Author Contributions
Conceptualization, M.S.U., M.G.A., M.B., S.A.B., P.L.B., A.B.M.K., and N.H.; methodology, M.S.U., M.G.A., M.B., S.A.B., P.L.B., A.B.M.K., and N.H.; software, M.S.U.; validation, M.S.U., M.G.A., M.B., S.A.B., P.L.B., A.B.M.K., and N.H.; formal analysis, M.S.U. and A.H.; investigation, M.S.U., M.G.A., M.B., S.A.B., P.L.B., A.B.M.K., and N.H.; resources, M.S.U.; data curation, M.S.U. and A.H.; writing—original draft preparation, M.S.U., M.G.A., M.B., S.A.B., P.L.B., A.B.M.K., and N.H.; writing—review and editing A.G., Y.S.A., A.A.A., and A.H.; visualization, M.S.U., M.G.A., M.B., S.A.B., P.L.B., A.B.M.K., and N.H.; supervision, A.G., Y.S.A., and M.S.U.; project administration, M.S.U., A.G., Y.S.A., and A.A.A.; funding acquisition, A.G., Y.S.A., A.A.A., and A.H. All authors have read and agreed to the published version of the manuscript.
Acknowledgments
The research was conducted at the Institute of Crop Sciences, Graduate School of Chinese Academy of Agricultural Sciences (CAAS), Haidian District, Beijing 100081, under the National Agricultural Technology Program-Phase II Project (NATP-2), Bangladesh Agricultural Research Council (BARC), Ministry of Agriculture, Bangladesh. The authors extend their appreciation to the Taif University Researchers Supporting Project number (TURSP 2020/78), Taif University, Taif, Saudi Arabia. We also thank Yunbi Xu and Wne-Xue Li, Institute of Crop Sciences, Chinese Academy of Agricultural Sciences (CAAS), Haidian District, Beijing 100081, for their scientific guidance and encouragement throughout the course of the PhD study.
Figure 1.
Maize root network system (RNS) of selected low-phosphorus-susceptible (G94) and tolerance genotypes (G53) grown under Normal-P (NP) and Low-P (LP) conditions under hydrophonic condition.
Figure 1.
Maize root network system (RNS) of selected low-phosphorus-susceptible (G94) and tolerance genotypes (G53) grown under Normal-P (NP) and Low-P (LP) conditions under hydrophonic condition.
Figure 2.
The processing phases for root investigation with the GiA Roots software [
25].
Figure 2.
The processing phases for root investigation with the GiA Roots software [
25].
Figure 3.
Effect of LP and NP treatments on maize germplasm for measured traits. The box plot’s edges depict the upper and lower quintiles, as well as the median, which is depicted in the box’s center. Genotypes that do not fit inside the rank of whisker are indicated by a circle. Note: ARW = Average root width, NWB = Network bushiness, NCC = Number of connected components, NWD = Network depth, EAR = Ellipse axis ratio, NWLD = Network length distribution, MJEA = Major ellipse axis, MANR = Maximum number of roots, NWW = Network width, MENR = Median number of roots, MIEA = Minor ellipse axis, NWA = Network area, NWCA = Network convex area, NWP = Network perimeter, NWS = Network solidity, SRL = Specific root length, NWSA = Network surface area, NWL = Network length, NWV = Network volume, NWWDR = Network width to depth ratio.
Figure 3.
Effect of LP and NP treatments on maize germplasm for measured traits. The box plot’s edges depict the upper and lower quintiles, as well as the median, which is depicted in the box’s center. Genotypes that do not fit inside the rank of whisker are indicated by a circle. Note: ARW = Average root width, NWB = Network bushiness, NCC = Number of connected components, NWD = Network depth, EAR = Ellipse axis ratio, NWLD = Network length distribution, MJEA = Major ellipse axis, MANR = Maximum number of roots, NWW = Network width, MENR = Median number of roots, MIEA = Minor ellipse axis, NWA = Network area, NWCA = Network convex area, NWP = Network perimeter, NWS = Network solidity, SRL = Specific root length, NWSA = Network surface area, NWL = Network length, NWV = Network volume, NWWDR = Network width to depth ratio.
