organic acids and symbiosis with mycorrhizal fungi that increases Pi foraging ( Dixon et al., 2020 ). Crop-specific knowledge of root architecture traits that contribute to Pi efficiency is of fundamental importance. First, such information can contribute
Arthur Villordon, Jeffrey C. Gregorie, and Don LaBonte
Sameer Pokhrel, Bo Meyering, Kim D. Bowman, and Ute Albrecht
-endemic environment. It is well documented that different rootstock cultivars exhibit differences in their root architecture ( Albrecht et al., 2020 ; Castle and Youtsey, 1977 ; Eissenstat, 1991 ) that contribute to their influence on the aboveground horticultural
Erick G. Begitschke, James D. McCurdy, Te-Ming Tseng, T. Casey Barickman, Barry R. Stewart, Christian M. Baldwin, Michael P. Richard, and Maria Tomaso-Peterson
herbicide application is lacking. Therefore, research was conducted to determine the effects of preemergence herbicides commonly used on sod farms on hybrid bermudagrass root architecture and to provide some insight into the effects of these preemergence
Ute Albrecht, Mireia Bordas, Beth Lamb, Bo Meyering, and Kim D. Bowman
is a direct consequence of infection with CLas, often occurring before disease symptoms become apparent ( Johnson et al., 2014 ). Therefore, root architecture is likely to influence resilience of a commercial citrus tree to HLB and to other biotic or
Gerardo H. Nunez, Hilda Patricia Rodríguez-Armenta, Rebecca L. Darnell, and James W. Olmstead
than all other families. Seedlings in families P1 and P2 had greater percentage of their root systems in the top 8 cm of soil than seedlings in families P3 and P4. Root architecture differences between families P2 and P3 can be observed in Fig. 2
Jeffrey S. Beasley, Bruce E. Branham, and Loretta M. Ortiz-Ribbing
Trinexapac-ethyl (TE) [4-(cyclopropyl-a-hydroxy-methylene)-3,5-dioxocyclohexanecarboxylic acid ethyl ester] effects on turfgrass root architecture are not known. It has been postulated that PGR application could cause photoassimilate that is normally used for shoot growth to be funneled to root growth. This study evaluated the effects of a single TE application on kentucky bluegrass (KBG) root and shoot growth for seven weeks. Individual KBG plants were grown in a hydroponic system and harvested weekly. At each harvest, tiller height, tiller number, and color ratings were recorded. Estimates of total root length (TRL), root surface area (SA), and average root diameter were measured using the WinRhizo system. Trinexapac-ethyl reduced plant height for 4 weeks followed by a period of postinhibition growth enhancement. Trinexapac-ethyl increased tiller number over the course of the study and slightly enhanced plant color. Trinexapac-ethyl reduced TRL and SA 48% and 46% at 1 week after treatment (WAT) followed by an accelerated growth rate 1 to 4 WAT. Trinexapac-ethyl had no effect on root diameter. On a tiller basis, TE initially reduced TRL and SA 30% and 31%, respectively. Total root length per tiller and root surface area per tiller were reduced by TE treatment, but by 7 WAT, those differences were no longer significant. Initial reductions in TRL and SA per tiller may reduce tiller competitiveness for water and nutrients. Based on data for TRL and SA per tiller, shoot and root growth must be considered in total to fully understand TE effects on plant growth. Field research is needed to corroborate results from hydroponic-studies and examine the effect of various TE rates and multiple applications on turfgrass root and shoot growth.
Arthur Villordon and Jeffrey C. Gregorie
and environmental variables that control RSA development contribute to the understanding of storage root formation and productivity. The primary objective of this work was to generate species-dependent information about root architectural responses to
Arthur Villordon, Don LaBonte, Nurit Firon, and Edward Carey
macronutrients from the soil ( Casimiro et al., 2003 ). Our current understanding of the regulation of root architecture is based on a subset of well-characterized “model” species including major global food crops such as wheat, rice, and maize. In sweetpotatoes
Sandra R. Menasha* and Milton E. Tignor
Sweet corn (Zea mays L.) is difficult to transplant due to poor root regeneration. Despite reduced yields, growers are transplanting sweet corn to hasten maturity time to target profitable early markets in the Northeast. Researchers have ascribed the negative impacts on yield to restricted rooting volume. Therefore, the impacts plug cell volume had on sweet corn transplant root architecture and biomass accumulation were investigated. `Temptation' sweet corn was sown in volumes of 15, 19, 14, and 29 mL correlating to transplant plug trays with plug counts of 200, 162, 128, and 72 plugs per tray. Plug cells were exposed to three substrate environments; a dairy manure based organic compost media, a commercial soil-less germination mix, and the soil-less media supplemented 2X with 200 ppm soluble 3-3-3 organic fertilizer. A 4 × 3 factorial randomized complete-block experimental design with two blocks and five replicates per treatment was repeated twice in the greenhouse. For each experiment a total of three center cells were harvested from each replicate for analysis using the WinRhizo Pro root scanning system (Regent Instruments Inc., Montreal). Three cells per treatment were also transplanted into 8-inch pots to stimulate field transplanting. Based on mean separation tests (n = 30), increased cell volume before transplanting significantly increased root surface area, average diameter, and root volume after transplanting (n = 18). Mean root surface area for a 29-mL cell was 30% greater than a 15-mL cell before transplanting and 22% greater after transplanting. Plug cell volume also significantly impacted shoot and root biomass (P <0.0001). A 14-mL increase in cell volume resulted in a root and shoot dry weight increase of about 15%.
Dario Stefanelli and Ronald L. Perry
One of the main problems facing organic horticulture is orchard ground floor management. Several works report that ground floor management affects root architecture of fruit trees, changing the position and depth of the roots. The purpose of this work is to study the effects of orchard ground floor management systems (GFMS) in an apple orchard under organic protocol in Michigan. The research was conducted at the Clarksville Horticultural Experimental Station of Michigan State University, in the organically certified (by OCIA) orchard of `Pacific Gala' grafted on M9 NAKB 337, established in May 2000. The GFMS being studied are: 1) mulch (MU) made of alfalfa hay on the tree rows, with a width of 2 m; 2) “Swiss Sandwich System” (SSS) that consists in superficial tillage of two strips 90 cm wide at each side of the tree row, leaving a 40-cm strip in the middle (under the canopy) where volunteer vegetation is allowed to grow; 3) flaming (FL) of the weeds in a 2-m strip underneath the tree canopy by a propane burner. Root architecture was studied in Sept. 2005 through the frequency of roots by the profile wall method. Trenches (3.36-m long × 1.32-m deep) were dug in the soil 45 cm from the tree trunk. Two 158 cm × 130 cm metal grid frames divided by strings into a 28 cm × 22 cm grid were placed against the profile faces to facilitate the counting and mapping of the root distribution. The GFMS did affect the root distribution of the two classes of roots under study (<2 mm and >2mm). In the FL and MU treatments, roots were noticed to be superficial and their frequency was higher close to the tree. In SSS, root frequency was similar until 80 cm deep in the soil profile and they extended farther from the tree.