brassica juncea.

Glucosinolates, namely, 2-propenyl glucosinolate (Sinigrin), 4-pentenyl glucosinolate (Gluconapin), 5- methylsulfonylpentenyl glucosinolate, 8-methylsulfonyloctyl glucosinolate and 4-hydroxy, 3-(apiosyloxy) benzyl glucosinolate from seeds and n-propyl glucosinolate, 2- hydroxy-2-methylpropyl glucosinolate, 3-methylthiopropyl glucosinolate, 4-methyl-thiobutyl glucosinolate, 3- indolylmethyl glucosinolate, 4-methoxy-3-indolylmethyl glucosinolate, 8-methylsulfonyloctyl glucosinolate and 3,4- dihydroxybenzyl glucosinolate from leaves of B. juncea were isolated as intact glucosinolates and analyzed by ESI-Mass spectroscopy in direct infusion mode. GLSs showed moderate antifungal activity against the two phytopathogenic fungi Macrophomina phaseolina and Fusarium oxysporum.

Identification of cyclic dipeptide from Photorabdus luminescens. A cyclic dipeptide or diketopiperazine was isolated for the first time from the entomopathogenic bacterium P. luminscens in liquid culture and identified as the 3-isobutyl-hexahydro-pyrrolo[1,2-a] pyrazine-1,4-dione or cyclo(-Pro-leu), a cyclic peptide on the basis of 1H-NMR and 13C-NMR. The IR spectrum showed the presence of OH group at 3590 cm-1 and amide at 3380 cm-1 and 1670 cm-1. It showed a violet colour reaction with anisaldehyde/

sulphuric acid and turned blue with chlorine/o-anisidine, pointing to a peptide. It showed strong fungicidal activity against agriculturally important fungi, namely, Rhizoctonia bataticola, Sclerotium rolfsii, Pythium apanidermatum, P.

debarynum and R. solani.

Cyclo(-Pro-leu), a cyclic peptide

Minimum inhibitory concentrations (MIC) of cis cyclo (leucyl-prolyl) from P. luminescens against fungi of agricultural importance

Fungus MIC (mg ml-1)

P. Debarynum 12.50

Rhizoctonia bataticola 25.00

Pythium aphanidermatum 25.00

Sclerotium rolfsii 50.00

Rhizoctonia solani 6.25

Rice sheath blight disease management by the use of botanicals through root dip method. Eight essential oils (Tagetes, patchouli, wintergreen, geranium, palmarosa, lemon grass, cedarwood and clove oils), azadirachtin concentrate, bis(n-propyl)disulfide, three plant extracts (Piper betle, chinaberry, and garlic cloves extracts), three aroma chemicals (alpha-terpineol, linalylacetate and alpha- terpinyl acetate) along with standard fungicide Bavistin were tested at two concentrations (0.5% and 1.0%). The rice seedlings were dipped in the above formulations for three hours prior to transplanting. Systemic activated resistance induction of these botanicals was assessed. The per cent infection was calculated, and the results showed that all the

test chemicals caused reduction of the disease incidence.

Bavistin, chinaberry extract, azadirachtin concentrate, garlic bulb extract, clove oil, linalyl acetate and alpha-terpinyl acetate gave 24.2-29.2% control at one per cent test concentration. Considering the long gap between treatment and disease expression as well as dilution of active ingredients due to biomass accumulation, these results are significant and would provide new insights into SAR induction.

4.4.2 New Synthetic Products

Nucleic bases, nucleosides and their derivatives as nitrification inhibitors. Nineteen various nucleic bases, nucleosides and their derivatives were evaluated for nitrification inhibitory activity in a laboratory incubation experiment at 5% and 10% of urea-N applied for a period of 30 days. The nitrification rates (NR) for all the test compounds ranged from 14.9% to 38.4%, 34.7% to 77.4% and 69.0% to 95.9% nitrification inhibition after 10, 20 and 30 days, respectively. Uracil, 5-Flourouracil, and cytosine showed significantly lower NRs and emerged as promising compounds.

Evaluation of hydrogel performance under rainfed conditions. A pilot experiment was conducted to explore the feasibility of hydrogel use in maize crop under rainfed conditions. An increase in the rate of germination and establishment, plant growth and per cent survival was observed when hydrogel was applied along with the seed at the time of sowing @ 5 kg ha-1. The use of Pusa hydrogel coupled with aqua-ferti technique led to significant enhancement in crop yield as compared to those of control, hydrogel alone and aquaferti alone.

4.4.3 Pesticides: Risk Assessment, Environmental Fate and Remedies Supervised field trials for pesticide risk assessment

Persistence and risk assessment of imidacloprid on onion and tomato. A field experiment was conducted to study persistence and risk assessment of imidacloprid on onion and tomato when sprayed @ 20 g a.i. ha-1 and 40 g a.i. ha-1 for both the crops/trials. Residues of imidacloprid reached non detectable level in 7-10 days in tomato after the treatments, whereas no residues were detected at harvest in onion samples.

