Caladium cv . Florida sweetheart production at different planting depths and sowing dates

Ornamental bulbous crops emergence and yield can be improved by its emergence from soil. The response of Caladium to different planting depths and dates was investigated at Ornamental Horticulture Nursery, Department of Horticulture, The University of Agriculture, Peshawar during the year 2008. Randomized Complete Block Design in a split plot arrangement was used repeated three times. Sowing dates (30th March, 15th April and 30th April) were allotted to main plots whereas planting depths (2.5 cm, 5 cm, 7.5 cm and 10 cm) were kept in sub plots. Findings revealed that Caladium tubers sown on 30th March took maximum days to sprouting (33), produced maximum number of sprouts plant-1 (2.21), gained maximum tuber size (40.88 cm3) with high tuber yield (5397 kg ha-1). On the other hand, tubers sown on 30th April took less days to sprouting (20.21), produced less number of sprouts plant-1(1.53), produced small tuber (33.28 cm3) and total tuber yields was also less (4374 kg ha-1). In case of planting depth, Caladium tubers sown at a depth of 7.5cm resulted in maximum plant height (52 cm), tuber size (41.76 cm3), and tuber yield (5288 kg ha-1) while maximum number of tubers plant-1 (1.92) was observed at a depth of 10 cm. Tubers sown in 2.5 cm depth resulted in minimum tuber yield (4538 kg ha-1) and plant height (46.56 cm). To maximize vegetative as well as tubers production of Caladium cv. Florida sweet heart, it shall be sown on 30th March with 7.5cm depth.


INTRODUCTION
Caladium (Caladium hortulanum) of Family Araceae commonly known as "Angels wing" is a colorful foliage potted plant or out door bedding plant that can be propagated through seed, tubers and tissue culture.Seed production requires long time and results in seedling's variability and limited only to breeding program.Commercially, caladiums are produced through tubers sown in April and harvested from November to February.Tubers are stored at 65-70 o F with preferable temperature of 70 o F at about 75% relative humidity (CONOVER and POOLE, 1973).
New shoots arise from tubers and each tubers may have 1-5 large prominent and numerous small eyes (HARBAUGH et al., 1979).Caladium performs best in a potting medium containing high peat and organic matter V. 24, N o .4, 2018 p. 311-316 with optimum water holding capacity.Tubers perform better when sown at a depth of 5.0-7.5 cm as roots are emerge from the upper side of the tuber with 20-30 cm apart (ALI, 2012).The nursery growers in Pakistan are not adequately familiar with the production technology of Caladium.Thus growers face serious problems including appropriate planting time and suitable planting depth.The currant study was initiated to locate the best planting time and appropriate depth for optimum production of Caladium tubers under agro climatic conditions of Peshawar, Pakistan and also to study the interaction between sowing dates and depths on foliage growth and tubers production.The findings obtained during this study will not only be of academic interest but also of commercial importance.

MATERIALS AND METHODS
Caladium cultivars namely Florida Sweetheart were tested to evaluate the effects of various planting depths and sowing dates on the overall performance of Caladium.Plants were raised through tubers obtained from reputed seed/tuber importer at Lahore, Pakistan.Uniform tubers of same size (35 cm 3 ) were grown in mixture containing silt, clay and farm yard manure at 1:1:1 in the field under shade house conditions.They were kept in 60% shade in a shade house (CONOVER and POOLE, 1973).Randomized Complete Block Design with a split plot arrangement was used in the experiment with three replications having 48 tubers in each replication.Sowing dates (30 th March, 15 th April and 30 th April) were assigned to main plots and sowing depths (2.5 cm, 5 cm, 7.5 cm, and 10 cm) were kept in sub plots.The data were statistically analyzed using analysis of variance.Means were compared using LSD test at 0.05 level of probability, when the F-values were significant (JAN et al., 2009).

