Shoot and Root Growth of Austrian Pine and Norway Spruce Seedlings in Mini-Containers

Abstract

Austrian pine (Pinus nigra Arnold) and Norway spruce [Picea abies (L.) Karst.] were seeded in Jiffy Mix in selected mini-containers and grown for 18 weeks in a greenhouse with average day and night temperatures of 300 and 18'C, respectively. The stem length of both species was greatest in Book Tinus; intermediate in Book Hillson, Square Bottomless Container and Tar Paper; and smallest in Leach Tube, Styroblock 8, and Styroblock 7. The shoot and root dry weights and root quality of Austrian pine seedlings were similar in all containers tested. Norway spruce seedlings had greater total root or shoot dry weight and root quality in the smaller containers (Styroblock 7, Styroblock 8, and Leach Tube). The root dry weight/container volume ratio (mg/cm3) of both species was smaller in the larger containers (Book Hillson, Book Tinus, and Square Bottomless). In recent years, the nursery industry has gradually shifted from field-grown, bare-root nursery stock to container production. The increased use of containerized seedlings in nursery and forestry production results from advantages of better plant survival and growth, extension of the planting season, and adaptability to mechanical planting. Generally, there are three categories of containers used in forestry and ornamental plant production: tube, block, and plug (Barnett, 1982). A containerized seedling has a root system that holds the growing medium when removed from the container and, upon planting makes, immediate contact with the soil. Easy plug extraction depends upon the proper development of the root system, media, moisture content of the plug and construction of the container walls and ridges (Tinus, 1978). Design and shape of nursery containers have recently been improved. Contribution No. 89-90-J from the Kansas Agricultural Experiment Station. 2 Associate Professor of Horticulture. 3 Present address: King Saud University, Riyad, Saudi Arabia. This content downloaded from 207.46.13.113 on Thu, 06 Oct 2016 04:16:19 UTC All use subject to http://about.jstor.org/terms 18 TRANSACTIONS OF THE KANSAS ACADEMY OF SCIENCE Table 1. Container/cavity dimensions. Top diam. Length Width Depth Volume Container type Composition Class. (cm) (cm) (cm) (cm) (cm3) Styroblock 7 Styrofoam Small 3.0 22.5 121.3 Styroblock 8 Styrofoam Small 3.8 15.0 131.1 Leach Tube Polyethylene Small 3.8 13.5 131.1 Book Hillson Polyethylene Large 3 8 12.5 3.8 12.5 172.1 Square Bottomless Plastic Large 4.0 19.0 4.0 18.9 302.4 Book Tinus Polyethylene Large 5.0 18.1 3.8 18.1 352.4 Cylinder Tar Paper Asphalt Large 6.2 20.0 6.5 18.9 570.8 Some mini-containers now have vertical ribs or grooves along their walls and drainage holes at the bottom. The ribs are intended to direct the roots downward and, therefore, prevent circling of roots (Dickenson and Whitcomb, 1978; Tinus and McDonald, 1979). Research has shown that container volume and diameter influence plant growth, and there is a minimum volume below which growth is limited (Wall and Whitcomb, 1980). The shoot and root growth of Pinus caribaea var. hondurensis was influenced by the cavity sizes of Styroblock 4 and 8 (Venator and Rodriguez, 1977). Similar results were noted for Pinus contorta and Picea glauca (Carlson and Endean, 1976; Endean and Carlson, 1975). Seedlings produced in uniform sized mini-containers are adaptable to mechanized planting. The production cost may be higher for containerized seedlings than for field-grown ones, but compensations include faster and superior growth, increased production, longer planting periods, and lower labor and land costs. The purpose of this study was to evaluate the effectiveness of selected mini-containers on shoot and root growth of Austrian pine and Norway spruce seedlings. MATERIALS AND METHODS Four seeds of Austrian pine (Pinus nigra Arnold) and Norway spruce [Picea abies (L.) Karst.] were sown in each cavity of selected mini-containers filled with