Synthetic Insecticides, Fungicides, Nematicid

• Variance Definition: In agricultural statistics and biometrics, variance (denoted by $\sigma^2$ for population or $s^2$ for sample) is the mean of the squared deviations of individual observations from their arithmetic mean.
• Relationship with Standard Deviation: Standard deviation is the positive square root of variance ($\text{SD} = \sqrt{\text{Variance}}$), which means variance is mathematically the square of the standard deviation ($\text{Variance} = \text{SD}^2$). (Correct answer: Option 2)

• Calculation of Unknown Concentration via GC Linear Calibration:
• In Gas Chromatography with a linear detector response:

• Given:
• $C_{\text{standard}} = 10\text{ ppm} = 10\text{ mg/L}$
• $\text{Area}_{\text{standard}} = 121,380$
• $\text{Area}_{\text{unknown}} = 8,092$
• Calculation:

• Conclusion: The concentration is $0.67\text{ mg/L}$ (Option 2).

Correct option: (2) 0.67 mg L*

• Latin Square Design (LSD): A single-factor experimental design where a single set of treatments is arranged in a square grid to eliminate two perpendicular sources of extraneous soil heterogeneity (row blocking and column blocking simultaneously). (Correct answer: Option 3)
• Factorial RCBD: Multi-factor design studying two or more factors and their interaction effects.
• Split-plot Design: Multi-factor design where main-plot factors require large operational plots and sub-plot factors require smaller precision plots.
• Strip-plot (Split-block) Design: Two-factor design where both factors require large contiguous strips perpendicular to each other.

• DRIS (Diagnosis and Recommendation Integrated System): Developed by E.R. Beaufils in 1973 for sugarcane and later calibrated across various field and orchard crops.
• Methodology: Evaluates plant nutritional status by comparing nutrient elemental ratios (e.g., N/P, N/K, P/K) with calibrated standard norms derived from high-yielding populations, minimizing dilution and concentration effects caused by plant age or dry matter accumulation. (Correct answer: Option 3)
• Olsen: Developed the sodium bicarbonate method for available phosphorus extraction in alkaline soils.
• Liebig: Formulated the Law of the Minimum (1840).
• Arnon: Formulated the Criteria of Essentiality of plant nutrients with Stout (1939).