Seasonal Changes in Nonstructural Carbohydrate Levels and Innovation Number of Kentucky Bluegrass Turf Growing in Three Plant‐Climate Areas¹

Abstract

Controlled environment studies have shown temperature to be one of the most important factors controlling nonstructural carbohydrate levels and density of Kentucky bluegrass (Poa pratensis L.) turf. Little information is available showing similar responses to temperature on a seasonal basis in the field. The objective of this experiment was to determine how nonstructural carbohydrate levels and density of Kentucky bluegrass turf differ among climatic areas and from season to season within an area. Total nonstructural carbohydrates (TNC) and innovation development were studied in five Kentucky bluegrass cultivars grown in the field in three distinct climate areas of California. These are a maritime climate of coastal southern California, a southern California interior valley thermal belt, and a temperate mountain valley. The respective soils of these areas are San Emigdio sandy loam classified as coarse‐loamy, mixed (calcareous), thermic Typic Xerofluvents; Arlington fine sandy loam classified as coarse‐loamy, mixed, thermic Haplic Durixeralf; and Havala sandy loam classified as fine‐loamy, mixed, thermic Typic Argixerolls. Results showed that changes in TNC levels and numbers of innovations followed seasonal patterns which were closely associated with the prevailing temperatures of each specific location. Consistently high summer temperatures reduced TNC stores but moderate temperatures did not affect them. Brief periods of exceptionally high temperature also reduced TNC levels. Accumulation of TNC occurred at each location at the time when temperatures were well below optimum for growth at that location. In the cold winter location, TNC levels decreased during the winter months. Flushes of growth occurring in spring depleted TNC. Density, the number of innovations per unit area, decreased throughout the summer at the high temperature location but increased through the cool winter. In the location of moderate summer and winter temperatures the number of innovations remained high and showed less seasonal fluctuation. Temperature, rather than day length, appeared to be the primary factor affecting innovation development.

Physiological Changes during Cold Acclimation of Perennial Ryegrass Accessions Differing in Freeze Tolerance

“…The accumulation of WSC during cold acclimation is well documented in many turfgrass species (Youngner et al, 1978; Dionne et al, 2001b; Shahba et al, 2003). Water soluble carbohydrates have been shown to depress cellular freezing point, enhance osmotic adjustment, and increase membrane stability at freezing temperatures (Santarius, 1982).…”

Morphological and Physiological Characteristics Associated with Heat Tolerance in Creeping Bentgrass

“…A decrease in tiller density could be a major factor contributing to turf quality decline because density is one of the three components in quality evaluation (Beard, 1999; Turgeon, 1999). Declines in tiller density with increasing temperatures have been found in various cool‐season grass species (Thomas and Norris, 1977; Youngner and Nudge, 1976; Youngner et al, 1978; Davies and Thomas, 1983). Lower tiller density results in reduced leaf area available for photosynthesis and, thus, can lead to decreases in canopy photosynthetic rate (Auda et al, 1966).…”

“…Declines in tiller density tolerance (Huang and Liu, 1999;Huang and Gao, 2000; with increasing temperatures have been found in various Liu and Huang, 2000a,b;Toubakaris and McCarty, 2000; cool-season grass species (Thomas and Norris, 1977;Xu and Huang, 2000a,b). Youngner and Nudge, 1976;Youngner et al, 1978;Davies and Thomas, 1983). Lower tiller density results in MATERIALS AND METHODS reduced leaf area available for photosynthesis and, thus, can lead to decreases in canopy photosynthetic rate Sod pieces of L-93 and Penncross were collected from the (Auda et al, 1966).…”

Seasonal fluctuations in growth/decline and single-leaf gas exchange of C3 turfgrass fields under various light conditions

“…Xu and Huang (2000 a, b;2001 a, b) showed that high soil temperature caused a decline in net photosynthesis at the single-leaf and canopy scales, leading to less carbon allocation to the root and a decline in the root growth of creeping bentgrass. Other studies have reported declines in the carbohydrate content of C3 turfgrasses during the summer (Sweeney et al, 2001;Youngner et al, 1978). Xu and Huang (2003) also showed a decline in turf quality, carbohydrate content and allocation to Full Paper roots during the summer.…”