Figure 4.
Estimated heritability for twenty traits. ARW = Average root width, NWB = Network bushiness, NCC = Number of connected components, NWD = Network depth, EAR = Ellipse axis ratio, NWLD = Network length distribution, MJEA = Major ellipse axis, MANR = Maximum number of roots, NWW = Network width, MENR = Median number of roots, MIEA = Minor ellipse axis, NWA = Network area, NWCA = Network convex area, NWP = Network perimeter, NWS = Network solidity, SRL = Specific root length, NWSA = Network surface area, NWL = Network length, NWV = Network volume, NWWDR = Network width to depth ratio.
Figure 4.
Estimated heritability for twenty traits. ARW = Average root width, NWB = Network bushiness, NCC = Number of connected components, NWD = Network depth, EAR = Ellipse axis ratio, NWLD = Network length distribution, MJEA = Major ellipse axis, MANR = Maximum number of roots, NWW = Network width, MENR = Median number of roots, MIEA = Minor ellipse axis, NWA = Network area, NWCA = Network convex area, NWP = Network perimeter, NWS = Network solidity, SRL = Specific root length, NWSA = Network surface area, NWL = Network length, NWV = Network volume, NWWDR = Network width to depth ratio.
Figure 5.
Correlation between BLUP and mean of each accession in the maize germplasm. ARW = Average root width, NWB = Network bushiness, NCC = Number of connected components, NWD = Network depth, EAR = Ellipse axis ratio, NWLD = Network length distribution, MJEA = Major ellipse axis, MANR = Maximum number of roots, NWW = Network width, MENR = Median number of roots, MIEA = Minor ellipse axis, NWA = Network area, NWCA = Network convex area, NWP = Network perimeter, NWS = Network solidity, SRL = Specific root length, NWSA = Network surface area, NWL = Network length, NWV = Network volume, NWWDR = Network width to depth ratio.
Figure 5.
Correlation between BLUP and mean of each accession in the maize germplasm. ARW = Average root width, NWB = Network bushiness, NCC = Number of connected components, NWD = Network depth, EAR = Ellipse axis ratio, NWLD = Network length distribution, MJEA = Major ellipse axis, MANR = Maximum number of roots, NWW = Network width, MENR = Median number of roots, MIEA = Minor ellipse axis, NWA = Network area, NWCA = Network convex area, NWP = Network perimeter, NWS = Network solidity, SRL = Specific root length, NWSA = Network surface area, NWL = Network length, NWV = Network volume, NWWDR = Network width to depth ratio.
Figure 6.
Dendrogram from UPGMA clustering for 220 maize inbreds using Euclidean genetic distances based on all RNS traits measured by GiA Roots.
Figure 6.
Dendrogram from UPGMA clustering for 220 maize inbreds using Euclidean genetic distances based on all RNS traits measured by GiA Roots.
Figure 7.
A G × T is based on relative RNS traits of maize.
Figure 7.
A G × T is based on relative RNS traits of maize.
Figure 8.
Germplasm ranking and selected germplasm from 220 maize germplasm through multi-trait genotype-ideotypes distance index (MGIDI) considering 5% selection intensity.
Figure 8.
Germplasm ranking and selected germplasm from 220 maize germplasm through multi-trait genotype-ideotypes distance index (MGIDI) considering 5% selection intensity.
Figure 9.
The strengths and weaknesses of all the genotypes (FA = Factor Analysis).
Figure 9.
The strengths and weaknesses of all the genotypes (FA = Factor Analysis).
Table 1.
Composition of nutrients for LP treatment.
Table 1.
Composition of nutrients for LP treatment.