Jiffy-Mix [commercially available sphagnum peatmoss-vermiculite 1:1 (v) mix] and placed on wire benches in a glass greenhouse. The containers consisted of Styroblock 7 and 8 (Silvaseed Company, Roy, Washington); Leach Tube (Ray Leach Cone-Tainer, Canby, Oregon); Book Hillson and Book Tinus (Spencer-Lemaire Industries Ltd., Edmonton, Canada); Square Bottomless (Jack Russell, DeSoto, Kansas); and Cylinder Tar Paper (hand made) (Table 1). Two weeks after germination, seedlings were thinned to one per cavity. After 3 weeks of growth, seedlings were fertilized with water soluble 20N-8.6P-16.6K (20-20-20) to provide 100 ppm N with each waterThis content downloaded from 207.46.13.113 on Thu, 06 Oct 2016 04:16:19 UTC All use subject to http://about.jstor.org/terms VOLUME 93, NUMBERS 1-2 19 ing. The pH of the water was maintained between 5.0-5.5 using phosphoric acid (Tinus and McDonald, 1979). The pH and electrical conductivity (EC) of the growing medium were monitored before and throughout the trial. The containerized seedlings were grown for 18 weeks from March to August with an average day/night temperature of 300 and 180C, respectively. The development of the root system in each container was visually evaluated. The plants were harvested, and roots were dried separately at 650C for 72 hours and weighed. The experimental design was a split-plot in a randomized block with seven containers and two species replicated four times. Growth measurements were determined by randomly selecting six samples of each container and species. RESULTS AND DISCUSSION Stem length. Austrian pine and Norway spruce seedlings in the larger containers such as Book Hillson, Book Tinus and Cylinder Tar Paper had greater stem length as compared to those in the smaller cavities of Styroblock 7 (Table 2). The larger volume of these containers (Table 1) may have influenced plant stem length. Similar results have been reported by others (Carlson and Endean, 1976; Endean and Carlson, 1975). Shoot and root dry weight. Shoot dry weight of Austrian pine was similar in all containers tested (Table 2). Austrian pine grown in Cylinder Tar Paper had the lowest root dry weight in comparison to Styroblock 8, Book Tinus, and Square Bottomless. The greatest shoot dry weight for Norway spruce was obtained in Styroblock 7 and Styroblock 8, when compared to Book Hillson and Book Tinus. Similarly, spruce grown in Styroblock 7, Styroblock 8 and Leach Tube had the highest root dry weight compared to Book Hillson and Book Tinus. Endean and Carlson (1975) reported that container configuration (height or diameter) had no effect on shoot dry weight or shoot length of Lodgepole pine seedlings, but did affect white spruce seedling growth. Spruce is more shallowly rooted than pine, with a greater number of roots in the top quarter of the container. The Austrian pine had more roots in the bottom of the container and grew equally well in all containers tested. Shoot/root ratio. The shoot/root dry weight ratio of Austrian pine seedlings was greatest in the Cylinder Tar Paper container, which produced the smallest root system (Table 2). Norway spruce had a greater shoot/root dry weight ratio in several larger volume containers, such as Book Hillson, Book Tinus, and Cylinder Tar Paper (Table 2). Root quality. The extensiveness, fibrousness, and uniformity of the root system were taken into consideration when visual evaluations of root quality were made. With the exception of Cylinder Tar Paper container, the root system of Austrian pine was found to be very good in all containers tested (Table 2). Norway Spruce produced a good root system in Leach Tube, This content downloaded from 207.46.13.113 on Thu, 06 Oct 2016 04:16:19 UTC All use subject to http://about.jstor.org/terms 20 TRANSACTIONS OF THE KANSAS ACADEMY OF SCIENCE Table 2. Effect of various containers on stem length (cm), dry weight (g), root quality and root dry weight/container volume ratio (mg/cm') of Austrian pine and Norway spruce seedlings, 18 weeks after germination.