A field experiment was carried in a Factorial Randomized Block Design (FRBD) with three replications, comprising of 12 treatment combinations. The results indicated that the important growth characters were significantly influenced by pinching and application of growth retardants than spacing  tried under this investigation. The treatment combination S2P1G1 i.e., T11 was found to be superior and  recorded more number of flower spikes per plant (11.13) at 75 DAT, maximum length of spike (21.48 cm), maximum florets per spike (82.40), maximum length of florets (1.90cm) and maximum flowering duration (97.06 days). The treatment combination S2P1G1 i.e., T11 (25 cm × 25 cm spacing + pinching + CCC@500ppm) was found to be superior for flowering characters in salvia.

Pinching, spacing, growth regulators, MH, cycocel, spike, flowering.

Salvia splendens L. comes in a variety of hues, including white, salmon, pink, purple, lavender, burgundy, and orange, however the scarlet varieties are highly popular. Salvia splendens L. attains a height of 18" to 30". This genus belongs to the family "Lamiaceae". Salvia  splendens L. is a popular bedding plant used primarily to add a splash of brilliant colour to gardens. It blooms in the winter until spring and it can carry its spikes to the next summer. 

Growth retardants also have influence on the flowering behavior of plants and may result in early flowering or developing more number of flowers per plant, increasing the colour intensity of leaves and bracts (Banon et al., 2001), and also enhances the ability of the plant to tolerate various stress encountered during handling  and shipping (Mackay and Sankhla 2006). 

Spacing influences the compactness of the plants therefore effects the growth and flowering whereas pinching induces more number of lateral branches and results in increased number of flowers.

Besides, the cultural practices followed in bedding plant salvia, use of growth retardants is recommended to get quality crop with high yield by reducing the height and increasing the compactness. 

Thus, present  study is to study the effect of spacing, pinching and growth retardants on flowering and longevity of spikes     on the salvia plants.

The experiment was conducted in the garden of Department of Floriculture and Landscaping, College of Agriculture, OUAT, Bhubaneswar from December 2021 to April 2022. One month old seedlings of salvia were used    as planting material and transplanted into main field as per the treatment. The seedlings were procured from near by    nursery in Bhubaneswar.

Design of experiment: The experimental design followed was Factorial Randomized Block Design (FRBD) with three replications, comprising of 12 treatment combinations which include first factor spacing with two levels i.e., S1 (20 cm × 25 cm) and   S2 (25 cm × 25 cm), second factor pinching with two levels i.e., P0 (no pinching) and P1 (pinching) and  third factor application of growth retardants with three levels i.e., G0 (control), G1(CCC @500ppm) and G2(MH @100ppm).

Preparation of experimental plot: The land was brought to fine tilth and the experimental plots were laid out with a dimension of 1m × 1m, a path of 30 cm width between two plots was created for formation of bunds and carrying out cultural operations.

Four weeks old healthy, uniform and well rooted seedlings were transplanted in the experimental unit according to the spacing viz., of  20 cm × 25 cm and 25 cm × 25 cm, within the row and in between the plants  respectively was followed according to treatment combinations. Pinching was done 25 days after transplanting i.e., immediately after flower bud initiation.

The roots of the seedlings were thoroughly washed with clean water and immersed in the solutions of the growth retardants cycocel and maleic hydrazide and kept for 2 hours for proper absorption. 
Observations recorded: In each treatment, five plants were selected at random and labelled in order to record the observations on floral parameters using a non-destructive process at 15 days interval, starting from 30 DAT  i.e., at 30, 45, 60, 75 days after transplanting.

Number of days taken to visible flower bud initiation (days): The number of days taken from the date of transplanting to the date of appearance of first flower bud was counted and considered as number of days taken to emergence of first flower bud.

Number of flower spikes per plant: Total number of spikes per plant was counted and recorded.
Length of spikes (cm): Spikes length was measured with the help of centimetre scale.
Duration of flowering (days): This was recorded by counting the number of days from initial day of flowering to 100% of the plants in a plot which showed flowering.
Statistical analysis: Statistical significance was tested with  F value at 5% level of probability.

