Role of Salicylic Acid on Growth, Yield, Qualityand Disease Pest Reaction of Onion (Allium Cepal.) CV. Agrifound Light Red

SAARC J. Agric., 18(1): 39-49 (2020) DOI: https://doi.org/10.3329/sja.v18i1.48380 Research Article ROLE OF SALICYLIC ACID ON GROWTH, YIELD, QUALITYAND DISEASE PEST REACTION OF ONION (ALLIUM CEPAL.) CV. AGRIFOUND LIGHT RED P. Bhasker*, P.K. Gupta and H.P. Sharma Department of Plant Physiology, National Horticultural Research and Development Foundation, Chitegaon Phata, Nashik, Maharashtra, India ABSTRACT Salicylic acid (SA) is endogenous naturally occurring plant growth hormone acting as an important signaling molecule adds tolerance against abiotic stress. A field experiment was conducted to assess the efficacy of exogenous application of SA on growth, yield and storage performances of onion during Rabi 2012-13, 2013-14 and 2014-15. The experiment was comprised of 6 different treatments of SA including control. Exogenous applications of all SA treatments significantly influenced plant growth and development. The treatment application of SA at 30 days after seed sowing and second spray at 30 days after transplanting and third spray at 60 days after transplanting performed superior in terms of growth, development and yield. Exogenous application of SA significantly influenced on thrips population and stemphylium blight disease incidence and intensity. The results also revealed that SA partially involved in post-harvest management of onion. Keywords: Foliar application, Insect, Onion, Post-harvest storage, Salicylic acid INTRODUCTION Onion (Allium cepa L.) is one of the most important commercial vegetable crops grown in India. The highest foreign exchange earner with higher medicinal as well as consumption values (Bhasker et al., 2018) among all the vegetable crops. India ranks second in area as well as in production in the world after China. Thearea and production of onion in India is 11,81,000 hectares and 18,9,24,000 tons, respectively, with an average yield of 16 t ha-1 (National Horticultural Board, 2017). The lower productivity is due to cultivation of low yielding potential of open pollinated conventional varieties which are susceptible to biotic factors and includes bacteria, * Corresponding author: Received: 13.02.2019 Accepted: 26.04.2019 40 Bhasker et al. fungi, viruses, insects, and abiotic factors i.e. drought, salinity, heat, cold and heavy metal stress. Plants have evolved broad and efficient self-mechanisms to cope with these continuous adverse challenges and to obtain an adequate defense mechanism against biotic and abiotic constrains (Nazar et al., 2011). Plants have a prominent defensive response against biotic (pathogen) attack by the synthesis of low molecular compounds with disparate functions in pathogen interactions of plant (Dixon, 2001). Salicylic Acid (SA) (2-hydroxybenzoic acid), is recently included in the category of plant growth hormones. It is an important signal molecule belonging to an extra ordinary diverse group of plant phenolic compound synthesized under different biotic and abiotic stresses (Vlot et al., 2009; Bideshki and Arvin, 2010; Miura and Tada, 2014; Shama et al., 2016). SA is distributed in wide range of plant species and act as a defensive signal that is essential for elicitor triggered immunity and the establishment of Systematic Acquired Resistance (SAR) by inducing particular enzymes involved in biosynthetic reactions (Carr et al., 2010). Thus, SA is an endogenous growth regulator, which participates in regulation of several physiological processes in crop plants viz., closing of stomata, induction of flower, ion uptake, inhibition of ethylene biosynthesis and transpiration (Khan et al., 2003; Hayat et al., 2009) and it also involved in reverses the effects of ABA on leaf abscission by this ameliorates the growth of crop.SA promotes resistance against several viral, fungal and bacterial pathogens in various crops viz. tomato (He and Zhu, 2008; Pandey and Gupta, 2012) and carrot (Hayat et al., 2009) with a diverse way of defense strategies in which SA play a core role and is the key element in both local and systemic defense, but limited information is available about SA effects on purple blotch (Alternaria porii) and stemphylium blight (Stemphylium vesicarium) in onion. In addition to its role towards biotic stresses, SA is also proved believed to play a key role in plant responses to many abiotic stresses such as heat stress in mustard (Dat et al., 1998), ozone in turnip (Kachroo et al., 2000), drought stress in wheat (Singh and Usha, 2003), mustard (Nazara et al., 2015), soybean (Nasrin et al., 2017) and chilling stress in peach (Zhang et al., 2017). The earlier studies have reported that foliar application of SA play a significant role in plant water relations, photosynthesis (Habibi, 2012; Nazara et al., 2015) including increases in yield in several crops like garlic (Bideshki and Arvin, 2010), brinjal (Gawade and Sirohi, 2011) and tomato (Nigar et al., 2017). There is a limited literature is available of SA role on one of the most important export oriented onion crop. The pre harvest sprays of chemicals such as maleic hydrazide, ethrel, cycocel, carbendazim, benomyl, streptocycline treatments widely applied without impairing the keeping quality of onion. Pre harvest foliar application of these chemicals has gained prominence and facilitates the maintenance of quality of onion bulbs on storage with respect to inhibition of sprouting, rotting and reduction in the physiological loss in weight. Therefore, the present experiment focused on the effect of foliar application of SA on plant growth, yield, disease and insect resistance and also an attempt was made to study the role of SA in post-harvest storage of onion. 41 ROLE OF SALICYLIC ACID ON ONION YIELD MATERIALS AND METHODS A field trial was conducted to assess the influence of salicylic acid (SA) on the production of onion at the research farm of National Horticultural Research and Development Foundation (NHRDF), Nashik, Maharashtra, India during Rabi, 201213, 2013-14 and 2014-15 under “All India Network Research Project on Onion and Garlic”. The field is situated at 20’. N latitude and 78.73º 57’ E longitude and 492 meter above mean sea level. The fertility status of experimental plot soil belongs to deep heavy clay with pH (7.60), electrical conductivity (0.133 ds m-1), organic carbon (0.75 mg g-1), available nitrogen (374.0 kg ha-1), available phosphorus (49.05 kg ha1 ), available potassium (414.4 kg ha-1), available sulphur (19.77 kg ha-1), available Fe (14.12 kg ha-1), available Mn (10.83 mg kg-1), available Zn (0.911 mg kg-1), available Cu (1.361 mg kg-1) and available B (0.63 mg kg-1). The water holding capacity at saturation was 62.8%, field capacity 38.9% and permanent wilting point was 24.6% on volume basis. During experimental period of three consecutive years meteorological data are listed in Fig. 1. Temp. Max.(°C) Temp. Min.(°C) RH Max. (%) 30 160 140 25 RH (%) & Rainfall (mm) Temperatute °C 120 20 100 15 80 60 10 40 5 20 (...truncated)