Effect of temperature, soil moisture content and type of cutting on establishment of sweet potato cuttings

Abstract

Effective rooting is essential for successful crop establishment from cuttings. The objective of this study was to determine the effect of temperature and soil water content on the root and shoot growth during the early establishment of sweet potato cuttings. Root growth and development were examined in a phytotron at four temperatures (20, 24, 28 and 32 °C constant) and with four types of cuttings (3 node cutting vertically planted, 3 node cutting planted upside down, 3 node cutting horizontally planted and 1 node cutting planted horizontally). The cuttings were allowed to establish and grow for three weeks. The highest total root length (3.59 m plant-1) was recorded in the 24 °C growth chamber and was significantly longer than the roots from the other temperature treatments. The highest root dry mass (0.22 g plant-1), shoot dry mass (1.7 g plant-1), leaf area (578 cm2) and total dry mass (2.0 g plant-1) were also obtained from the 24 °C growth chamber. The three node cuttings planted vertically produced the longest total root length of 3.66 m plant-1 which was significantly longer than those of the other cutting types. The highest root dry mass, shoot dry mass, leaf area, vine length, leaf number, and total dry mass were also obtained from the vertically planted three node cuttings. To determine the response to soil moisture content, cuttings were sealed and allowed to establish and grow in plastic bags containing sandy soil at 100, 80, 60 and 40% of field water capacity. After 12 and 20 days in a growth chamber at 28 °C the plants were harvested. The 80% of field capacity moisture regime was found to be the optimum soil moisture content for sweet potato root growth. With the soil water content at field capacity and at 40% of field capacity root development was somewhat suppressed. The results illustrated the capacity of sweet potato cuttings to establish successfully under a range of ambient temperatures and soil moisture contents.