LEAF AREA AND PHOTOSYNTHESIS - COMPONENTS OF GROWTH IN BLACK WALNUT (JUGLANS NIGRA L.) CLONES
Abstract
Physiological variables possibly related to growth rate in black walnut clones were measured to determine their usefulness for indirect selection. Variables measured included net photosynthesis, dark respiration, leaf resistance, net assimilation rate, leaf area, leaf dry weight, chlorophyll a and b content, and total chlorophyll content. Greenhouse grafts of clones of known growth rate constituted the experimental material. Specific leaf area (SLA = leaf area/leaf dry weight) was calculated. A variable, compound leaf area efficiency (CLAE), the ratio of actual leaf area to the area of the outline of the compound leaf was also calculated. This variable gives an expression of how well the leaf approaches the light interception capability of a simple leaf. Specific leaf area of the leaf outline (SLA(,0)), a ratio of SLA/CLAE, was also calculated. ANOVA indicated the clonal factor for CLAE and SLA(,0) to be significant at (alpha) = 0.001 and for SLA, chlorophyll a, chlorophyll b, chlorophyll a + b to be significant at (alpha) = 0.01 and net assimilation rate at (alpha) = 0.05. All other variables were nonsignificant at (alpha) = 0.05. The clonal means for these values were then used as independent variables in regression analysis with the standardized means for volume, height, and DBH from the field grown grafts (8-12 years old) as the dependent variables. Regression equations using CLAE and SLA or SLA(,0) alone gave the best precision with the simplest measurements. The resulting equations using CLAE and SLA had respective R('2) values of 0.65, 0.84, and 0.57 for volume, height, and DBH and using SLA(,0) alone gave r('2) values of 0.64, 0.92, and 0.57, respectively. The corresponding correlation coefficients are of sufficient magnitude to allow indirect selection in approximately two months, the time to graft and evaluate a clone.
Degree
Ph.D.
Subject Area
Forestry
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.