Abstract: Both time and concentrations had affected significantly the growth parameters of plants. Maximum days to flowering (42.67), fruit per plant (77.69), plant height (77.78 cm), fruit weight (71.15 gm), number of branches (12.33) per plant and total yield (26840 kg ha -1) were recorded in the plants sprayed with 60 mg/lit of gibberellic acid 10 days before transplantation, while minimum values were noted in controlled treatment. Maximum fruit drop per plant was found for control treatment and minimum for the plants treated with gibberellic acid at 60 mg/lit. It is suggested that tomato should be supplied with gibberellic acid at 60 mg/lit. 10 days before transplantation under the agroclimatic conditions of Peshawar.
Introduction
Gibberellic acid is one of the most important growth stimulating substances used in agriculture since long ago. It may promote cell elongation, cell division and thus helps in the growth and development of many plant species. Like other developing countries, the population of Pakistan has been increasing day by day and there is a threat of food shortage in near future. Authorities are of the view yield was tomato spring crop can be increased by giving due consideration of different times and concentrations of gibberllic acid. ln NWFP area under tomato cultivation was 12200 hectares with a production of 123100 tones in year 1997-98.
The research project was initiated to find out the best level of gibberellic acid and its time of application for the maximum yield of tomato crop. Plummer and Tomoes (1953) worked on the effect of indole acetic acid and gibberellic acid on normal and dwarf tomatoes. They observed that both varieties did not show significant indole acetic acid while the dwarf plants treated with gibberellic acid exceeded in height than untreated normal plants. Gibberellic acid at the rates of 100-200 mg/plant caused total stem elongation, but the lower rates had no effect. In case of young plants however, stem elongation was increased by all concentration between 2 to 450 mg/plants. He has found that the leaves were enlarged and had entire margins (Rappaport, 1957). Gibberellic acid when applied to flowers controlled fruit drop in tomato (Foefanova, 1962).
Materials and Methods
The seeds were sown on November 15, 1995. Irrigation and weeding were done whenever necessary. The experimental plot was ploughed, well prepared and a uniform dose of 100 kg P2O5 in the form of super phosphate and 50 kg N in the form of ammonium nitrate per hectare was applied before transplanting the seedlings. The beds were raised 12 cm from the soil surface to provide good drainage.
Seedlings of uniform size were transplanted in the 2nd week of February, 1996 and were irrigated. Second irrigation was done after three days of first irrigation. 50 kg/hectare of fertilizers was applied after two weeks of transplantation.
The experiment was laid out in split plot design with three rep lications. Three different concentrations of gibberellic acid along with control were used. Each subplot was 5×1×2 m3 with 5 m length, 1 m width and 2 number of rows. The seedlings were planted with 45 cm distance in between and row to row distance was 90 cm.
Data were recorded on number of days to flowering, number of fruit per plant, fruit drop per plant, plant height (cm), fruit weight (g) and yield (kg ha–1). Least significant difference test (LSD) was used for data analysis and mean separation (2 factorial RCBD).
Results and Discussion
The data showed that various parameters were highly influenced by application of gibberellic acid. Both concentration and time have significant effect on all growth parameters while the interaction effects were non-significant except in total yield.
Days to flowering: Comparing the means of concentrations. It clear from the Table 1 that maximum number of days to flowering (41.17 days) was recorded at a concentration of 60 mg/lit while, followed by 39.50 days using a concentration of 90 mg/lit while minimum number of days to flowering (37.75) was noticed in control treatment. The means of different time of GA3 application (Table 1), revealed that maximum number of days to flowering 40.92 was observed in plants which were sprayed 10 days after transplantation, while minimum number of days at the time of fruit setting. Though interaction effects were non significant however, maximum and minimum number of days to flowering (42.67) and (36.00) were for concentration of 60 mg/lit sprayed 10 days before transplantation and in control treatment sprayed at the time of fruit set, respectively. The reason is that gibberellic acid before trans plantation to the field delays the emergence of flowers in tomato (Courter and Water, 1962).
Number of fruit per plant: Comparing the means of concentration, it is cleared from the Table 2 that maximum number of fruit/plant (69.08) was recorded for tomato at the concentration of 60 mg/lit. Average number of fruit/plant (59.98) with a concentration of 90 mg/lit while minimum average number of fruit/plant (36.75) was noted in controlled in comparison of different times, highest number of fruit/plant (60.9 8) was observed in plants which were sprayed 10 days before transplantation followed by (56.67) which were sprayed after 20 days of transplantation while minimum number of fruit/plant (50.67) was recorded for the plants sprayed at the time of fruit set. Though interaction effects were non significant, however, maximum number of fruit/plant (77.67) and minimum number of fruit/plant (34.33) were recorded for concentration of 60 mg/lit sprayed 10 days before transplantation and in control plot sprayed at the time of fruit set, respectively (Table 1).
