Introduction
Cooper's haworthia (Haworthia cooperi), a succulent native to South Africa, is distinguished by its small, fleshy, and semi-transparent leaves forming a rosette shape. This plant is well-regarded among succulent enthusiasts for its attractive appearance and relatively easy-care requirements. The primary aim of this study was to investigate the growth response of cooper's haworthia under in vivo cultivation conditions following in vitro cultivation. In vitro propagation techniques offer a controlled environment to initiate growth, but transitioning plants to in vivo conditions is critical for their survival and subsequent development. Understanding the effects of different substrates and irrigation methods on this transition is essential for optimizing cultivation practices for cooper's haworthia and potentially other succulent species.
Materials and Methods
The experiment was designed as a factorial study, implemented using a completely randomized design with five replications to ensure the reliability and validity of the results. The initial propagation of plant samples was conducted in Murashige and Skoog (MS) medium, supplemented with 3 mg l^-1 benzyladenine (BA) and 0.5 mg l^-1 naphthaleneacetic acid (NAA) to encourage robust shoot formation. Rooting was achieved in half-strength MS medium containing 1 mg l^-1 indole-3-acetic acid (IAA), providing an optimal balance of nutrients and growth regulators for root development.
Following successful acclimatization in a greenhouse setting, the plants were subjected to various substrates and irrigation levels to assess their effects on growth and physiological characteristics. The substrates tested included peat moss-perlite, cocopeat-perlite, and a mixture of sand-vermicompost-perlite. These substrates were selected for their differing properties in terms of aeration, moisture retention, and nutrient availability. Irrigation treatments included saturated, semi-saturated, and dry conditions to mimic different moisture availability scenarios.
Results and Discussion
The results demonstrated that the cocopeat substrate under dry irrigation conditions provided the best overall growth performance. Plants cultivated in this medium exhibited the highest fresh shoot weight, dry leaf weight, shoot volume, and shoot surface area compared with the other treatments. In addition, these plants showed increased concentrations of carotenoids and chlorophyll a, indicating enhanced photosynthetic capacity and improved physiological status. Fresh and dry root weights were also significantly higher in the cocopeat substrate, highlighting its effectiveness in promoting both shoot and root development. In contrast, the peat moss substrate showed superior performance under semi-saturated irrigation conditions by producing the highest number of leaves. This finding suggests that peat moss may offer a favorable balance between moisture retention and root aeration, thereby supporting enhanced leaf proliferation. Furthermore, saturated irrigation conditions in the peat moss substrate led to the highest chlorophyll b content, indicating a positive response of the plant's photosynthetic machinery to high moisture levels. Conversely, the mixed substrate of sand-vermicompost-perlite demonstrated the lowest performance under dry irrigation conditions. Plants in this treatment had the lowest fresh shoot weight, dry leaf weight, shoot volume, and shoot surface area, likely due to poor aeration and limited oxygen availability. These conditions are less conducive to the growth of cooper's haworthia, highlighting the importance of selecting appropriate substrates that ensure adequate aeration and moisture retention. The superior performance of cocopeat under dry irrigation conditions can be attributed to its high moisture-retaining capacity and nutrient availability. These properties are crucial for the growth and development of succulent plants, which typically thrive in well-drained yet moisture-retentive substrates. The findings also highlighted the significant role of irrigation methods in influencing plant growth. Optimal irrigation practices can prevent issues such as root rot and improve water use efficiency, further enhancing plant health and productivity.
Conclusion
This study demonstrates the critical impact of substrate and irrigation method on the growth and physiological characteristics of cooper's haworthia. The results suggest that cocopeat, due to its excellent moisture retention and nutrient provision capabilities, is the most suitable substrate for the optimal growth of this succulent. Additionally, adopting appropriate irrigation methods can significantly enhance plant performance and health. These findings have broader implications for horticultural practices, offering valuable insights for the cultivation of other succulent species. By selecting the right combination of substrate and irrigation, growers can ensure the successful adaptation and thriving of cooper's haworthia plants, paving the way for improved horticultural outcomes.