Morphological Performance of Onion under Exogenous Treatments of GA3

Available online: www.notulaebiologicae.ro Print ISSN 2067-3205; Electronic 2067-3264 Not Sci Biol, 2018, 10(1):33-37. DOI: 10.15835/nsb10110087 Original Article Morphological Performance of Onion under Exogenous Treatments of GA3 Md. Dulal SARKAR*, Mohammad SHAHJAHAN, Khairul KABIR, Abu Yousuf SHIHAB, A.N.M. SAYEM Sher-e-Bangla Agricultural University, Faculty of Agriculture, Department of Horticulture, Dhaka-1207, Bangladesh; (*corresponding author); ; ; ; Abstract The present study was conducted to assess the morphological response of onion plants to different GA3 levels (0, 20, 40 and 60 ppm). The factor levels of GA3 were applied during transplanting by root soaking and foliar spray at 30 and 60 days after transplanting. The gibberellic acid had a great effect on increasing plant height (46.50 cm), shoot biomass (641.67 g m-2), bulb biomass (1125.00 g m-2) and also dry matter accumulation in onion plants under the effect of 60 ppm compared to control. Plants grown up without GA3 application were shorter than those grown with GA3 spray where the lowest plant height (34.67 cm) was remarked. The leaf number (11.43) was considerably increased when 60 ppm GA3 was used as the growth promoter factor in comparison to control. The plants attain minimum fresh biomass at harvesting time in the shoot (441.67 g m-2) and bulb (641.67 g m-2) grown in control plot. Considerably (41.63%) more dry shoot biomass accumulation was recorded in 60 ppm GA3 treated plants in comparison with the control at harvesting stages. Insignificant effect by all concentration of GA3 was found in bulb length, fresh root biomass and dry root biomass. Thus, the use of 60 ppm GA3 can be recommend for onion production due to the significantly increased of the fresh bulb biomass with about 42.96% over control. Keywords: Allium cepa; bulb crop; growth regulators; morpho-physiology Introduction Globally, onion (Allium cepa L.) is an important crop that needs proper agricultural management in order to achieve a great flavour and to increase the production in regard with the consumer’s demand (Sharma et al., 2015). It is the main spice crop rather than vegetable and therapeutic in Bangladesh (BBS, 2015). This bulbous crop sparingly holds the first position in terms of production among the spice crops (BBS, 2015). Bangladesh is producing about 1,052 metric tons of onion, over 300 thousand acres of land, with the average yield about 3.33 metric tons per acre (BBS, 2015). Bangladeshi farmers grow onion during both winter and summer seasons, following traditional methods. Although the area and production of onion have been increased compared to an earlier period, still the average yield is lower as compared to much other onion producing neighbouring countries and it may be impossible to accomplish the domestic demand, due to growing population (BBS, 2015). Plant growth regulators have a potential role in modern agriculture (Ashraf et al., 2010) and have been known as key element for vegetative growth and bulbing (Rahman et al., 2004; Ouzounidou et al., 2011). Besides stimulating the growth processes, they also affect seed development, organ elongation, senescence and control of flowering time (Yamaguchi, 2008; Yu et al., 2009; Ghoname et al., 2011). GA3 play a vital role to vigorous growth, that promoted the total plant length of onion by 35% of the control and also increased the number of leaves, fresh and dry weight significantly (Ouzounidou et al., 2011). Thus GA3 have the promoter effect on the growth and development of bulb crops, as well as the total yield (Hye et al., 2002; Islam et al., 2007; Amal and Hegazi, 2009). The option of more expansion of the area under onion cultivation seems unlikely because of intense crop competition. Improving the production of onion using some modern agricultural practices need to be considered. Regarding this, the yield of onion can be increased by using plant growth regulators. Moreover, analysis of morphological features of a plant would be a feasible Received: 05 Nov 2017. Received in revised form: 03 Mar 2018. Accepted: 08 Mar 2018. Published online: 27 Mar 2018. Sarkar MD et al / Not Sci Biol, 2018, 10(1):33-37 34 technique for modelling growth and development of onion plants that is an obligate prerequisite to understanding the behavioural response. The present study aimed to improve the onion production from the scientific and economic point of view. Therefore, an attempt was taken in the present study to evaluate the effect of GA3 on morphological characters of onion and also to test standardized concentrations of GA3. Materials and Methods Plant material and site description The variety ‘BARI Onion-1’ was tested at the horticulture farm of Sher-e-Bangla Agricultural University, Bangladesh in 24.09° N latitude and 90.26°E longitude with an elevation of 8.20 m from sea level. The experimental field is under the subtropical climate characterized by scanty precipitation during the interval from October to March. ‘BARI Onion-1’ is a winter variety and comparatively less susceptible to pest and diseases. Plants were maintained in the open environment under natural sunlight. The soil of the experimental site is in loam textural class (Table 1). Plant growth characters Data was collected on plant growth features (e.g. plant height, leaf number, root length, bulb length and bulb diameter), fresh biomass assimilation (e.g. fresh root biomass, fresh shoot biomass and fresh bulb biomass) and dry biomass accumulation (e.g. dry root biomass, dry shoot biomass and dry bulb biomass). The experimental design The experiment was conducted by Randomized Complete Block Design with three replications. The factor levels of GA3 studied were as follows: (i) Control: 0 ppm (G0), (ii) 20 ppm (G20), (iii) 40 ppm (G40) and (vi) 60 ppm (G60). These three levels of GA3 along with control were applied three times: first one during transplanting by root soaking, while the second and third phase applications were done at 30 and 60 days after transplanting. Growing conditions Required seeds were sown in the seedbed on 15 October 2014 and transplanted into the experimental field on 30 November 2014 at a spacing of 15 cm × 10 cm. After transplanting, the plants were irrigated by watering cane to saturation. Fertilizers were used at the rate of usual range for commercial production at 60, 30, 80, 20, 1.5, 0.7 kg ha-1 for N, P, K, S, Zn, B, and cowdung respectively (FRG, 2012). Intercultural operations were furnished for proper growth and development of the crop. Bulbs were harvested after 90 days after transplanting. Statistical analysis Analysis of variance was performed in order to assess the significance of the effect of GA3 in onion. Tukey’s HSD tests were used to determine variances between each treatment where P<0.05 was considered as significant. Statistical analyses were carried out using IBM SPSS Statistics version 20. Results and Discussion Plant growth characters A significan (...truncated)