Relationship of Leaf Elongation to Forage Yield of Tall Fescue Genotype¹

Abstract

Forage yield is usually not closely related to CO2 exchange rate of single leaves, and existing data suggest other factors such as canopy characters need to be studied. Therefore, we investigated the relationship between leaf elongation rate and forage yield of 14 genotypes of tall fescue (Festuca arundinacea, Schreb.). Plants were grown in the field under summer water stress and with irrigation. Leaf elongation 4, 8, or 16 days after defoliation was related positively to forage yield at the subsequent harvest during the post‐flowering period. Generally correlations with yield were best (r ≥ 0.67 in 11 of 14 sampling periods) for the 16‐day elongation measurement. Significant differences in leaf elongation at 16 days were noted among genotypes for each of the sampling periods for both irrigated and water‐stressed treatments. Differences among genotypes in leaf elongation were not always consistent from date to date indicating some genotype by environment interaction for this character. Range in leaf length and variance attributable to clones were greater under irrigation which suggested that selection would be more efficient with a good growing environment. Broad‐sense heritabilities for leaf elongation at 16 days calculated for data pooled over 2 years were 0.87 and 0.88 for the water‐stressed and irrigated treatment, respectively. Amount of leaf elongation 12 to 16 days after cutting may be a good estimator of subsequent forage yield because it would indicate the degree of radiation interception during early stages of regrowth, and also the rate of achievement of the critical leaf area index. Leaf elongation rate may be an acceptable criterion for estimating regrowth vigor and yield potential of clones and populations in breeding programs.

Morphogenetic adaptation to defoliation and soil fertility in perennial ryegrass (Lolium perenne)

“…The data presented here conform with those of other studies (Horst et al 1978;Hazard & Ghesquiere 1997). There was a negative relationship between leaf growth and tiller number which, unfortunately, remained strong regardless of the defoliation frequency or the soil fertility.…”

“…numerous small tillers (Rhodes & Mee 1980;Nelson & Sleper 1981;Hazard et al 1996). Ryegrass with large tillers and rapid leaf elongation rate yields more herbage under lenient defoliation (Horst et al 1978;Hazard et al 1994;Hazard & Ghesquiere 1997), while small tillers with high tiller density give a slightly better yield under a severe defoliation regime (Rhodes 1971;Sugiyama 1987;Hazard et al 1994;Hazard & Ghesquiere 1997).…”

Morphogenetic and structural comparative characterization of tropical forage grass cultivars under free growth

“…(Piracicaba, Braz. ), v.67, n.2, p.136-142, March/April 2010 netic responses and dynamics of herbage accumulation, since it has a high positive correlation with sward herbage mass (Horst et al, 1978). As a result, the two cultivars of B. humidicola (Comum and Tupi) and of B. decumbens (Basilisk) presented the lowest potential of leaf accumulation, the opposite of the two cultivars of P. maximum (Mombaça and Tanzânia).…”

Frequencies and intensities of defoliation in Aruana guineagrass swards: morphogenetic and structural characteristics

“…Leaf elongation rate showed to be the morphogenetic variable that best directly correlates with forage dry matter (Horst et al, 1978) and it was affected by environmental and grazing factors in this study. Effects caused by season of the year (P<0.05) and the LI × post grazing height interaction (P<0.05) were observed.…”