Protein and carbohydrate composition of lucerne grown in Canterbury

Abstract

Carbohydrate fractions and total nitrogen were measured in leaves and stems of Wairau lucerne grown in Canterbury. Leaves had lower levels of total soluble carbohydrate (3-5%), cellulose (8-10%) and lignin (2-4%), and higher levels of total N (3.5-5%) than stems (total soluble carbohydrates l0-22%, cellulose 2535%, lignin 4-11% and total N 1.5-4%). During the season, leaves did not change much in composition, whereas stems gradually increased in cellulose and lignin. Wintergrowing lucerne stems contained high total N (up to 4%), low, cellulose (13%) and lignin (4%). Irrigation increased soluble carbohydrate in stems, but not leaves in immature luceme. Defoliation of luceme led to a fall in soluble carbohydrate in the standing stems. About 50% of the lucerne total N was easily extracted from the plant as protein. On a kg/ha basis, a yield of 15, 232 kg of DM (non-irrigated) contained 480 kg of total N, 1,385 kg total soluble carbohydrate and 2,563 kg of cellulose. Over a 70-day summer period, a protein yield of over a metric ton/ha was extracted from irrigated lucerne.