Vegetative growth
Sprouting period/time Data regarding days taken to sprouting was significantly affected by planting dates, while the effect of planting depth and the interaction between sowing dates and depths were not significant.Maximum days to sprouting (32 days) was taken by the tubers sown on 30 th March, followed by the tubers planted on 15 th April (25 days), whereas minimum days to sprouting (22 days) were recorded by tubers sown on 30 th April (Table 1).This pattern indicates that tubers sown at the end of April took minimum days to sprouting as temperature remained favorable for sprouting.These findings are in close conformity with the results reported by BROWN (2003), He observed that Caladium respond best to sprouting in warm condition as compared to cold.As planting depths are concerned, more time i.e. 27 days to sprouting were taken by tubers sown at 10 cm depth while fewer days to sprouting i.e. 25 days were taken by tubers sown at a depth of 2.5 cm (Table 1).This shows that with increasing depth sprouting is delayed.Lee et al. (1997) observed that with increase in planting depth, seeds sprouting were delayed.Galavi et al. ( 2008) also reported similar findings that sprouting of tubers is appreciably decreased with increasing planting depth.

Number of sprouts plant -1
Production of sprouts is one of the key objectives of Caladium growers as they are mean of propagation and costly market item.It was seen that maximum number of sprouts plant -1 (2.21) was recorded in tubers sown on 30 th March, followed by tubers sown on 30 th April (1.65) while tubers sown on 15 th April resulted in minimum number of sprouts plant -1 (1.53).In case of planting depth, insignificantly higher number of sprouts plant -1 (2.5) was recorded by tubers sown at a depth of 7.5 cm, while lower number of sprouts plant -1 (1.61) was noted at 5 cm depth (Table 2).The present results are in contrast to those reported by Negb et al. (1989), who observed that number of buds sprouted from shallow planted bulbous plant is significantly higher than from deep planted.Plant height (cm) Table 3 indicates that planting depths has significant effect on plant height while the effect of sowing dates as well as interaction between the two factors found insignificant.Findings revealed that maximum plant height (49.42 cm) was attained by the tuber sown on 30 th March, while minimum plant height (48.83cm) was attained by tubers sown on 15 th and 30 th April respectively.Planting depths significantly affected plant height as maximum plant height (52 cm) was observed in tubers sown at a depth of 7.5 cm, trailed by 5 cm (49.22 cm), while minimum plant height (46.56 cm) was accomplished by the tubers sown at a depth of 2.5 cm.The results of current studies are inline with those reported by Wolf et al. (1990) who observed that high temperatures and long days enhanced plant height and number of leaves.They further reported that tubers planted in the late March produced the tallest plants.The results are also in line with Lee et al. (1997) who observed the best growth in term of plant height and number of leaves obtained from the tubers planted at a depth of 6 cm.

Reproductive growth:
Tuber weight plant -1 Tuber weight plant -1 was significantly affected by sowing dates and planting depths whereas the interaction between the two under test factors was non significant.Table 4 shows that maximum tuber weight plant -1 (48.58 g) was observed in tubers sown on 30 th March, followed by 15 th April (44.62 g), while sowing on 30 th April resulted in minimum tuber weight plant -1 (39.36 g).Maximum tuber weight plant -1 (47.59 g) was recorded in tubers sown at a depth of 7.5 cm, whilst minimum tubers weight plant -1 (40.80 g) was observed at 2.5 cm depth (Table 4).The same pattern was reported by Lorenz ( 2003) who observed that best sowing depth for enhancing tuber production was 4-6 inches.The interaction between sowing dates and planting depths was not significant, however maximum tuber weight plant 1 (58.20 g) was recorded in tubers sown on 30 th March at a depth of 7.5 cm, while minimum tuber weight plant -1 (37.92 g) was observed in tubers sown on 30 th April at a depth of 5.0 cm.Tuber size (cm 3 ) The analysis of (Table 5) indicates that tuber size was significantly affected by planting dates, while the effect of planting depths as will as interaction between the two factors was not significant.Mean value the data showed that higher tuber size (40.88 cm 3 ) was produced in tubers sown on 30 th March, followed by the tubers sown on 15 th April (35.77cm 3 ), whereas minimum tuber size (33.29 cm 3 ) was recorded in tubers sown on 30 th April.In case of planting depths, a non significant response was observed on tuber size, however higher tuber size was recorded in plants sown 7.5 cm deep (41.76 cm 3 ).Current studies further revealed that minimum tuber size (33.70 cm 3 ) was recorded in plants sown at a depth of 10 cm.The same pattern reported by David (1987) who concluded that increasing sowing depth increases tuber size.

