Ecology of Sahara Mustard, Brassica tournefortii Jodie S. Holt and Robin G. Marushia University of California, Riverside Cooperators: Matt Brooks and Melissa Trader U.S. Geological Survey Origin and Habitat of B. tournefortii •Mediterranean region •Grows on sand dunes and alluvial sand •Adapted to drier habitats of Middle East, central and western Asia •Grown as oilseed crop in marginal dry lands in India •Considered for breeding for drought and aphid resistance •No hybridization with other Brassica species Brassica tournefortii in the U.S. Brassicas in California •5 related species in California— – Brassica juncea, napus, nigra, rapa (=campestris), geniculata (=Hirschfeldia incana) • Brassica nigra –disturbed sites across North America • Hirschfeldia incana –disturbed sites in California, Oregon, Nevada •Only Brassica tournefortii is expanding into the desert (?) Distribution of Brassicas (Jepson) B. nigra B. tournefortii H. incana Distribution of Brassicas (Cal Flora) B. nigra H. incana B. tournefortii Biology of Brassica tournefortii •Winter annual •Basal rosette growth form until flowering •Seed dispersal by tumbling plant or dehiscent fruit (siliques) •Unknown— –Phenology –Germination physiology –Regulation of seed production –Seed longevity in seedbank –Effects on soil chemistry, toxicity B. tournefortii Germination •Wide temperature range –16-32 oC •Tolerates high salt concentration –Up to 1.58 dS/m •Light or darkness •After 10 wk under water (Bangle and Powell 2004 Mojave Desert Science Symposium) Brassica spp. Germination •Light or darkness •Species differences – B. tournefortii -100% germination –No differences between Riverside and Coachella B. tournefortii – B. nigra and H. incana -44 to 76% germination •Temperature responses (day/night oC) –Germ at 19/7 > germ at 23/9 > germ at 27/10 •Moisture responses –Germ at 0 bars > -1 bar > -5 bar B. tournefortii Seed Production (Trader and Brooks 2004 Mojave Desert Science Symposium) Road Effects on Biomass and Seed Production (Trader and Brooks 2004 Mojave Desert Science Symposium) Comparative Phenology •Pot experiments –Riverside, CA and Las Vegas, NV – B. tournefortii (inland and desert), B. nigra, H. incana –Quantify development, growth, life span, fecundity •Field experiment –Mojave Desert site – B. tournefortii and native annuals –Quantify development, growth survival, diversity B. B % t ou . % D t o B o f ese r o I urn n n P f e l l . tou a P a In f rt e nd o l n a f r ts or n t ii ts t l : ii and : 100 10 20 30 40 50 60 70 80 90 2 100 0 /1 10 20 30 40 50 60 70 80 90 7 0 r 2 2/17/2005 nefo /2 4 3 2/24/2005 /3 vs 3 3/3/2005 /1 0 . De 3 3/10/2005 r /1 7 t ii 3 3/17/2005 /2 4 3/24/2005 P 3 /3 1 s 3/31/2005 heno 4 e /7 4/7/2005 r 4 / 1 t 4 4/14/2005 4 /2 