Growth and Anatomical Adaptations in Response to Salinity Stress in Cucurbita moschata Duchesne ‘Butternut’ (Cucurbitaceae)

Sains Malaysiana 51(5)(2022): 1317-1324 http://doi.org/10.17576/jsm-2022-5105-04

ABSTRACT Pumpkin or squash is an economically important crop that is moderately sensitive to salinity but how its growth is affected by soil salinity is poorly understood. Salinity stress on physiological and anatomical traits of Cucurbita moschata ‘Butternut’ was investigated under hydroponic culture using Hoagland’s solution with various NaCl concentrations (0, 25, 50, 75, 100, and 150 mM) for four weeks. The results showed that pumpkin growth characters decreased after cultured in various NaCl concentrations. Leaf number, leaf width, leaf length, root number, stem height, stem diameter, green intensity in terms of SPAD units, chlorophyll fluorescence (Fv’/Fm’, Fv/Fm), total chlorophyll, chlorophyll a and chlorophyll b contents significantly (p < 0.05) decreased after culture in various NaCl concentrations. Salinity stress impacted fiber layer thickness, vascular bundle size and vessel diameter of treated plants but did not affect cuticle thickness. Physiological and anatomical traits significantly correlated with salinity gradients, except for chlorophyll b and chlorophyll fluorescence, in both light and dark condition. Results provide significant data to improve the understanding of adaptation mechanisms of tolerant pumpkin cultivars under salinity stress condition.

INTRODUCTION Soil salinity is one of the most severe global stressors, affecting approximately 20% of irrigated land anddrastically reducing crop yields (Okon 2019). Plants are extremely susceptible to salinity during both the vegetative and reproductive stages (Hussain et al.2017). Salinity weakens plant growth by decreasing soil osmotic potential, leading to loss of water in plant cells, while sodium and chloride ions are toxic toward plant nutrients (Kurum et al. 2013; Martins et al. 2013). Plants that are unable to adapt to salinity wither and eventually die. However, numerous plants species can adapt under salinity stress by utilizing biochemical pathways that promote growth and development through water management as a response to environmental situations (Albuquerque et al. 2016; Brito et al. 2014; Kurum et al. 2013; Oliveira et al. 2015). Many studies have reported plant adaptation under salinity conditions including lettuce (Lactuca sativa) (Oliveira 2013), watermelon (Citrullus lanatus) (Martins et al. 2013), Sporobolus arabicus (Hameed et al. 2013), squash (Cucurbita maxima) (Oliveira et al. 2014), beet (Beta vulgaris) (Oliveira et al. 2015), cucumber (Cucumis sativus) (Albuquerque et al. 2016), Salvadora persica (Parida et al. 2016), and pumpkin (Cucurbita moschata or Cucurbita pepo) (Bischoff 1999).

Pumpkin or squash is an important crop belonging to the family Cucurbitaceae. Numerous well-known cultivars include C. moschata, C. pepo, and the squash C. maxima. Cucurbitaceae species comprise the second highest global crop value (FAO 2014; Resende et al. 2013). Winter squash and pumpkin have been used to graft many cultivars of watermelon, melon and cucumber (Salehi et al. 2008). Winter squash and pumpkin varieties can reduce sodium ion poisoning (Balkaya et al. 2016). Pumpkins are moderately sensitive to salinity because the fairly deep root system increases the absorption of groundwater (Bischoff 1999). There are many varieties of pumpkin and squash but how their growth is affected by soil salinity is poorly perceived and understood. No previous reports have considered the physiology and anatomy of pumpkin C. moschata ‘Butternut’ under salinity cultivation. Here, the growth and stem anatomy of pumpkin ‘Butternut’ were investigated under salinity stress. Results can be applied to adapt other plant species or pumpkin cultivars in soil salinity situations. 

Sains Malaysiana 51(5)(2022): 1317-1324 http://doi.org/10.17576/jsm-2022-5105-04