Germination, vegetative and flowering behavior of Balsam (Impatiens balsamina L.) in response to natural photoperiods

A lack of application of photoperiod and light intensity to manipulate the growth of current spring annuals has, in part, been due to the lack of information identifying the photoperiodic and light intensities requirements of various species. Present pot experiment was carried out at Horticulture Garden, Department of Horticulture, Sindh Agriculture University Tandojam, during spring 2017, which was laid out in a three replicated Complete Randomized Design (CRD). Two varieties of balsam (V1= Tom Thumb, V2 = Double Camcellia) were studied under NP1= Control (Normal day length), NP2=3 hrs (8:00 am- 11:00 am), NP3= 6 hrs (8:00 am – 2:00 pm), NP4= 9 hrs (8:00 am-5:00 pm), NP5= Natural shade. Results from the research data revealed significant (P


INTRODUCTION
Balsam, (Impatiens balsamina L.) is an ornamental plant in the Balsaminaceae family (Gardeners, 2017). It is a quick growing summer annual flower, with gardenia-like blooms (Tooke and Battey, 2000). Continuous blooms grow on top of a bushy plant with leaves. The balsam is originated in Asia, North America and South Africa and there are numerous annual and perennial varieties (Christopher, 2013). The blooms appear in about 60-70 days and colours include shades of white, pink, rose, violet, and red (Park et al., 2003;Wang et al., 2009). Different parts of the plant are used as traditional remedies for disease and skin afflictions. Juice from the leaves is used to treat warts and snakebite, and the flower is applied to burns (Wang et al., 2009). This species has been used as indigenous traditional medicine in Asia for rheumatism, fractures, and other ailments (Park et al., 2003). Changes in temperature and day-length trigger physiological and seasonal developmental processes of ornamental plants that enable ornamental plants withstand severe climatic conditions (Adams et al. 2005). Climate change is expected to increase the air temperature in the summer, while the natural decreasing photoperiod remains unaffected (Kim et al., 2009). As shown previously, an increase in air temperature inhibits CO2 assimilation, with a concomitant increased capacity for zeaxanthin-independent dissipation of energy exceeding the photochemical capacity of plants (Busch et al.,2008). Flowering behaviour in plant cycle shows the adaptability of plants to seasonal changes (Kim et al., 2009) and increase in duration of photoperiod reduced time to first visible bud. Temperature and day length are related in the sense that as the natural day length becomes longer or shorter, the temperature warms or cools, respectively (Ha, 2014).
A lack of application of photoperiod and light intensity to manipulate the growth of current spring annuals has, in part, been due to the lack of information identifying the photoperiodic and light intensities requirements of various species. The proposed study is mainly aimed at examining the effect photoperiod on germination of vegetative and flowering traits Balsam (Impatiens balsamina L) under light intensity.

II.
MATERIALS AND METHODS Present study was conducted during summer, 2017 at Horticulture Garden, Department of Horticulture, Sindh Agriculture University, Tandojam. Seed of two balsam verities (V1= Tom Thumb, V2 = Double Camellia) were sown in 20-cm diameter earthen pots in late February 2017 using a silt FYM-based medium in a 1:1 ratio based on volume. Potted seed of both balsam varieties were germinated with five natural photoperiod treatments resulted from the installation of black shade cloth. For control treatment pots were simply kept under normal day length in sun light, while pots of both varieties were kept under shade for normal day length, while for other photoperiod pots were covered with black cloth and uncovered as per photoperiod hours. Such a design has been used to exclude any direct illumination and to obviate any microclimate alterations due to the presence of the shade cloth. A two factor (Factor -A: Varieties (V) = 02 (V1 = Tom Thumb, V2 = Double Camellia); Factor-B: Natural Photoperiods (NP) = 04 (NP1= Control (Normal day length= 12 hrs= 6 am to 6 pm), NP2=3 hrs (8:00 am-11:00 am), NP3= 6 hrs (8:00 am -2:00 pm), NP4= 9 hrs (8:00 am-5:00 pm), NP5= Natural shade) Completely Randomized Design (CRD); was set out with three replications where each replication was had four pots. Frame structure was made by placing wooden pegs of about 4 ft in height from ground length on both side of the plant row than a black thick cloth was covered leaving 3 inches from the ground surface for aeration, where plants were observed for seed Germination (%), germination index (GI), plant height (cm), leaves plant -1 , days to 1 st flower, flowers plant -1 , days to flower persistence, weight of single flower (g), chlorophyll content (SPAD).