 Treatment combinations:

Number of days taken to visible flower bud initiation (days): From the perusal of data in Table 1, the treatments levels of spacing did not exhibited significant difference. Significant differences were found among the treatments of pinching with regard to number of days taken to visible flower bud initiation. The pinched plants, P1 (27.32) had taken more number of days to initiate flower bud over the plants which were not pinched P0 (22.45). Application of growth retardants at different levels showed significant influence on number of days taken to visible flower bud initiation. The treatment MH G2 had taken more number of days to initiate flowering as compared to CCC G1 (23.70) over the control G0 (22.55). The interactions between S × P, S × G, P × G, S × P × G was found non-significant and were statistically similar.
Table 1: Effect of spacing, pinching and growth retardants and their interaction on number of days taken to visible flower bud initiation (days) in Salvia splendens L.

Number of flower spikes per plant at 60 DAT:  From the perusal of data presented in Table 2, significant difference was observed among the different levels of spacing. The treatment S2 (7.03) recorded more number of flower spikes per plant than S1 (5.73). Pinching also revealed significant results where pinched plants P1 (7.08) produced more number of flower spikes per plant than plants which were not pinched P0 (5.68). The treatments of growth retardants did not exhibit any significant results. However, the interactions between S × P, S × G, P × G, S × P × G was also found to be non-significant.

Number of flower spikes per plant at 75 DAT: From data presented in Table 3, significant difference was observed among the different levels of spacing. The treatment S2 (8.45) recorded more number of flower spikes per plant than S1 (7.33) which were not at statistically par with each other. Pinching also   revealed significant results where pinched plants P1 (8.66) produced more number of flower spikes per plant than plants which were not pinched P0 (7.12). The treatments of growth retardants also exhibited significant results where the treatment CCC G1 (8.72) produced more  number of flower spikes over control G0 (7.25).

However, the interactions between S × P and S × P × G was found to be non-significant. But the interactions between S × G and P × G were statistically significant where more number of flower spikes were produced in treatment S2G1 (9.80), P1G1 (10.05) respectively and least number of flower spikes per plant were produced in treatment S1G0 (6.06), P0G0 (6.70) respectively.

Number of flower spikes per plant at 90 DAT: Data presented in Table 4, significant difference was observed among the different levels of spacing. The treatment S2 (5.91) recorded almost same number of flower spikes per plant as S1 (5.36). Pinching also revealed significant results where pinched plants P1 (6.12) produced more number of flower spikes per plant than plants which were not pinched P0 (5.14). 

The treatments of growth retardants are also significantly different from each other where the treatment CCC G1 (6.00) produced more number of flower spikes over control G0 (5.22). However, the interactions between S × P, S × G, P × G, S × P × G were found to be non-significant.

Length of the spike (cm): From the data presented in Table 5, there was no significant difference among the different levels of spacing. Significant difference was observed among pinching levels where P1 (18.36 cm) recorded maximum spike length than P0 (17.05cm). However, the treatments of growth retardants are also significantly different from each other where the treatment CCC G1 (19.79cm) maximum spike length over MH G2 (16.01cm) and control G0 (17.30cm). The interactions between S × P, S × G and P × G and S × P × G were found to be non-significant.

Flowering duration (days): From the perusal of data presented in Table 6, there is no significant difference among the different levels of spacing. Pinching revealed significant results where the treatment  P1 (86.91) has recorded increased flowering duration which was at par with P0 (85.25).

However, the treatments of growth retardants are also significantly different from each other where the treatment CCC G1 (92.24) recorded increased flowering duration as compared to MH G2 (84.97) and control G0 (81.03).

The interactions between S × P and S × P × G were found to be non-significant and did not differ statistically from each other. However, the interaction between S × G and P × G was found to be significant and the treatment S0G0 (80.76), P0G0 (80.80) recorded minimum duration of flowering respectively whereas S2G1 (94.66), P1G1 (94.68) recorded maximum duration of flowering respectively.

Table 2: Effect of spacing, pinching and growth retardants and their interaction on number of flower spikes per plant at 60 DAT in Salvia splendens L.

