Decreased Cell Wall Research Articles

EFFECT OF PROCESSING METHODS ON THE IN VITRO DIGESTIBILITY OF SODIUM HYDROXIDE TREATED ROUGHAGES

The response of roughages to sodium hydroxide (NaOH) treatment varied with type of roughage. Treatment with NaOH at 23 C for 24 hr increased in vitro dry matter digestibility (IVDMD) by 8,5, 39.6 and 21.5 percentage units for alfalfa stem, barley straw and corn stover, respectively. Increased IVDMD values were brought about, in part, by increased water solubility and decreased cell wall constituents. No significant changes occurred in acid detergent fiber, cellulose or lignin content. The IVDMD values of barley straw ranged from 38% at 0% NaOH to 81% with 12% NaOH at 130 C. At all temperatures and durations, IVDMD increased with increase in concentration of NaOH up to the 8% level. Above 8% NaOH, no further increase in IVDMD occurred. Temperature affected the rate as well as the extent of the response to NaOH. Treatments at 100 C for 90 min resulted in IVDMD values approximately 10 percentage units higher than at 23 C for 24 hr.

Effect of Leaf Aging on Water Deficit—Water Potential Relationships of Dogwood Leaves Growing in Two Environments

AbstractWater deficit‐water potential relationships were determined at approximately monthly intervals from May to August on leaves collected from dogwood trees growing in two environments. The relationships were not the same for leaves of different ages or for leaves of the same age, but growing in the different environments. With aging of the leaves, the relationships shifted to progressively lower water potentials for a given water deficit. Increased leaf dry weight, decreased cell wall elasticity, and decreased osmotic potentials accompanied leaf aging. These changes and the shifts in the relationships were greatest for leaves growing under high light intensity and dry environmental conditions. The lack of constancy in the relationships reduces the usefulness of water deficit or relative turgidity as an estimator of water potential. For the purposes of some workers, however, the relationships may be sufficiently constant for mature leaves of a given species growing in a relatively constant environment.