Procedure of recording observations
Seed Germination (% ): Germination percentage was calculated as per following formula. Total number of seeds was sown and at seventh day germinated seedlings were calculated from each treatment than were divided with total number of seeds sown which were multiplied by 100 as per follows: GP = Seeds germinated / Total No. of seed x 100

Statistical analysis:
The data was statistically analyzed using Statistix-8.1 computer software (Statistix, 2006). The Deccan's Multiple Range Test was applied to compare treatments superiority in case results are significant at P≤ 0.05 probability level.

Germination index
The results for varieties seed germination index (Fig. 2) revealed that the variety Tom Thumb produced maximum (0.62 GI) germination index as compared to Double Camcellia (0.55 GI). Both the varieties responded well when exposed to natural photoperiod from 8:00 am to 5:00 pm. Tom Thumb had maximum germination index (1.30 GI) followed by Double camellia (1.07 GI). However when both varieties were exposed to low photoperiod from 8:00 am to 11:00 am produced less germination index (0.28 GI and 0.22 GI respectively). Results also revealed that the maximum germination index (1.18) was observed from NP4= 9 hrs (8:00 am-5:00 pm) followed by control (12 hrs= 6 am to 6 pm) where plant were grown in full day sunlight (0.66 GI). Further data showed that NP2=3 hrs (8:00 am-11:00 am), NP3= 6 hrs (8:00 am -2:00 pm and NP5= Natural shade had minimum germination index of balsam (0.25, 0.46 and 0.39 GI).   Fig-3 It can be seen from the results that plant height varied significantly (P<0.05) for the treatments and varieties. The results for varieties revealed that the variety "Tom Thumb" produced maximum plant height as compared to "Double Camcellia". Both the varieties responded well when exposed to natural photoperiod from 8:00 am to 5:00 pm. "Tom Thumb" had maximum plant height (20.02 cm) followed by "Double camellia" (14.53 cm) followed by normal day length of 12 hours. However when both varieties were exposed to low photoperiod from 8:00 am to 11:00 am produced less plant height (7.58 and 6.80 cm, respectively) as well as under natural shades their response was also negative.

Leaves plant -1
The data regarding leaves plant -1 as affected by different natural photoperiods on vegetative and flowering behavior of Balsam are presented in the Fig-4   can be seen from the results that leaves plant -1 varied significantly (P<0.05) between the treatments and varieties. Both the varieties responded well when exposed to natural photoperiod from 8:00 am to 5:00 pm. "Tom Thumb" had maximum leaves plant -1 (73.00) followed by "Double camellia" (43.66) followed by normal day length (12 hours) where "Tom Thumb" produced 54.66 leaves where as "Double camellia" produced 41.66 leaves on single plant . However when both varieties were exposed to low photoperiod from 8:00 am to 11:00 am produced less leaves plant -1 (5.33 and 3.16, respectively) followed by plants grown under natural shades 6.33 and 4.0 ("Tom Thumb" and "Double camellia", respectively) .

Flowers plant -1
The data regarding for flowers plant -1 as affected by different natural photoperiods on vegetative and flowering behavior of Balsam are presented in the Fig-5 It can be seen from the results that flowers plant -1 varied significantly (P<0.05) between the treatments and varietal interaction.
The results revealed that both the varieties responded well when exposed to natural photoperiod from 8:00 am to 5:00 pm. Balsam variety "Tom Thumb" had maximum flowers plant -1 (6.16) followed by "Double camellia" (4.66) followed by natural photoperiod of 12 hours where "Tom Thumb" developed 5.66 flowers on single plant and "Double camellia" produced 4.33 flowers on single plant. However when both varieties were exposed to low photoperiod from 8:00 am to 11:00 am produced less flower plant -1 (4.33 and 1. 16  The data (Fig. 6) regarding for days to first flower plant -1 as affected by different natural photoperiods on vegetative and flowering behavior of Balsam presented varied significant (P<0.05) difference between the treatments and varieties. Results revealed that both the varieties responded well in terms of days to 1 st flower appearance when exposed to 09 hours of natural photoperiod from (8:00 am-5:00 pm).
Here the variety "Tom thumb" had produced first flower plant -1 within minimum number of days (34.88) followed by "Double Camelia" (38.21) followed by natural photoperiod of 12 hours where variety "Tom thumb" had developed first flower after 44.71 days followed by "Double Camelia" that had first flower after 47.2 days of sowing. However when both varieties were grown under Natural shade took maximum days to first flower appearance plant -1 for both the varieties (64.33 and 65.16, respectively) followed by 6 hours of photoperiod exposure (8:00 am-11:00 am).

