MITIGATION OF LATE PLANTING-INDUCED COLD STRESS IN TOMATO WITH GIBBERELLIC ACID AND CALCIUM

Abstract

The experiment was conducted in the farm of Sher-e-l3angla Agricultural University, Dhaka, during the period from 15 November 2013 to 15 April 2014 to find out the role of exogenous application of gibberellic acid (GA3) and calcium (Ca2 ) on the improvement of morpho-physiology and fruit yield of tomato placed to late transplanting-induced cold injury. In this study, variety BAR!Tomato 15 was used as a planting material and the treatments consisted of three different times of transplanting, T, First transplanting time (10 December2013), T, = Second transplanting time (20 December2013), I; = Third transplanting time (30 December2013); and six different combination of gibberellic acid and calcium viz. Mo = 0 ppm (IA; and 0mM Ct, Mi = 20 ppm GA3 and 0 mM Ct. Mi = 0 ppm GA3 and 5 mM Ca2 , M;= 20 ppm GA3 and 5mM Ca2', M4= 0 ppm GA3 and 10mM Ca2? and Mc = 20 ppm GA; and 10mM Ca2'. The experiment was laid out in two factors Randomized Complete Block Design (RCBD) with three replications. The total treatment combinations were 18 (3x6). Most of the results of this experiment showed differences to the treatments. The first transplanting time significantly influenced to increased morpho-physiological characters: plant height, number of leaves plant", number of branches plant' and SPAD value of leaf; yield contributing characters: number of flowers plant', number of fruits plant', fruit length, fruit diameter and yield plot4 and ha` compared to late or third transplanting time-induced cold stress. The maximum yield (80.46 t ha") was obtained from Ii whereas the lowest yield was found (58.53 t ha") from T3 transplanting and suggesting that early transplanting time improves fruit yield through promoting the morpho-physiological features of tomato. In this study it was found that different combination of GM and Ca2 mitigated the adverse effects of late transplanting-induced cold stress in tomato. Exogenous foliar application of 20 ppm gibberellic acid (GA3) along with 5 mM calcium (Ca2') improved the morphological characters of tomato except number of branch plant". The yield contributing characters and fruit yield showed statistically significant increased with 20 ppm gibberellic acid (GM) along with 5 mM calcium (Ca2 ). The highest yield 83.99 t ha" yield were found with the 20 ppm gibberellic acid (GA;) along with 5 mM calcium (Ca2D but the lowest 59.92 t ha" yield were recorded from control. These results indicated that combined application of GA; along with Ca2' has positive impact on fruit yield. The interaction between date of transplanting and sole or combined application of GA3 and Ca2 influenced all the morpho-physiological and yield contributing characters and yield of tomato. The highest yield (93.54 t ha") of tomato was obtained with the first transplanting time along with 20 ppm GA3 with 5 mM Ca2 (TiM3) treatment combination, whereas the lowest yield (49.79 t ha") was recorded from LM0, third transplanting date and 0 ppm GA3 and 0 mM Ca2 treatment combination. In addition the treatments combination T3M3 influenced to produce the highest yield 69.09 t ha" out of all the treatment under late transplanting and suggested that 20 ppm GA3 along with 5 mM Ca' successfully mitigate the detrimental effect of cold stress in variety BAR!tomato IS.