Growth and Physiological Characteristics of Sour Jujube Seedlings in Different Substrate Formulations

Abstract

The raising of container seedlings with light substrates has become an important method of seedling raising, without delaying the seedling period. In order to reduce reliance on non-renewable peat and to promote the reuse of organic waste, this study compared the growth of sour jujube seedlings in different substrate formulations (i.e., different proportions of vermicompost instead of peat), using a semi-subterranean placement of root control bags, and explored the application of vermicompost in the raising of sour jujube seedlings. The results showed that there were significant differences in the growth and the physiological and photosynthetic characteristics of sour jujube seedlings treated with different substrates, among which substrates A2 (peat: vermicompost: vermiculite: garden soil = 0.5:0.5:1:1) and A3 (peat: vermiculite: garden soil = 1:2:1) were suitable for sour jujube seedling raising. The seedling height, the seedling ground diameter, the number of secondary branches, the length of the longest secondary branch, the total fresh weight, the aboveground fresh weight, the total root length, the root projection area, and the root surface area were all significantly greater than those of jujube seedlings grown on other substrates. Especially in A3, vermicompost can replace peat as the nursery substrate for sour jujube seedlings, removing dependence on non-renewable peat resources, reducing costs, and providing more prospects for application. The suitable substrate conditions for sour jujube seedlings were as follows: soil porosity 44.0–54.0%, electric conductivity (EC) value 0.2 mS/cm, organic matter 40.39~54.05 g·kg−1, total nitrogen and total phosphorus of 1.67~1.91 g·kg−1 and 0.95~1.20 g·kg−1, respectively, alkali-hydrolyzed nitrogen 139.75~154.69 mg·kg−1, and available phosphorus 137~224 mg·kg−1.