Number of tuber plant -1
Planting depth had positive effect on tuber production, while planting date and interaction between the two factors was insignificant.However, higher number of tubers plant -1 (1.85) was observed in tubers sown on 30 th March, whereas sowing on 30 th April resulted in lowest number of tuber plant -1 (1.73).In case of planting depth, higher number of tuber plant -1 (1.92) was recorded in tuber sown at 10 cm depth, followed by 2.5 cm depth (1.89) which were statistically at same level with all the three planting depth except 5 cm (1.53).These results are in line with Barry et al, (2001) who stated that planting depth of 5.0 cm was suitable for enhance tuber production.Table 7 indicates that tubers yield was significantly affected by both the planting depths and planting dates while interaction between the two factors was insignificant.Highest number of tuber yield (5397 kg ha -1 ) was observed in tubers sown on 30 th March, followed by 15 th April (4958 kg ha -1 ), whereas tubers sown on 30 th April resulted in lowest number of tuber yield (4374 kg ha -1 ).These results are in line with those reported by Kaukoranta and Hakala (2008) who stated that earlier sowing of spring tuber crop had positive affect on yield potential of tubers.In case of planting depths, mean value of the data revealed that greatest tuber yield (5288 kg -1 ) was recorded in tubers sown at 7.5 cm depth, followed by planting depth of 5.0 cm (4973 kg ha -1 ), which were statistically at par with both planting depth at 2.5 cm and 10.0 cm.planting depth in 2.5 cm resulted in lowest tuber yield (4532 kg ha -1 ).

CONCLUSIONS
Caladium tubers sown on 30th March resulted in maximum number of tubers, weight plant -1 and tuber yield.On the other hand, tuber sown at a depth of 7.5 cm produced significantly higher tuber number, tuber size and tuber yield.The trend in current study shows that 30 th March is the best sowing time for obtaining maximum yield.Similarly maximum plant height, tuber size, tuber weight plant -1 and tuber yield may be obtained when Caladium tubers sown at a depth of 7.5 cm.The present study recommends that Caladium tuber be sown at the end of March at a depth of 7.5 cm for quality tubers production.It is additionally recommended that further research work on spacing and nitrogen requirements need to be initiated to authenticate current findings which may help in formulating general recommendations for Caladium growers.

Table 1 .
Sprouting period (Days) as affected by sowing dates and planting depths in Caladium.
LSD value at 5% for Planting dates= 4.028 * Do not differ by the LSD test at 5% of error probability

Table 2 .
Number of sprout plant -1 as affected by sowing dates and planting depths in Caladium.

Table 3 .
Plant height (cm) as affected by sowing dates and planting depth in Caladium.

Table 4 .
Tuber weight (g) plant -1 as affected by sowing dates and planting depths in Caladium.

Table 5 .
Tuber size (cm 3 ) as affected by sowing dates and planting depths in Caladium.

Table 6 .
Number of tubers plant -1 as affected by sowing dates and planting depths in Caladium.

Table 7 .
Tuber yield kg ha -1 as affected by sowing dates and planting depth in Caladium.value at 5% for Planting dates=508.4,Planting depths=746.6 * Do not differ by the LSD test at 5% of error probability LSD