Days to flower persistence
The data regarding for days to flower persistence as affected by different natural photoperiods are presented in the Fig.7  Thumb" had maximum days to flower persistence (12.00) followed by Double camellia (9.33). However when both varieties were exposed to low photoperiod from 8:00 am to 11:00 am aloted less days to flower persistence (3.34 and 2.01, respectively) followed by natural shade (4.66 and 3.04, respectively) for both the varieties of Balsam.

Weight of single flower (g)
The data regarding weight of single flower (g) plant -1 as affected by different natural photoperiods have been presented in the

Chlorophyll content (SPAD)
The results (Fig.9) for both varieties of Balsam revealed that Both the varieties responded well when exposed to natural photoperiod from 8:00 am to 5:00 pm where, "Tom Thumb" had developed maximum chlorophyll content (49.87) followed by "Double camellia" (43.71). These varieties when grown under normal day length (12 hrs) developed chlorophyll content of maximum (37.89) in "Tom Thumb" followed by "Double camellia" (36.04). However when both varieties were exposed to low photoperiod from 8:00 am to 11:00 am produced less chlorophyll content (21.05 and 20.08, respectively) followed by plants grown under shade (24.55 and 20.89, respectively).

IV. DISCUSSION
It is obvious the present results had significant effects on varieties and natural photoperiod and varieties. For obtaining good germination keeping the soil moist is favorable and seeds are sown in early season covering with 1/8" of soil layer and water is given continuous ly to keep the soil moist till the germination is completed. The germination initiation may range between 10-15 days (Li et al., 2011;Hua et al., 2012;Christopher, 2013  Temperature and day length are related in the sense that as the natural day length becomes longer or shorter, the temperature warms or cools, respectively. Tooke and Battey (2000) found that the completion of flower development in Impatiens balsamina requires continuous inductive (short-day) conditions. Plants were grown in long-day (LD) conditions of 8 hr of light provided by tungsten and fluorescent bulbs at 271 to 309 µmol.m -2 sec -1 , followed by 16 hr of tungsten light at 4.2 to 5.2 µmol.m -2 sec -1 . Short-day (SD) conditions were 8 hr of tungsten and fluorescent light (as above) followed by 16 hr of darkness. Kim et al., (2009) indicated that the chemical, biological and physiological process is influenced by temperature. The cut flowers produced during summer when temperature exceeds 38 o C, the biological processes are adversely affected. The leaf number below the 1 st flower was affected by the addition of supplemental lighting with one some species of ornamental plants (Erwin and Warner 2002;Blanchard and Runkle, 2011). Under the conditions of extremely high temperatures, the plant proteins are denatured, affecting these processes and subsequently the flower quality has been adversely affected due to florigen present in flower (Wahocho et al., 2016). Erwin and Warner (2002) cultivated ornamental plants at 16 0 C or 20 0 C in combination with short day (SD, 8 hours) or long day (LD, 16 hours). Time to flower (first horizontal petals) at 16 0 C increased from 56 to 64 days as so increased from 1 week to continuous conditions in SD, while LD decreased time to flower from 64 to56 days. Time to flower at 20 0 C varied from 73 to 87 days with additional SD exposure resulting in flower and LD in faster flowering.

V.
CONCLUSION From present study It is concluded that Balsam variety "Tom Thumb" variety grown under NP4= 9 hrs (8:00am -5:00am) natural photoperiod had significant effect on all the vegetative and flower traits studied. The results also revealed that the decrease in daylight adversely affected the traits investigated and photoperiod treatment comprised of 9 hours (8 am -5:00) severely increased the flowers plant -1 as well as the flower quality. So, Balsam can be successfully grown for commercial purpose under 9 hrs (8:00am -5:00am) of natural photoperiod.