Standardisation of Pre Hardening and Hardening Techniques for In vitro Derived Plantlets of Orchid and Anthurium

Orchid

The survival percent was enhanced in T2 followed by control (Table 1).

This may be due to the process of acclimatization of the plant lets to the hardening media in the in vitro condition itself. The transplantation shock was lesser in the hardening media for the prehardened plantlets that the control plants and hence they survived better [1]. The plantlets in this media established well in terms of plant height in laboratory and in shade net (7.15 cm and 33.13 cm) (Table 2) and number of new shootlets (Plantlet (1.78 and 7.4)) at laboratory and shade net condition (Table 1) [2].

Table 2: Effect of prehardening and hardening of media on the plant height and number of roots of in vitro derived plantlets of Orchid variety Sonia-17 However the number of leaves were highest in T5 (5.81 and 26.03) and number of roots i.e., 10.77 and 23.9 /plant were higher in medium containing Charcoal + Brick + Coco peat (1:1:1) i.e., as control and it was closely followed by T2 (Leaf mould + Charcoal + Brick (1:1:1)).

The root and shoot length were recorded higher in T2 (Leaf mould + Charcoal + Brick (1:11:1)) a 6.11 cm and 16.77 cm and 4.48 cm and 20.47 cm in laboratory and in shade net respectively (Table 3).

Epiphytic orchids generally need good aeration this is because in their natural habitat they are tree dwellers with roots hanging in the air. In order to provide paper aeration than the potting mixture must be porous which allows excess water to drain off but at the same time must be able to soak up and the retain moisture without sogging. The better establishment of plantlets in leaf mould + charcoal + brick (1:1:1) followed by charcoal + brick + cocopeat (1:1:1) medium may be due to the maintenance of better micro environment with optimum humidity and aeration compared to the other potting mixtures [3]. The reason for the maintenance of optimum humidity and moisture retention was due to the addition of leaf mould. In the present study the survival and establishment rate remained. Comparatively low in leaf mould + cocopeat + charcoal (1:1:1). However Sharma and Tandon (1992) [4] reported better survival of plantlets of dendrobium sp. In earthen pots containing charcoal + brick pits and coconut fibre (Table 4).

Table 4: Effect of prehardening and hardening of media on root length of in vitro derived plantlets of Orchid variety Sonia – 17. Spraying of ½ MS nutrient solution resulted in better establishment of plantlets. But there was a non-significant interaction between the pot mixture and nutrient solution spray on the establishment of plantlets. The reduced survival of the plantlets during hardening was resulted because of the shock due to the physiological changes during the sudden transition. However the solution of the medium in which the plantlets have been maintained, have minimized the shock and supported the establishment of the plantlets.

Anthurium

The survival percent was enhanced in T2 as 92.43% and 91.53% in laboratory and in shade net followed by control (Table 5).

Table 5: Effect of prehardening and hardening of media on the survival percent and plant height of in vitro derived plantlets of Anthurium variety Temptation. This may be due to the process of acclimatization of the plantlets to the hardening media and addition of NAA of 1 mg/l as the standard one which enhances the better rooting in the in vitro condition itself. The transplantation shock was lesser in the hardening media for the prehardened plantlets that the control plants and hence they survived better [5]. The survival percent was higher in T2 followed by T6. Higher no. of leaves and plant height were observed in T2 followed by T6. Jawaharlal et al. (2001) [6] reported from their studies with hardened in vitro plantlets on standardization of growing media, cocopeat applied alone and in combination with leaf mould and FYM produced the highest number of branches and suckers / plant.

Table 6: Effect of prehardening and hardening of media on number of leaves and number of shootlets of in vitro derived plantlets of Anthurium variety Temptation. The number of leaves were highest in T2 (12.33 and 20.67) Chandrappa (2002) [7] and number of roots i.e., 3.33 and 8.33 / plant were higher in medium containing Leaf mould + Coco peat + Charcoal (1:1:1) followed by control i.e., T6 (Leaf mould + Coco peat (1:1)) (Table 6) [8].

The root length was also recorded higher in T2 (Leaf mould + Coco peat + Charcoal (1:1:1)) as 4.3 cm and 15.67 cm (Table 7) in laboratory and in shade net respectively.