Sl. No | Name of the Chemical | Net Weight (g)/10 L | Volume Needs for 50 L Stock Solution |
---|
01 | Calcium Nitrate {Ca(NO3)2·4H2O} | 944.6 | 250 mL |
02 | Potassium Sulfate (K2SO4) + Magnesium Sulfate (MgSO4) | 261.39 + 324.12 | 250 mL |
03 | Potassium Chloride (KCl) | 14.9 | 250 mL |
04 | Potassium dihydrogen phosphate (KH2PO4) | 68.046 | 2.5 mL |
05 | Boric Acid (H3BO4) | 0.6108 | 5 mL |
06 | Manganese sulfate (MnSO4) + Copper sulfate (CuSO4·5H2O) + Zinc sulfate (ZnSO4·5H2O) + {(NH4)6·Mo7·O24·4H2O} | 1.690 + 0.25 + 2.87 + 0.062 | 5 mL |
07 | Iron sodium salt Fe-EDTA | 146.82 | 250 mL |
Table 2.
Composition of nutrients for NP treatment.
Table 2.
Composition of nutrients for NP treatment.
Sl. No | Name of the Chemical | Net Weight (g)/10 L | Volume Needs for 50 L Stock Solution |
---|
01 | Calcium Nitrate {Ca(NO3)2·4H2O} | 944.6 | 250 mL |
02 | Potassium Sulfate (K2SO4) + Magnesium Sulfate (MgSO4) | 261.39 + 324.12 | 250 mL |
03 | Potassium Chloride (KCl) | 14.9 | 250 mL |
04 | Potassium dihydrogen phosphate (KH2PO4) | 68.046 | 250 mL |
05 | Boric Acid (H3BO4) | 0.618 | 5 mL |
06 | Manganese sulfate (MnSO4) + Copper sulfate (CuSO4·5H2O) + Zinc sulfate (ZnSO4·5H2O) + {(NH4)6·Mo7·O24·4H2O} | 1.690 + 0.25 + 2.87 + 0.062 | 5 mL |
07 | Iron sodium salt Fe-EDTA | 146.82 | 250 mL |
Table 3.
Descriptive statistics for tested traits under LP and NP treatments.
Table 3.
Descriptive statistics for tested traits under LP and NP treatments.
Traits | Treat. | Mean | SE | Minimum | Maximum | Median | Mode | Kurtosis | Skewness |
---|
ARW | NP | 4.52 | 0.02 | 3.00 | 6.53 | 4.44 | 6.01 | −0.38 | 0.46 |
LP | 4.45 | 0.02 | 3.41 | 6.52 | 4.40 | 4.12 | −0.05 | 0.62 |
NWB | NP | 1.62 | 0.01 | 1.12 | 4.96 | 1.45 | 1.50 | 7.91 | 2.50 |
LP | 1.54 | 0.01 | 1.10 | 6.50 | 1.39 | 1.33 | 20.68 | 3.40 |
NCC | NP | 43.89 | 0.42 | 3.00 | 91.00 | 44.00 | 43.00 | −0.11 | 0.13 |
LP | 46.15 | 0.37 | 5.00 | 112.00 | 45.00 | 44.00 | 0.64 | 0.38 |
NWD | NP | 2290.35 | 2.17 | 910.00 | 2303.00 | 2303.00 | 2303.00 | 158.25 | −11.45 |
LP | 2297.84 | 1.25 | 926.00 | 2303.00 | 2303.00 | 2303.00 | 634.59 | −22.55 |
EAR | NP | 0.76 | 0.00 | 0.11 | 0.99 | 0.79 | 0.84 | −0.24 | −0.56 |
LP | 0.82 | 0.00 | 0.26 | 1.00 | 0.85 | 0.84 | 0.24 | −0.87 |
NWLD | NP | 0.53 | 0.01 | 0.11 | 3.07 | 0.46 | 0.24 | 8.27 | 2.20 |
LP | 0.44 | 0.01 | 0.06 | 2.99 | 0.41 | 0.61 | 26.59 | 3.20 |
