Changes in alfalfa cell wall structure during vegetation

Abstract

The investigation was done on 141 samples of one alfalfa cultivar, collected from the same location during the first three growth cycles: spring growth, the first and the second regrowth. Within each growth cycle, sampling was done during the whole growing period, commencing when plant height was below 150 mm and continuing until plants were bearing ripe seeds. On all collected samples the following cell wall characteristics were determined: neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), neutral detergent insoluble crude protein (NDICP), acid detergent insoluble crude protein (ADICP). Cellulose and hemicellulose were detected on the base of the mentioned chemical parameters. Significantly lower (p lt 0.01) content of aNDF, ADF, ADL, ADICP and cellulose is found in the second regrowth, while there were no significant differences between the other two growth cycles. Except in NDICP and ADICP, the increase in all accompanying components of the cell wall was observed, and expressed in average daily changes. There was no consistent trend in NDICP and ADICP. During the spring growth from late bud to full-bloom stage the 'plateau' was observed. The plateau was represented as almost constant content of aNDF, ADF, ADL and cellulose. The correlations between all components of the cell wall were shown. The equation aNDF = 36.713 + 1.181 × ADF is recommended for conversion of ADF into aNDF in alfalfa.

Istraživanje je sprovedeno na 141 uzorku iste sorte lucerke, sakupljene na istoj lokaciji tokom prva tri ciklusa vegetacije: prolećni ciklus, drugi ciklus i treći ciklus. Tokom svakog ciklusa, uzorkovanjem je obuhvaćen ceo ciklus vegetacije, od momenta kada su biljke imale visinu manju od 150 mm sve do momenta kada su biljke imale zrelo seme. U svim sakupljenim uzorcima određeni su sledeći parametri ćelijskog zida: vlakna nerastvorljiva u neutralnom deterdžentu (aNDF), vlakna nerastvorljiva u kiselom deterdžentu (ADF), lignin (ADL), protein nerastvorljiv u neutralnom deterdžentu (NDICP), protein nerastvorljiv u kiselom deterdžentu (ADICP). Celuloza i hemiceluloza su određene na osnovu navedenih hemijskih parametara. Utvrđena je značajno manja (p lt 0.01) količina aNDF, ADF, ADL, ADICP i celuloze u trećem ciklusu vegetacije, dok između ostala dva ciklusa nisu utvrđene veće razlike. Izuzev kod NDICP i ADICP, utvrđen je porast svih praćenih komponenata ćelijskog zida i izražen u prosečnim dnevnim promenama. Kod NDICP i ADICP je zabeleženo odsustvo trenda. Tokom prolećnog ciklusa od faze punog pupoljenja do faze punog cvetanja je zabeležen 'plato', odnosno skoro konstantna količina aNDF, ADF, ADL i celuloze. Prikazane su korelacije između svih parametara ćelijskog zida. Jednačina aNDF = 36.713 + 1.181 × ADF je preporučena za konverziju ADF u aNDF u lucerki.