Individual study: The effects of rhizome planting orientation and depth on the growth of marram grasss Ammophila arenaria transplants: a glasshouse experiment, Aberdeen University, Aberdeenshire, Scotland
Hobbs R.J., Gimingham C.H. & Band W.T. (1983) The effects of planting technique on the growth of Ammophila arenaria (L.) Link and Lymus arenarius (L.) Hochst. Journal of Applied Ecology, 20, 659-672
Planting of vegetative parts of dune grasses such as marram Ammophila arenaria and lyme-grass Lymus arenarius, has been practiced for many years to stabilize sand and encourage dune formation. In this study, a series of experiments were conducted to test the effects of different planting factors on the growth of rhizomes of these two sand dune grasses. The experiment reported here describes results of a glass house study looking at the effect of rhizome planting orientation and depth on the growth of marram transplants.
Marram collection: Marram planting material was collected on 7 April 1981 from Foveran Links (National Grid ref. NK 000233), 15 km N of the city of Aberdeen, north-east Scotland. Material was as uniform as possible comprising a rhizome segment 10 cm in length with a healthy above-ground tiller system. The marram was placed in moist sand in polythene bags for transport and planted the following day.
Experimental design and planting: A 2 x 3 factorial experiment was established, with two rhizome orientations (horizontal or vertical) and two planting depths (10 cm; 20 cm) with the apical growing point at the sand surface. A smaller 'rhizome only' experiment was established to test the potential for regrowth of marram rhizome segments from which the aerial portion and rhizome apex had been removed, leaving the 10 cm rhizome segment immediately below the apex. Orientation was horizontal or vertical, with the growing point at the surface or at 10 cm depth.
The rhizomes were planted in black polythene pots filled with locally-collected, washed beach sand. The pots were 23 cm in diameter and depth. For 20 cm depth plantings, pots were extended using a polythene collar giving an depth of about 35 cm. Each pot contained two transplants. Further offsets were planted so that weekly development also could be monitored. In all treatments green shoot material was above the sand surface. The 'rhizome only' treatments had 10 plants per treatment. Pots were placed in an unheated greenhouse under ambient light conditions at Aberdeen University Botany Department. These were watered with 50 ml of water immediately after planting, followed by 50 ml of nutrient solution the next day. Subsequently each received 30 ml water twice a week, and 30 ml nutrient solution once a week.
Analysis of plant material: An initial excavation of 10 plants per treatment from the main marram experiment was carried out 9 weeks after the start of the experiment, and the final excavation after15 weeks. The 'rhizome only' treatments were excavated after 15 weeks. Each plant was washed and dead leaf sheath material was removed so that rhizome and bud development could be followed.
The main experiment showed that vertical plantings produced several vertical rhizomes per plant, but no horizontal ones. Average rhizome numbers were slightly higher in the 10 cm plantings. In horizontal plantings, several horizontal rhizomes were produced by most plants, with a smaller number of vertical rhizomes. Numbers of vertical rhizomes were greater at 10 cm planting depth. The number of vertical rhizomes decreased in the deeper planted treatments, but the overall length of new rhizomes increased. Increased planting depth also resulted in significantly less shoots, leaves and roots. Rhizome orientation had no effect on shoot, leaf or root number, but shoots formed tussocks in the vertical treatments and were more dispersed in the horizontally-planted rhizomes. Plant death only occurred in a few 20 cm depth plantings.
The 'rhizome only' treatments indicated that the main factor influencing growth was planting depth rather than orientation. The differences in orientation of new rhizome growth found in the main experiment were not evident, and virtually no horizontal rhizomes were produced in any treatment. There was a decrease in numbers of shoots and leaves with planting depth and a corresponding increase in vertical rhizome lengths, as in the main experiment. There was relatively high mortality (30-40%) except in the horizontal shallow plantings.
Conclusions: Planting the rhizome horizontally enhanced horizontal rhizome development and more rapid vegetation cover than planting vertically. Numbers of shoots and leaves were similar in the horizontal and vertical treatments, but vertical plantings produced a tussocky appearance whereas horizontal plantings gave rise to a similar number of tillers strung out in a linear fashion. Rhizome lengths increased with depth of planting although rhizome numbers decreased. Removal at planting of the tillers and rhizome apex reduced shoot production and increased mortality.
Note: The compilation and addition of this summary was funded by the Journal of Applied Ecology (BES). If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://links.jstor.org/sici?sici=0021-8901%28198308%2920%3A2%3C659%3ATEOPTO%3E2.0.CO%3B2-J