MJEA | NP | 3105.60 | 15.08 | 823.57 | 5072.72 | 3001.58 | 2632.98 | 0.05 | 0.47 |
LP | 2972.72 | 11.85 | 830.81 | 4465.25 | 2856.90 | 2679.85 | 0.33 | 0.66 |
MANR | NP | 77.86 | 1.25 | 5.00 | 253.00 | 62.00 | 56.00 | −0.51 | 0.64 |
LP | 83.14 | 1.24 | 7.00 | 237.00 | 69.00 | 44.00 | −0.55 | 0.70 |
NWW | NP | 2956.82 | 13.59 | 179.00 | 3455.00 | 3116.00 | 3455.00 | 3.19 | −1.54 |
LP | 2979.72 | 11.07 | 249.00 | 3455.00 | 3046.00 | 3455.00 | 2.48 | −1.22 |
MENR | NP | 52.43 | 0.97 | 2.00 | 223.00 | 42.00 | 21.00 | 0.52 | 1.02 |
LP | 57.32 | 0.97 | 4.00 | 177.00 | 45.00 | 37.00 | 0.48 | 1.08 |
MIEA | NP | 2310.48 | 7.83 | 239.24 | 2972.45 | 2353.58 | 2201.84 | 8.46 | −1.97 |
LP | 2386.18 | 6.64 | 213.02 | 3162.82 | 2398.86 | 2255.16 | 7.44 | −1.09 |
NWA | NP | 85,2169.61 | 12,698.0 | 28,448.00 | 2,306,467.00 | 766,588.00 | 425,187.00 | −0.21 | 0.67 |
LP | 927,120.77 | 12,626.3 | 33,913.00 | 2,380,819.00 | 828,074.00 | 1,399,665.00 | −0.15 | 0.72 |
NWCA | NP | 6,256,640.0 | 33,659.7 | 331,902.00 | 7,899,088.00 | 6,517,483.75 | 4,864,456.50 | 2.12 | −1.20 |
LP | 6,326,244.7 | 26,555.5 | 148,855.50 | 7,907,468.00 | 6,493,552.25 | 4,333,747.00 | 2.02 | −0.99 |
NWP | NP | 419,776.22 | 7310.85 | 10,665.00 | 1,449,259.00 | 346,500.50 | 149,445.00 | 0.20 | 0.88 |
LP | 455,401.13 | 7309.86 | 11,192.00 | 1,372,171.00 | 375,264.00 | 709,723.00 | 0.21 | 0.95 |
NWS | NP | 0.14 | 0.00 | 0.02 | 0.47 | 0.12 | 0.09 | 0.84 | 1.11 |
LP | 0.15 | 0.00 | 0.03 | 0.46 | 0.13 | 0.32 | 0.23 | 1.00 |
SRL | NP | 0.05 | 0.00 | 0.02 | 0.10 | 0.04 | 0.03 | 0.43 | 0.70 |
LP | 0.05 | 0.00 | 0.02 | 0.08 | 0.05 | 0.05 | −0.61 | 0.27 |
NWSA | NP | 3,523,843.5 | 53,442.4 | 109,925.66 | 9,490,765.02 | 3,153,257.77 | 1,669,954.28 | −0.20 | 0.69 |
LP | 3,832,697.7 | 53,021.9 | 127,452.83 | 10,048,319.6 | 3,407,774.88 | 5,810,109.73 | −0.12 | 0.73 |
NWL | NP | 265,436.89 | 4685.19 | 6132.00 | 975,158.00 | 219,807.50 | 88,374.00 | 0.23 | 0.89 |
LP | 287,929.75 | 4665.79 | 6225.00 | 879,854.00 | 238,309.00 | 449,101.00 | 0.24 | 0.96 |
NWV | NP | 5,462,435.1 | 71,955.11 | 204,831.84 | 13,046,946.3 | 5,082,050.76 | 3,397,327.72 | −0.53 | 0.43 |
LP | 5,916,641.1 | 70,714.1 | 256,796.93 | 13,200,212.0 | 5,630,054.48 | 8,591,461.09 | −0.62 | 0.39 |
NWWDR | NP | 1.29 | 0.01 | 0.12 | 1.57 | 1.35 | 1.50 | 2.52 | −1.41 |
LP | 1.30 | 0.00 | 0.27 | 1.68 | 1.32 | 1.50 | 1.79 | −1.13 |
Table 4.
