Comparative Water Relations of Two Contrasting Date Palm Genotypes under Salinity

Abstract

Salinity is a global agricultural problem, resulting in a significant reduction in the plantation areas and the crop yields, especially in arid and semiarid regions. The date palm is relatively salt-tolerant plant species, although the nature of salt tolerance is poorly understood. In this study, the salt stress responses of a salt-tolerant “Umsila” was compared with salt-susceptible “Zabad” date palm cultivars. Various physiological parameters, plant-water relations, and anatomical characteristics were analyzed. The results revealed that although salinity has negatively affected both cultivars, Umsila exhibited more stable photosynthesis than Zabad as reflected by the quantum yield (Qy) and the stomatal conductance (GS). Similarly, Umsila showed a more dynamic root system and efficient water relations than Zabad as demonstrated by the leaf water potential (LWP) and relative water content (RWC) during salinity. Umsila also accumulated greater abundances of soluble sugars, potassium (K+), calcium (Ca+2), proline, glycine betaine, and lignin and formed extra layers of Casparian strips in the root tissues when the seedlings were grown under saline conditions. Together, the results obtained from this study have offered some insights into the salt tolerance mechanisms in the date palm.

Physiological responses of date palm (Phoenix dactylifera) seedlings to seawater and flooding

“…5), suggesting that free amino acids were more important as osmolytes than sugars (Hartzendorf & Rolletschek, 2001). However, salt induced accumulations of proline (Djibril et al, 2005;Yaish, 2015;Al Kharusi et al, 2019a) were not observed in the current study, probably due to the intraspecific variations of date palm (Al Kharusi et al, 2019a,b), as well as a counteraction of flooding as reported in several other species, for example cabbage palm (Williams, 1996), Juncus kraussii (Naidoo & Kift, 2006). Much stronger accumulation of amino acids were Asterisks indicate significant differences at: *, P < 0.05; **, P < 0.01; ***, P < 0.001; respectively, between the seawater flooding and control treatments examined using Student's t-test (n = 5-6).…”

“…Although date palms are thought to be a salt‐tolerant crop able to grow in soils up to 12 dS m –1 without showing symptoms of salt stress (Ramoliya & Pandey, 2003; Yaish & Kumar, 2015; Patankar et al ., 2019; Al‐Harrasi et al ., 2020), salinity can lead to significant economic losses in date palms (Tripler et al ., 2011; Yaish & Kumar, 2015; Al‐Muaini et al ., 2019). This is particularly observed in salt susceptible cultivars (Al Kharusi et al ., 2017, 2019a; Hazzouri et al ., 2020), which showed significantly declined photosynthesis, shoot and root growth and foliar water content under salt stress (Alhammadi & Edward, 2009; Al Kharusi et al ., 2017). Salt stress affects their growth and productivity independently of drought and heat (Alhammadi & Kurup, 2012), and constitutes an increasing problem in date palm plantations due to irrigation and fertilisation.…”

Prospects for the Study and Improvement of Abiotic Stress Tolerance in Date Palms in the Post-genomics Era

“…Al Kharusi et al (2019b) studied the seedling offspring of a salt tolerant variety, 'Umsila, ' and salt sensitive variety, 'Zabad.' They reported that salt tolerant seedlings responded to salinity by developing a thicker protective Casparian strip in roots, increasing osmolyte and compatible solute concentrations including proline, glycine betaine, and total sugar.…”

Review: Challenges and opportunities of implementing mass productivity scale (MPS) at date farms in Malaysia

“…Until present time, exceptionally powerful control measures have yet to be found. Sadly, that creepy crawly bug type, the red palm weevil, is the starting point from tropical South Asian (Al- Kharusi et al, 2019). Moreover, the illnesses are also caused essentially by parasites and phytoplasma, for example, deadly yellowing and Bayoud Fusarium shrink, which are the danger to the date palm in Malaysia.…”

“…Despite large volume of date import every year, Malaysia also produces local dates in small scale farm concept. Unfortunately, these smallholder farmers lack of knowledge and information about standard farm management of dates, resulting in poor farm production practice and methods (Young, 2010, Al-Kharusi et al, 2019. Hence, the presence of small scale farming with low production of dates can be seen as such a potential matter to improve this sector.…”