The 4x dose of 80 g a.i. ha-1 of imidacloprid did not exhibit any phytotoxic symptom on both the crops and plant compatibility was good. A waiting period of three days is suggested for tomato crop, and seven days for green onion.

Risk assessment of thiacloprid on okra. The residence time of thiacloprid was evaluated on okra fruits and its seeds and soil under the crop when sprayed @48 g a.i. ha-1and 96 g a.i. ha-1. The thiacloprid residues dissipated at a faster rate during the initial stage compared to that in the later period. However,

Effect of nucleic bases, nucleosides and their derivatives on the per cent nitrification inhibition

Compounds Dose Nitrification rate (%)

(%) Period of incubation (days)

10 20 30

5-Flourouracil 5 14.9 36.2 76.6

Uracil 5 16.4 50.3 69.4

Cytosine 5 20.5 40.0 72.2

DCD 5 20.1 40.3 76.5

Urea (alone) - 59.1 90.6 97.7

CD (5%) 4.4 4.6 3.4

Note: Urea-N applied to all the treatments @ 200 ppm

Field evaluation of s-benzylisothiouronium (SBT) salts. A study was conducted to assess the effect of the two most promising SBT salts, namely, SBT butanotate and SBT furoate (identified during lab studies) on the yield of the wheat variety UP 2338 (N: 120 kg N/ha in three splits;

inhibitor dose: 10% of urea N). Both the compounds were found to be superior to urea alone treatment and were on a par with the reference inhibitor, dicyandiamide (DCD) under both conventional and zero tillage systems. The compounds were also found effective in the reduction of nitrous oxide emissions.

Effect of SBT salts on grain yield of wheat

residues were short lived and attained the below detectable level around 10th day. The theoretical maximum residue contribution values were lower, (i.e., 0.081 - 0.151 mg person-1 day-1) than the maximum allowable concentration of 0.5 mg person-1 day-1. Okra seeds and soil collected at the final harvest of the crop did not show the presence of thiacloprid residues.

Persistence of spinosad on brinjal, cauliflower and okra.

Supervised field trials were undertaken to study the persistence of spinosad on brinjal (variety Pusa Kranti ), cauliflower (variety Snowball 16) and okra (variety Pusa A 4) following spray treatment with spinosad (Tracer 45. 5%) @ 75 g a.i. ha-1 and 150 g a.i. ha-1 at flowering/fruiting stage. The residues persisted till day 7 in brinjal fruits as well as on cauliflower curd and okra at the recommended dose of application with half-life of 3.76 days. Based on the results, a waiting period of 1 day is suggested for brinjal, 7 days for cauliflower, and 3 days for on okra in the case of spinosad treatment.

Persistence of indoxacarb on pigeonpea. Indoxacarb (Avaunt 14.5 SC) was evaluated for persistence on pigeonpea.

Foliar application of indoxacarb was made @ 75 g a.i. ha-1 and 150 g a.i. ha-1 on pigeonpea (variety Pusa 855) at 50%

pod formation stage. The residues persisted till day 15 in green pods, and were below 0.03 mg kg-1 in harvest grain samples.

Residues were below the detectable limit in harvest grains (< 0.03 mg kg-1). The half-life of dissipation was 2.1 days and 1.0 day at the recommended and double the recommended dose, respectively.

Persistence of bifenthrin on chickpea and pigeonpea.

Persistence of bifenthrin was studied on chickpea (variety Pusa 256) and pigeonpea (variety Pusa 855) following spray treatment

@ 25 g a.i. ha-1 and 50g a.i. ha-1 at 50% pod formation stage. The residues were found below the detectable limit in chickpea and pigeonpea grains (< 0.01 mg kg-1), at harvest. Therefore, the schedule is considered to be safe from the toxicity point of view.

Persistence of fipronil on mustard, okra and gram.

Mustard (variety Pusa Bold) at 50% pod formation stage, okra (variety Pusa A 4) and gram (variety Pusa 362) were sprayed with fipronil (Reagent 5% SC) @ 50 g a.i./ha and 100 g a.i./

ha at flowering/fruiting stage. The residues in mustard persisted till day 10 in green pods and were below the detectable limit in harvest grains (< 0.05 mg kg-1), whereas no residues of fipronil were detected in okra fruits from day 10 onwards. Results revealed that in gram, the residues persisted beyond 5 days at recommended dose with a half life of dissipation of 1.04 days, and at harvest, the grains did not contain any residues. Based on the calculations, a waiting period of 3 days is suggested for mustard, okra and gram. Environmental fate of pesticides

Leaching behavior of bifenthrin in soil. Leaching of bifenthrin was studied in soil column under saturated flow condition. The analysis of soil cores at different depths for the different treatments revealed that as the volume of water added increased, bifenthrin moved to lower depths. Although bifenthrin residues were detected up to 15 cm depth, bifenthrin in most cases remained in the top 0-10 cm (>99%) layer. Even with 240 ml water addition (equivalent rainfall of 19 cm), residues leached only up to 15 cm depth. For all other treatments, bifenthrin residues were detected only up to 10 cm depth. In all the cases, the major amount was found in 0- 5 cm depth (>90%). The leaching data clearly show that bifenthrin is highly immobile in soil.

