We extracted information from 24 published papers on QTLs controlling 29 root parameters including root number, maximum root length, root thickness, root/shoot ratio, and root penetration index.
Data on root characteristics such as number of roots per plant, root volume, roots dry weight, maximum root length and root thickness were recorded.
At harvest data on maximum root length, root thickness, root volume, total root number, root dry weight and shoot dry weight were recorded.
Fig. 5 Maximum root reinforcement as a function of distance from tree stem for stems of different diameters (0.15, 0.2, 0.25, and 0.3 m DBH) calculated with the RBMw calibrated with the two datasets a = Gisborne (G), b = Palmerston North (PN).
Comparison of trench P1 with P2 shows how maximum root diameter at one quarter of the distance between stems is coarser than at half the distance between stems.
Hence, for each distance from a tree, a maximum root diameter (RDmax) is computed as an upper bound for root diameter distribution.
The results show that the maximum root diameter present in a bundle decreases with increasing distance from the stem.
The importance of fine-root density in determining the magnitude of root bundle tensile strength is shown in Fig. 5 in comparison to the results of Fig. 2b, where the maximum root reinforcement for a tree with 0.3 m DBH is expected at about 1.9 m, exactly at the distance where the maximum intensity of fine-root density is reached.
Below-ground growth measurements included maximum root depth and maximum root spread, hereafter referred to as root depth and root spread.
For maxima detection, we imposed a minimum maxima-to-maxima distance criterion of 10 mm.