P 1 4/21/2005 l 4 opu /2 og 8 4/28/2005 5 /5 5/5/2005 y 5 /1 2 l 5/12/2005 at 5 i /1 n 9 d s P 5/19/2005 i i op g ff i 5 Se F B n / e 2 ons l s o P 6 o i r tt f 5/26/2005 l . w e ti i i ca ng ng n nt 6 e r o / ot 2 i ng n 6/2/2005 S t e t l ed 6 y / 9 6/9/2005 s 6 / 1 : 6 6/16/2005 6 /2 3 6/23/2005 Brassica Phenology in Pots: B. nigra H. incana vs. 100 90 % ofB P.l annigtsra 80 70 60 50 Bolting 40 Flowering 30 20 Setting Seed 10 0 2/17 2/24 3/3 100 3/10 90 H. incana 3/17 % of Plants 80 3/24 70 3/31 60 4/7 50 4/14 40 Bolting 4/21 30 4/28 Flowering 20 5/5 Setting Seed 10 5/12 0 5/19 2/17 5/26 2/24 6/2 3/3 6/9 3/10 6/16 3/17 6/23 3/24 3/31 4/7 4/14 4/21 4/28 5/5 5/12 5/19 5/26 6/2 6/9 6/16 6/23 Brassica Phenology in Pots: Rate of Cotyledon Loss in Brassica Species 100 90 80 B. tournefortii: 70 Desert 60 % Without B. tournefortii: Cotyledons 50 Inland 40 B. nigra 30 20 B. geniculata 10 0 7 4 /3 0 7 4 1 /7 4 1 8 /5 2 /1 /2 3 /1 /1 /2 /3 4 /1 /2 /2 5 /1 2 2 3 3 3 3 4 4 4 5 Brassica Phenology in Pots: Rate of Height Growth in Brassica Species 60 B. tournefortii Desert 50 B.tournefortii Inland 40 B. nigra Average Height B. geniculata 30 (cm) 20 10 0 7 4 /3 0 7 4 1 /7 4 1 8 /5 2 9 6 /2 /9 6 3 /1 /2 3 /1 /1 /2 /3 4 /1 /2 /2 5 /1 /1 /2 6 6 /1 /2 2 2 3 3 3 3 4 4 4 5 5 5 6 6 Brassica Phenology in Pots: Rate of Leaf Production in Brassica Species 25 B. tournefortii Desert 20 B.tournefortii Inland 15 B. nigra Average Leaf # B. geniculata 10 5 0 7 4 /3 0 7 4 1 /7 4 1 8 /5 2 9 6 /2 /9 6 3 /1 /2 3 /1 /1 /2 /3 4 /1 /2 /2 5 /1 /1 /2 6 6 /1 /2 2 2 3 3 3 3 4 4 4 5 5 5 6 6 Field Phenology Experiment Phenology of B. tournefortii and Native Species: B. tournefortii 100 90 Bolting Flowering 80 70 Seed Set Dispersal Brassica 60 tournefortii 50 % of Plants 40 30 20 10 0 8 /2 /7 2 7 2 7 /4 /9 4 9 4 9 /3 /8 3 8 3 /2 2 2 /1 /1 /2 /2 3 3 /1 /1 /2 /2 4 4 /1 /1 /2 1 2 2 2 2 3 3 3 3 4 4 4 Phenology of B. tournefortii and Native Species: Chaenactisstevioides 100 90 80 70 60 Chaenactis stevioides 50 % of Plants 40 30 Bolting Flowering Seed Set 20 10 0 8 /2 /7 2 7 2 7 /4 /9 4 9 4 9 /3 /8 3 8 3 /2 2 2 /1 /1 /2 /2 3 3 /1 /1 /2 /2 4 4 /1 /1 /2 1 2 2 2 2 3 3 3 3 4 4 4 Phenology of B. tournefortii and Native Species: Cryptanthaangustifolia 100 90 80 70 Bolting Flowering Seed Set Cryptantha 60 angustifolia 50 % of Plants 40 30 20 10 0 8 /2 /7 2 7 2 7 /4 /9 4 9 4 9 /3 /8 3 8 3 /2 2 2 /1 /1 /2 /2 3 3 /1 /1 /2 /2 4 4 /1 /1 /2 1 2 2 2 2 3 3 3 3 4 4 4 Rate of Height Growth in B. tournefortii and Native Species 35 30 25 Brassica tournefortii 20 Average Height (cm) Chaenactis stevioides 15 Cryptantha angustifolia 10 5 0 8 /4 1 8 5 /4 1 8 5 /1 /8 5 2 /2 2 /1 /1 /2 3 /1 /1 /2 4 4 /1 /2 1 2 2 2 3 3 3 4 4 Conclusions Photo—Mark Dimmitt, Arizona-Sonora Desert Museum).