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Crop Growth Analysis (CGR, RGR, NAR, LAI, LAD)

Source: R/agronomic_analysis.R
crop_growth_analysis.Rd

Classical growth analysis from sequential harvests: crop growth rate, relative growth rate, net assimilation rate, leaf area index and leaf area duration for each interval between samplings.

Usage

crop_growth_analysis(
  dry_weight,
  leaf_area = NULL,
  days,
  verbose = TRUE,
  ground_area = NULL
)

Arguments

dry_weight

Dry matter at each sampling (g per sample).

leaf_area

Leaf area at each sampling (cm2 per sample), or NULL to compute only CGR and RGR.

days

Days after sowing at each sampling (strictly increasing).

verbose

Logical. If TRUE (default), prints the table.

ground_area

Land area occupied by each sample (m2). When given, CGR is expressed in g m-2 day-1 and LAI = leaf area / ground area. When NULL (default), CGR is in g per sample per day and LAI is leaf area / 10000 (that is, leaf area in cm2 per m2 of ground).

Value

A data frame of class aridagri_growth with one row per interval: Period, CGR, RGR and, with leaf area, NAR, LAI_start, LAI_end and LAD.

Details

For two samplings at \(t_1\) and \(t_2\) (Watson, 1952; Radford, 1967):

  • CGR = \((W_2 - W_1) / [P (t_2 - t_1)]\), P = ground area

  • RGR = \((\ln W_2 - \ln W_1) / (t_2 - t_1)\) (g g-1 day-1)

  • NAR = \(\frac{W_2 - W_1}{t_2 - t_1} \times \frac{\ln L_2 - \ln L_1}{L_2 - L_1}\), reported in g m-2 (leaf) day-1

  • LAD = \((LAI_1 + LAI_2)(t_2 - t_1) / 2\) (days)

References

Radford, P.J. (1967). Growth analysis formulae: their use and abuse. Crop Science, 7(3), 171-175. doi:10.2135/cropsci1967.0011183X000700030001x

Watson, D.J. (1952). The physiological basis of variation in yield. Advances in Agronomy, 4, 101-145. doi:10.1016/S0065-2113(08)60307-7

Author

Lalit Kumar Rolaniya, Ram Lal Jat, Monika Punia, Raja Ram Choudhary, Hemant Poonia

Examples

dry_weight <- c(0.5, 2.1, 8.5, 25, 45, 62, 75)
leaf_area <- c(15, 85, 350, 800, 950, 850, 600)
days <- c(15, 30, 45, 60, 75, 90, 105)
crop_growth_analysis(dry_weight, leaf_area, days, ground_area = 0.09)
#> 
#> ======================================================================
#>  CROP GROWTH ANALYSIS
#> ======================================================================
#>      Period    CGR     RGR   NAR LAI_start LAI_end     LAD
#>   15-30 DAS  1.185 0.09567 26.43   0.01667 0.09444  0.8333
#>   30-45 DAS  4.741 0.09321 22.79   0.09444 0.38890  3.6250
#>   45-60 DAS 12.220 0.07192 20.21   0.38890 0.88890  9.5830
#>   60-75 DAS 14.810 0.03919 15.28   0.88890 1.05600 14.5800
#>   75-90 DAS 12.590 0.02136 12.61   1.05600 0.94440 15.0000
#>  90-105 DAS  9.630 0.01269 12.07   0.94440 0.66670 12.0800
#> 
#>  CGR: g m-2 day-1 | RGR: g g-1 day-1 | NAR: g m-2 (leaf) day-1 | LAD: days