| Table 1: | Effect of different time and concentrations of qibberellic acid on number of days to flowering of tomato CV. Roma. |
| LSD value for time at 5% level of probability= 0.4331, LSD Value for conentraions at 5% level of probability =0.9341 | |
| Table 2: | Effect of different time and concentrations of gibberellic acid on the average number of fruit per plant of tomato CV. Roma. |
| LSD value for time at 5% level of probability =3.768, LSD Value for conentraions at 5% level of probability = 4.032 | |
| Table 3: | Effect of different time and concentrations of gibberellic acid on the fruit drop/plant of tomato CV. Roma. |
| LSD value for time at 5% level of probability =0.5064, LSD Value for conentraions at 5% level of probability= 0.6881 | |
| Table 4: | Effect of different time and concentrations of gibberellic acid on plant height (cm) of tomato CV. Roma. |
| LSD value for time at 5% level of probability= 2.352, LSD Value for conentraions at 5% level of probability =3.358 | |
| Table 5: | Effect of different time and concentrations of gibberellic acid on fruit weight (gm) of tomato CV. Roma. |
| LSD value for time at 5% level of probability =1.210 LSD, Value for conentraions at 5% level of probability = 1.823 | |
| Table 6: | Effect of different time and concentrations of qibberellic acid on the total yield (kg ha–1) of tomato CV. Roma |
| LSD value for time at 5% level of probability=862.1, LSD Value for conentraions at 5% level of probability=464.7, LSD Value for interaction at 5% level of probability=929.4 | |
The reason is that gibberellic acid increased the clusters of flower and number of fruit set per plant.
Fruit drop per plant: Comparing the means of concentrations maximum tomato fruit drop per plant (13.67) was recorded h control treatment followed by (11.25) with the concentration o f 90 mg/lit of GA3 while minimum tomato fruit drop (8.00) was noted for plants at a concentration of 60 mg/lit of. The means of different times revealed that GA3 maximum tomato fruit drop per plant (12.50) was observed in plants which were sprayed 20 days after transplantation followed by plants (11.67) which were sprayed at fruit set, while minimum tomato fruit drop per plant (8.50) was recorded for the plants prayed 10 days before transplantation (Table 3). Though interaction effects were non significant however, maximum tomato fruit drop per plant (15.33) and minimum (5.33) were recorded for control plot sprayed after 20 days of transplantation and concentration of 60 mg/lit sprayed 10 days before trans plantation respectively. As the gibberellic acid enhance fruit setting and control the fruit drop in tomato (Foefanova, 1962).
Height of plant: Maximum height of tomato per plant 70.58 cm (Table 4) was recorded for tomato at a concentration d 60 mg/lit followed by (59.96 cm) with a concentration of 90 mg/lit, while minimum tomato height per plant (44.06 cm) was noted in control treatment. The means of different time revealed that maximum tomato height per plant (62.44 cm) was observed in plants which were sprayed 10 days before transplantation followed by (58.38 cm) which were sprayed after 20 days of transplantation while minimum height per pIant (52.17 cm) was recorded for the plants sprayed at the time of fruit set. Though interaction effects were nonsignificant, however, maximum height per plant (77.78 cm) and mini mum height per plant (40.75 cm) were recorded for concentration of 60 mg/lit sprayed 10 days before transplantation and in control plot sprayed at the fruit set time respectively. The reason is that gibberellic acid increased cell division, cell elongation & stem elongation that result in an increased plant height.
Weight of fruit: Maximum weight of tomato fruit 68.81 gm (Table 5) was recorded at a concentration of 60 mg/lit followed by (65.71 gm) with a concentration of 90 mg/lit, while minimum weight of tomato fruit (29.13 gm) was noted in control treatment. The means of different time revealed that maximum weight of tomato fruit (59.78 gm) was observed h plants which were sprayed 10 days before transplantation followed by 57.66 gm in plants which were sprayed after 20 days of transplantation while minimum weight of tomato fruit (53.78 gm) was recorded for the plants sprayed at the timed fruit set. Though interaction effects were non significant, however, maximum weight of tomato fruit (71.15 gm) and minimum (26.71 gm) were recorded for concentration of 6O mg/lit sprayed 10 days before transplantation and in control plot sprayed at the time of fruit set, respectively.
Total yield: Maximum yield 24551 kg ha–1 (Table 6) was recorded for tomato at a concentration of 60 mg/lit followed by (23505 kg ha–1) with a concentration of 90 mg/lit, while mini mum yield (14800 kg ha–1) was observed in control. The means of different time revealed that maximum yield (22520 kg ha–1)) was observed in plants which were sprayed 10 days before transplantation followed by (21420 kg ha–1) which we re sprayed after 20 days of transplantation, while minimum yield (13910 kg ha–1) was recorded for the plants sprayed a the time of fruit set. The interaction effects were also significant, however maximum tomato yield (26840 kg ha–1) and minimum yield (13910 kg ha–1) were recorded for concentration of 60 mg/lit sprayed at the time of fruit set, respectively, these results are in agreement with Mozrkar et al. (1991) who also found that application of gibberellic acid increased the total yield of tomato. As all the morphological characteristics i.e, cell division, stem elongation, fruit setting and plant height was increased by application of gibberellic acid so it also result in more yield.
It is concluded that when GA3 was used at a concentration d 60 mg/lit 10 days before transplantation, fruit drop/plant were reduced . However, number of days to flowering, number of ruit per plant, plant height (cm), fruit weight (gm)), number of branches per plant and total yield was maximally increased, while the values of the above mentioned parameters were recorded minimum in control treatment at fruit set. Maximum fruit drop/plant was recorded in control treatment and minimum at 60 mg/lit of gibberellic acid sprayed 10 days before transplantation.