Analysis of variance of the different RNS tested traits.
Table 4.
Analysis of variance of the different RNS tested traits.
Traits | Treatment | Mean Square | F-Value (Gen) | Significance Level |
---|
Replication | Genotype | Error |
---|
ARW | NP | 0.04 | 1.45 | 0.09 | 15.69 | *** |
LP | 0.02 | 0.93 | 0.07 | 14.2 | *** |
NWB | NP | 0.04 | 0.78 | 0.07 | 10.83 | *** |
LP | 0.07 | 0.61 | 0.08 | 7.78 | *** |
NCC | NP | 13.07 | 648.64 | 95.46 | 6.80 | *** |
LP | 83.32 | 482.43 | 93.30 | 5.17 | *** |
NWD | NP | 161.82 | 11,386.40 | 4695.10 | 2.43 | *** |
LP | 838.02 | 2807.12 | 2030.71 | 1.38 | * |
EAR | NP | 0.01 | 0.06 | 0.01 | 12.7 | * |
LP | 0.01 | 0.03 | 0.01 | 5.30 | *** |
NWLD | NP | 0.03 | 0.27 | 0.03 | 8.11 | *** |
LP | 0.01 | 0.11 | 0.02 | 6.03 | *** |
MJEA | NP | 76,230.1 | 916,523 | 103,873 | 8.82 | *** |
LP | 99,507.1 | 486,751 | 71,573.5 | 6.80 | *** |
MANR | NP | 12.857 | 7172.570 | 442.848 | 16.2 | *** |
LP | 229.32 | 7031.23 | 456.18 | 15.41 | *** |
NWW | NP | 64,219.4 | 696,475 | 100,280 | 6.95 | *** |
LP | 57,281.70 | 407,323.00 | 85,124.00 | 4.79 | *** |
MENR | NP | 12.86 | 7172.57 | 442.85 | 16.2 | *** |
LP | 229.32 | 7031.23 | 456.18 | 15.41 | *** |
MIEA | NP | 76,230.1 | 916,523 | 103,873 | 8.82 | *** |
LP | 99,507.10 | 486,751.00 | 71,573.50 | 6.80 | *** |
NWA | NP | 851,326,000.00 | 756,240,000,000.00 | 38,367,000,000.00 | 19.71 | *** |
LP | 27,187,900,000.00 | 761,409,000,000.00 | 40,363,800,000.00 | 18.86 | *** |
NWCA | NP | 663,782,000,000.00 | 4,530,370,000,000.00 | 528,786,000,000.00 | 8.57 | *** |
LP | 217,830,000,000.00 | 2,475,580,000,000.00 | 428,953,000,000.00 | 5.77 | *** |
NWP | NP | 120,272,000.00 | 246,041,000,000.00 | 14,265,200,000.00 | 17.25 | *** |
LP | 9,820,570,000.00 | 252,527,000,000.00 | 14,005,400,000.00 | 18.03 | *** |
NWS | NP | 0.001 | 0.025 | 0.001 | 16.83 | *** |
LP | 0.001 | 0.026 | 0.001 | 19.64 | *** |
SRL | NP | 0.00003 | 0.00055 | 0.00004 | 14.78 | *** |
LP | 0.00001 | 0.00036 | 0.00003 | 13.06 | *** |
NWSA | NP | 12,716,500,000.00 | 13,361,400,000,000.00 | 690,971,000,000.00 | 19.34 | *** |
LP | 523,286,000,000.00 | 13,377,900,000,000.00 | 721,558,000,000.00 | 18.54 | *** |
NWL | NP | 65,982,000.00 | 100,591,000,000.00 | 6,010,840,000.00 | 16.73 | *** |
LP | 4,479,120,000.00 | 102,500,000,000.00 | 5,795,460,000.00 | 17.69 | *** |
NWV | NP | 120,369,000,000.00 | 24,219,600,000,000.00 | 1,252,990,000,000.00 | 19.33 | *** |
LP | 902,056,000,000.00 | 23,414,500,000,000.00 | 1,350,090,000,000.00 | 17.34 | *** |
NWWDR | NP | 0.01 | 0.12 | 0.02 | 6.72 | *** |
LP | 0.01 | 0.08 | 0.02 | 4.71 | *** |
Table 5.
