Simulated rainfall sequences affect germination and biomass allocation of Chihuahuan desert native plants

Ecological restoration of many arid zones is a pressing issue because of recurrent loss of plant cover. Here, we conducted a germination and growth study of three framework plant species, native to the Chihuahuan Desert in Northern Mexico, to optimize the establishment for arid zone restoration. The plant species were Zinnia grandiflora Nutt., Menodora scabra A. Gray, and Yucca elata (Engelm.) Engelm, which were selected for their potential for restoration as drought tolerant species. We evaluated seed germination, survival, and biomass allocation of seedlings under four (high, medium, low, and very low) simulated rainfall sequences as irrigation treatments. Rainfall sequences were obtained from a previous study that considered 35?years of precipitation records. Each sequence is accounted for 20% of probability of a wet, normal, low, or very low year in terms of precipitation occurring in the study area. Germination was conducted in controlled greenhouse conditions and seeding was done in pots containing soil mix. Sequences produced soil moisture fluctuations in which germination percent was higher for M. scabra (88%) and Z. grandiflora (31%) on the high sequence compared to the other sequences. Survival at the end of the treatments was above 80% of all the three species, and seedlings allocated more aboveground biomass as the moisture increased and more belowground biomass as moisture decreased. Implications under our study conditions include that germination of Y. elata would not be negatively affected by low soil moisture, and the best germinative results for Z. grandiflora and M. scabra would be achieved under higher soil moisture.