TABLE 2.
Segregation and shortlisting of phenotypic parameters for N-response, yield and NUE: The % effect of normal N over low N on each of the 25 parameters was calculated using the mean values of 32 replicates and combined for all the genotypes.
| S. No. | N-responsive parameters | Low N-responsive yield related parameters | N- use efficiency parameters |
| 1 | (a,b,c) Germination (G) | (a,b,c) Germination (G) | (a,b,c)Germination (G) |
| 2 | (a,c) Chlorophyll (V1) | (a,b,c) Shoot length before harvest (V7) | (a,b,c)Shoot length before harvest (V7) |
| 3 | (a,b,c) Green leaf number at vegetative stage(V2) | (a) Total leaf number at flowering (V8) | (a,b,c)Fresh biomass (V11) |
| 4 | (b,c) Yellow leaf number at vegetative stage (V3) | (a,b,c)Fresh biomass (V11) | (a,b,c)Shoot length after harvest (V12) |
| 5 | (a,b,c)Total leaf number at vegetative stage (V4) | (a,b,c)Shoot length after harvest (V12) | (a,c)Root length(V13) |
| 6 | (a,b,c)Leaf width(V5) | (a,b,c)Root length(V13) | (a,b,c)Total plant height (V14) |
| 7 | (a,b,c)Stem thickness (V6) | (a,b,c)Total plant height (V14) | (a,b,c) Dry biomass (V15) |
| 8 | (a,b,c)Shoot length before harvest (V7) | (a,b,c)Dry biomass (V15) | (a,c)Flowering (R1) |
| 9 | (a,b,c)Total leaf number at flowering (V8) | (a,c)Flowering (R1) | |
| 10 | (a,b,c)Green leaf number at flowering (V9) | ||
| 11 | (a,b,c)Yellow leaf number at flowering (V10) | ||
| 12 | (a,b,c)Fresh biomass (V11) | ||
| 13 | (a,b,c)Shoot length after harvest (V12) | ||
| 14 | (a,b)Root length (V13) | ||
| 15 | (a,b)Total plant height(V14) | ||
| 16 | (a,b,c) Dry biomass (V15) | ||
| 17 | (a,c)Days to flowering (R1) | ||
| 18 | (a,c)Unfilled grain weight (R2) | ||
| 19 | (a,c)Total grain weight (R3) | ||
| 20 | (ns)Filled grain weight (R4) | ||
| 21 | (ns)Panicle weight (R5) | ||
| 22 | (ns)Filled grain number (R6) | ||
| 23 | (ns)Total grain number (R7) | ||
| 24 | (a)Unfilled grain number (R8) | ||
| 25 | (a,b,c)Weight of panicle remains (R9) |
Twenty of the 25 parameters were confirmed as N-responsive based on the significance test and shown in the 1st column. Ten of these parameters shortlisted from Feature selection and network analyses were subjected to correlation analysis with grain yield in normal and low N and those parameters that significantly correlated with yield at low N are shown in the 2nd column. NUE was calculated as yield per unit N input for all genotypes/treatments and their correlation with each of these 10 parameters was analyzed. Those that significantly correlated with NUE are shown in the 3rd column. The superscripted alphabet a/b/c over the parameter I first column denotes parameter in combined nitrate and urea N, only nitrate N and only urea N.