Debarati Bhaduri

External potassium (K+) application improves salinity tolerance by promoting Na+-exclusion, K+-accumulation and osmotic adjustment in contrasting peanut cultivars

Achieving salt-tolerance is highly desirable in todays agricultural context. Apart from developing salt-tolerant cultivars, possibility lies with management options, which can improve crop yield and have significant impact on crop physiology as well. Thus present study was aimed to evaluate the ameliorative role of potassium (K(+)) in salinity tolerance of peanut. A field experiment was conducted using two differentially salt-responsive cultivars and three levels of salinity treatment (control, 2.0 dS m(-1), 4.0 dS m(-1)) along with two levels (with and without) of potassium fertilizer (0 and 30 kg K2O ha(-1)). Salinity treatment incurred significant changes in overall physiology in two peanut cultivars, though the responses varied between the tolerant and the susceptible one. External K(+) application resulted in improved salinity tolerance in terms of plant water status, biomass produced under stress, osmotic adjustment and better ionic balance. Tolerant cv. GG 2 showed better salt tolerance by excluding Na(+) from uptake and lesser accumulation in leaf tissue and relied more on organic osmolyte for osmotic adjustment. On the contrary, susceptible cv. TG 37A allowed more Na(+) to accumulate in the leaf tissue and relied more on inorganic solute for osmotic adjustment under saline condition, hence showed more susceptibility to salinity stress. Application of K(+) resulted in nullifying the negative effect of salinity stress with slightly better response in the susceptible cultivar (TG 37A). The present study identified Na(+)-exclusion as a key strategy for salt-tolerance in tolerant cv. GG 2 and also showed the ameliorating role of K(+) in salt-tolerance with varying degree of response amongst tolerant and susceptible cultivars.

Enzymatic activities and microbial biomass in peanut field soil as affected by the foliar application of tebuconazole

Field experiments in peanut (Arachis hypogaea L.) soil ecosystem were conducted during the summer seasons (February–June) of the year 2013 and 2014 in black clay soil treated with tebuconazole at field rate (FR), 2-times FR (2FR) and 10-times FR (10FR) as foliar spray to determine the impact of tebuconazole on soil microbial properties and enzymatic activities. Tebuconazole application at FR and 2FR resulted in a short-lived and transitory toxic effect on soil microbial properties and enzymatic activities. The duration of this disturbance was slightly longer at 10FR. Incorporation of tebuconazole in soil resulted in stimulating the soil microbial activity as evidenced by increased ammonification and nitrification rates and increased soil microbial biomass at later stage. However, it was more toxic to soil ergosterol which is the indicator of the presence of viable fungi. Soil enzymatic activities like fluorescein diacetate-hydrolyzing activity, urease, phosphatase and aryl sulfatase are either unaffected or shortly inhibited and then recovered. However, dehydrogenase and nitrate reductase activity decreased more drastically and can be used as valuable indicator to assess the impact of tebuconazole application on soil health. The results indicated that instead of single assays, a broad spectrum analysis of soil microbial and enzymatic activities gives a better insight about the impacts of pesticide on soil health. From this study, it is also concluded that the application of tebuconazole at 10FR had adverse effects on the microbial variables and the effect on long-term application should be studied further.

Behaviour of pendimethalin and oxyfluorfen in peanut field soil: effects on soil biological and biochemical activities

A field experiment was conducted to study the dissipation kinetics of herbicides pendimethalin and oxyfluorfen in black soil of peanut field at half recommended rate (HRE), recommended rate and double recommended rate as well as to assess their effects on soil microbial parameters and enzymatic activities. In addition, their role in the transformations and availability of some plant nutrients like nitrogen transformation (through ammonification and nitrification processes) and availability of phosphorous were also studied. Incorporation of these herbicides was found to stimulate the activity of soil microbial biomass carbon, fluorescein diacetate hydrolysing activity, alkaline phosphatase and ammonification rates, while dehydrogenase activity, acid phosphatase, nitrification rate and available phosphorous was adversely affected. However, urease remains almost unchanged except for little stimulation at later stages. Dissipation of pendimethalin and oxyfluorfen followed first-order reaction kinetics with half-life (T1/2) of 13.7–20.1 and 21.5–27.4 days, respectively. Residues of both herbicides persisted up to 60 days in the soil at all the doses except 45 days for pendimethalin at HRE.

Improvement in Productivity, Water-Use Efficiency, and Soil Nutrient Dynamics of Summer Peanut (Arachis hypogaea L.) through Use of Polythene Mulch, Hydrogel, and Nutrient Management

ABSTRACT Agronomic management through better use of inputs benefits farmers both by enhancing productivity and profitability. A field experiment was conducted in consecutive summer seasons (2011–2013) consisting of two mulching (no mulch, polythene mulch), three hydrogel (0, 2.5, 5.0 kg ha−1), and three nutrient management treatments (organic, inorganic, and integrated) in a split–split plot design. Use of mulching and 2.5 kg hydrogel ha−1 and integrated nutrient management enhanced pod, haulm, kernel and oil yields, and net economic returns. Partial factor productivity and water-use efficiency were higher under polythene mulch and 5.0 kg hydrogel ha−1. Higher nutrient uptakes were obtained under both mulching and integrated nutrient management. Use of 2.5 kg hydrogel ha−1 resulted in more removal of N; P and K uptakes were higher in 5.0 kg hydrogel ha−1. Combination of three managements had a consequence of actual soil N loss, but gains in soil P and K after three cropping cycles.