Estimates of variance components (proportion of the total).
Table 5.
Estimates of variance components (proportion of the total).
Traits | Genotype | Genotype × Treatment | Treatment | Residual |
---|
ARW | 0.53 | 0.24 | 0.03 | 0.21 |
NWB | 0.53 | 0.14 | 0.01 | 0.33 |
NCC | 0.32 | 0.21 | 0.05 | 0.41 |
NWD | 0.01 | 0.14 | 0.01 | 0.84 |
EAR | 0.30 | 0.26 | 0.11 | 0.33 |
NWLD | 0.34 | 0.24 | 0.08 | 0.34 |
MJEA | 0.37 | 0.22 | 0.04 | 0.37 |
MANR | 0.55 | 0.20 | 0.03 | 0.22 |
NWW | 0.29 | 0.20 | 0.00 | 0.50 |
MENR | 0.56 | 0.19 | 0.03 | 0.21 |
MIEA | 0.16 | 0.31 | 0.05 | 0.48 |
NWA | 0.60 | 0.18 | 0.04 | 0.18 |
NWCA | 0.39 | 0.18 | 0.01 | 0.42 |
NWP | 0.57 | 0.19 | 0.04 | 0.20 |
NWS | 0.58 | 0.18 | 0.03 | 0.21 |
SRL | 0.50 | 0.24 | 0.01 | 0.26 |
NWSA | 0.59 | 0.18 | 0.04 | 0.19 |
NWL | 0.56 | 0.19 | 0.04 | 0.21 |
NWV | 0.60 | 0.17 | 0.04 | 0.19 |
NWWDR | 0.29 | 0.19 | 0.00 | 0.51 |
Table 6.
The first four PCs of traits eigen vectors of the maize inbreds.
Table 6.
The first four PCs of traits eigen vectors of the maize inbreds.
Parameter | PC1 | PC2 | PC3 | PC4 |
---|
ARW | −0.1955 | −0.0387 | 0.2908 | −0.3165 |
NWB | 0.0163 | 0.0311 | −0.2666 | 0.6438 |
NCC | 0.2166 | 0.0606 | 0.2587 | −0.0784 |
NWD | 0.2171 | 0.2043 | 0.1941 | 0.1486 |
EAR | 0.1465 | −0.1705 | 0.4498 | 0.3054 |
NWLD | −0.1413 | 0.2499 | −0.0488 | −0.1898 |
MJEA | 0.1008 | 0.4366 | −0.2509 | −0.2223 |
MANR | 0.2823 | −0.098 | −0.1934 | −0.0069 |
NWW | 0.2087 | 0.2918 | 0.2853 | 0.1004 |
MENR | 0.2823 | −0.098 | −0.1934 | −0.0069 |
MIEA | 0.1008 | 0.4366 | −0.2509 | −0.2223 |
NWA | 0.2952 | −0.1247 | −0.0122 | −0.1458 |
NWCA | 0.2387 | 0.2501 | 0.2458 | 0.0917 |
NWP | 0.2999 | −0.0692 | −0.0912 | −0.0696 |
NWS | 0.1752 | −0.3885 | −0.0632 | −0.16 |
SRL | 0.2249 | 0.046 | −0.3095 | 0.2565 |
NWSA | 0.2957 | −0.1204 | −0.016 | −0.1436 |
NWL | 0.2999 | −0.0651 | −0.0875 | −0.074 |
NWV | 0.2685 | −0.1737 | 0.0867 | −0.2503 |
NWWDR | 0.1947 | 0.3003 | 0.2624 | 0.0654 |
Cumulative% of total variance | 52.18 | 69.24 | 79.84 | 85.71 |