Sorption of atrazine on flyash. Coal fly ash, a byproduct from lignite fired thermal power stations, is a low cost adsorbent and can be used for clean up of waste water containing pesticides. Atrazine retention capacity on fly ash from its aqueous solution was studied. The sorption of atrazine (1: 50 (w/v) fly ash to water ratio) at concentrations ranging between 2.5 ppm and 10 ppm was performed using batch method. Per cent sorption of atrazine at these concentrations ranged between 98% and 86%. Analysis of the atrazine sorption data using Langmuir equation indicated that atrazine sorption capacity of fly ash was 3333.3 mg/g, but correlation coefficient (r2) value was 0.951. This suggests that atrazine sorption on fly ash is better explained by Freundlich equation because of relatively higher r2 value. Results indicate that atrazine sorption on fly ash is affected by its particle size, especially at higher concentration. Maximum retention capacity was expressed by 150-250 µ fraction followed by >250 µ and <150 µ fraction.

Desorption studies of atrazine indicated that at initial herbicide concentration of 10 ppm, nearly 9% of atrazine was desorbed after three repeated desorptions. The present study indicates that this low cost adsorbent can be used for clean up of atrazine contaminated water.

Effect of biocompost on pesticide persistence in soil. The effect of biocompost (prepared from sugar industry wastes, i.e., press mud and spent wash which are rich in carbon, potassium and other micro nutrients along with micro-biological bacteria and fungi) applied at the rate of 2.5% and 5.0% on degradation of metribuzin-a triazine herbicide, in sandy loam soil from IARI, New Delhi field was studied. Metribuzin was more persistent in flooded condition than in non-flooded moisture regime in bio-compost-unamended soils, and the respective half life values were 41.2 days and 33.4 days. Application of biocompost to soil incubated under non-flooded moisture regime decreased

the degradation rate of metribuzin; therefore, herbicide was more persistent in biocompost-amended soils than in natural soil. Half life values of metribuzin in T-0, T-1 and T-2 treatments under non-flooded moisture regime were 33.4 days, 38.1 days and 42.4 days, respectively. This may be due to higher sorption of metribuzin in biocompost-amended soil which resulted in reduced bioavailability of metribuzin in soil solution.

However, the application of biocompost to soils incubated under flooded moisture regime did not effect metribuzin degradation and the half life values for treatments T-1 and T-2 were 40.1 days and 39.1 days, respectively.

Decontamination of thiacloprid residues. Zero-day contaminated okra fruits, when washed with tap water, dislodged about 47-50% residues of thiacloprid. The corresponding reductions due to washing followed by steaming were around 78-79%. Washing followed by steaming was found to be more efficient than simple washing with water in removing the residues from the contaminated fruits. Analytical methods

HPLC analysis of herbicide mixture (metsulfuron and clodinafop) in soil and wheat. A simple HPLC method was standardized for the simultaneous residue analysis of clodinafop and metsulfuron methyl in soil and wheat grains using an RP-18 column and acetonitrile-water with acidic pH as the mobile phase at a flow rate of 0.5 ml min-1 at 234 nm. Recoveries were in the range of 85-90% with detection limits for clodinafop and metsulfuron methyl as 0.02µg g-1 and 0.1µg g-1, respectively.

4.4.4 Improvement in Safety and Efficacy of Pesticide Formulations Flowable slurry (FS) formulation of azadirachtin-A

Azadirachtin-A was encapsulated in nanosized amphiphilic polymers. By dissolving encapsulated azadirachtin-A in appropriate solvents, flowable slurry (FS) formulation for seed treatment was developed. Onion seed pellets

Pellets of onion seed for improving its vigour, germination and handling, were developed. These were developed with carriers, surfactant and binding agent, as required. The seed was pre-mixed (w/w) with the carriers (w/w) (kaolinite, bentonite, hydroxy ethyl cellulose, carboxy methyl cellulose, vinylpyrrolidone, polyethyl methacrylate), and binding agent (lignosulphonate, gum acacia, guar gum). The pellets were spherical. An average diameter of the pellet in cross-section can be from about 1 mm to about 7 mm.