Table 3: Effect of spacing, pinching and growth retardants and their interaction on number of flower spikes per plant at 75 DAT in Salvia splendens L.

Table 4: Effect of spacing, pinching and growth retardants and their interaction on    number of flower spikes per plant at 90 DAT in Salvia splendens L.

Table 5: Effect of spacing, pinching and growth retardants and their interaction on length of the spike (cm) in Salvia splendens L.

Table 6: Effect of spacing, pinching and growth retardants and their interaction on flowering duration in Salvia splendens L.

The floral parameter days to visible flower bud initiation was recorded and it was found  to be non-significant for spacing but revealed significant results for pinching and application of growth retardants. The plants which were pinched P1 (27.32) had taken more days to bud initiation than non-pinched plants i.e., P0 (22.45 days). Pinching took more days to bud initiation which might be due to breaking of apical dominance leading to prolonged vegetative  growth and resulted in delayed onset of reproductive phase. These results were in accordance  with the findings of Akshay et al. (2020) in chrysanthemum and Ashvini et al. (2020) in china aster. Among growth retardants early flower bud initiation was observed in control G0 (22.55)   which was at par with CCC i.e., G1 (23.70).

Delayed bud initiation was recorded in MH i.e., G2 (28.70 days). This delay in appearance of first flower bud might also due to action of growth       retardant which by virtue suppress the activities of GA, which is a growth regulator effective in bud initiation. The current results were also supported by findings of Taksande et al. (2017)  in chrysanthemum and Chikte et al. (2017) in marigold.

The flowering parameter number of spikes per plant was recorded at 60, 75 and 90 DAT. The factor spacing and pinching was found to be significant at all the three intervals. The application of growth retardants was found to be non-significant initially but later revealed  significant results. It was evident from the data that maximum flower spikes were recorded at 75 DAT and were significantly different. It was clear that wider spacing S2 (8.45), pinched treatment P1 (8.66) and application of growth retardant CCC recorded more number of flower spikes per plant i.e., G1 (8.72). The interactions were found be non-significant at all the intervals except for S × G and P × G at 75 DAT. This increase in number of flower spikes due  to pinching might be because of restriction of terminal growth, resulting in production of more  lateral branches which might have led to lateral bud initiation from where flowers originate thereby producing more number of flower spikes per plant as reported by Subhendu et al. (2021) in chrysanthemum and Singh et al. (2019) in marigold. Likewise, the increase in flowers  per plant by application of growth retardants might be correlated with the vegetative growth characters like number of branches and number of leaves where the treatment exhibited significant effect. As a result of this the plant had a comparatively higher level of organic reserves conducive for better floral development and thereby increased the number of flower spikes per plant. These findings were corroborated with the results of Sasikumar et al. (2015) in marigold and Jagdale et al. (2017) in chrysanthemum.

The character length of the spike was recorded. Significant differences were  noticed for pinching and application of growth retardants. The factor spacing and the interactions between the factors were found to be non-significant. Maximum length of spike was recorded for S2 (18.26cm) and G1 (19.79cm) and the lowest in MH i.e., G2 (16.01cm) over control i.e., G0 (17.30cm). This increase in spike length might be due to better availability of carbohydrates and other nutrients for floral development.

The parameter flowering duration was found to be significant for pinching and growth retardants but no significant difference was observed for spacing. The interactions were also found to be non-significant except for S × G and P × G. The maximum flowering duration was recorded for P1 (86.91 days) and G1 (92.24 days) for pinching and application of growth retardants respectively. This might be due to delayed flower bud initiation which might have made the treated plants more sturdy and fresh for longer duration and this might have assisted the supply of flower inducing hormones for longer period and might have increased the duration of flowering as reported by Singh et al. (2019) in marigold and Ashvini et al. (2020) in china aster.

Effect of different levels of pinching in salvia should be further standardized. Effect of different level of various growth retardants can also be studied.

Kaberi Maharana, Srilakshmi B.D.V.V.N., N. Amrutha Pavani and Lilymoony Tripathy  (2024). Effect of Spacing, Pinching and Growth Retardants on Flowering of Salvia (Salvia splendens L.). Biological Forum – An International Journal, 16(2): 134-139.