Intercropping Halophytes to Mitigate Salinity Stress in Watermelon

Catherine Simpson,Stephen King,Jose Franco,Astrid Volder

doi:10.3390/su10030681

Abstract

Saline irrigation water can lead to salt buildup and reduced crop yields. Halophytic plants are known to accumulate excess salts in tissues, removing them from the immediate environment. This two-phase experiment explored the feasibility of intercropping watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai var. lanatus) with halophytic species to mitigate the negative effects of saline irrigation water while providing a value-added crop. In the first experiment, six greenhouse-grown species were irrigated with water that was either deionized (0 dS m−1) or contained 3 or 6 dS m−1 of salts for 41 days and screened for growth and salt removal. Two halophytes were selected to be additively intercropped with watermelon under field conditions and irrigated with the same saline irrigation levels as the first experiment. Results indicated that garden orache (Atriplex hortensis L.) exhibited the highest growth rates and purslane (Portulaca oleracea L.) accumulated high amounts of sodium in plant tissues under saline irrigation. The field experiment showed that watermelon yields, stem water potential, and fruit quality were not affected by saline irrigation; however, the watermelon/orache intercropping treatment had significantly higher yields. These results suggest intercropping with halophytes has the potential to contribute a value-added crop without reducing watermelon yields.

Highlights

Salinization concerns are escalating as water resources and arable land are decreasing
While little research has been conducted on intercropping with halophytes to remove salts, we found that these six species (Table 1) had varying degrees of salt removing capacity as well as having other potentially marketable qualities by which they were selected
Contrary to what was observed by Zuccarini [26], who found that purslane performed better than orache, we found that orache was a more effective accumulator of Na

Summary

Introduction

Salinization concerns are escalating as water resources and arable land are decreasing. It is estimated that 80 million ha of land are salt affected, with much of this attributed to agricultural inputs [1]. Climate change has resulted in more severe and longer lasting drought in semi-arid and arid climates worldwide, which has resulted in an increase in irrigation use to supplement crop water requirements [3]. In the U.S alone, approximately 55 million acres of land were irrigated in 2012 [4]. It is estimated that between 20% and 50% of irrigated land is salt affected, many of these lands in arid and semi-arid regions that are considered to be more vulnerable [5,6,7]. Relying on low quality water to irrigate crops can cause soil salinization and result in future reduced plant growth and yield. The primary elements associated with toxicity are sodium (Na) and chloride (Cl), which affect plant tissues, osmotic potential, and cell membranes as well as soil properties [10,11,12]

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