Growth and ecophysiology of succulent seedlings under the protection of nurse plants in the Southern Chihuahuan Desert

Abstract

In arid zones, light and water are two important factors that limit seedling development. The shade provided by nurse plants can reduce overheating, excessive transpiration, and photoinhibition in protégé seedlings. The difference that a nurse plant microenvironment may provide on the physiological performance of succulent desert seedlings could be tested by measuring plant growth and photosynthesis. Specifically, in this study we measured the variables related to chlorophyll fluorescence: Quantum yield of photosystem II photochemistry (ΦPSII) and electron transport rate (ETR), as well as relative growth rate (RGR) and its components (net assimilation rate, NAR, and leaf area rate, LAR), root to shoot (R/S) ratio, and relative water content (RWC) for seedlings transplanted under nurse plants and seedlings transplanted under direct sunlight. We tested whether ΦPSII, ETR, LAR, R/S ratio, and RWC, were lower, and RGR and NAR were higher for seedlings of seven succulent species common to the Southern Chihuahuan Desert (Agave lechuguilla, A. salmiana, Echinocactus platyacanthus, Ferocactus histrix, Myrtillocactus geometrizans, Stenocactus coptonogonus and Yucca filifera) grown under direct sunlight than for those grown under nurse Mesquite trees. Although species responded differently to treatments, in general we found that seedlings grown under nurse plants had higher ΦPSII and lower ETR than those grown under direct sunlight. RWC, R/S ratio, and RGR and its components varied in response to microenvironments for some species but not consistently. The ecophysiology variables tested here were more clearly affected by solar radiation than the morphology variables. These results are the first field study including the ecophysiological and morphological mechanisms of seedlings of succulent species under nurse plants.

Seedling survival of three endemic and threatenedMexican cacti under induced climate change

“…; Pérez‐Sánchez et al . ). This study is the first focused on experimentally evaluating the potential impact of climate warming on seedling survival of endangered cacti species.…”

“…After induced warming for the 4 months of the growing season, we found significantly less seedling survival for E. platyacanthus f. visnaga, F. histrix and S. coptonogonus seedlings inside OTCs. Most predictions of global changes have been suggested for adult plants, and there are very few studies taking into account seedlings or young plants (Shryock et al 2014), which are perhaps more susceptible to extreme temperatures (Drennan 2009) and drought (Delgado-Sánchez et al 2013;Pérez-Sánchez et al 2015). This study is the first focused on experimentally evaluating the potential impact of climate warming on seedling survival of endangered cacti species.…”

High tolerance to high-light conditions for the protected species Ariocarpus kotschoubeyanus (Cactaceae)

“…These authors found that the Φ PSII of 1-week old Pachycereus weberi and Escontria chiotilla seedlings was higher in the shade than in high-light. Pérez-Sánchez et al (2015) also found that Φ PSII values of seedlings from seven succulent species, four cacti ( Echinocactus platyacanthus , Ferocactus histrix , Myrtillocactus geometrizans and Stenocactus coptonogonus ) and three Asparagaceae ( Agave lechuguilla , Agave salmiana and Yucca filifera ) were greater under nurse plants than in open spaces.…”

“…Relationships can vary between cactus species and environments and perhaps multiple causes could be involved in facilitation by nurse plants ( Valiente-Banuet et al , 1991 ; Muro-Pérez et al , 2012 ). Thus, shade can be beneficial by reducing overheating, excessive transpiration and photoinhibition that plants growing in open areas may experience ( Flores and Jurado, 2003 ; Pérez-Sánchez et al , 2015 ). However, shade may also represent a cost for the cacti in terms of photosynthetically active radiation because it could induce stress by limiting photosynthesis and arrest plant development ( Kitajima and Fenner, 2000 ).…”

Potential impact of global warming on seed bank, dormancy and germination of three succulent species from the Chihuahuan Desert

“…In the Southern Chihuahuan Desert, soil temperature can, for short periods reach ~45°C at the hottest time of the day (Pérez-Sánchez et al , 2015). During the study period, we found a higher maximum temperature in OTCs in mid-spring of 47°C.…”