Seed Germination Characteristics of Selected Native Plants of the Lower Rio Grande Valley, Texas

Seed germination characteristics of selected native plants of the lower Rio Grande Valley, Texas

ROBINS. VORA

Experhnents were conducted to identity treatments that increased 58% with 45 minutes acid treatment of huisachillo (Acacia schaf- emergence of seeds of 24 woody plant species native to the lower fwri) seeds, and 87% with acid treatment for 15 to 90 minutes of Rio Grande Valley of southern Texas. Sulfuric acid (18.4M retama (Purkinsoniu uculeutu) seeds. Similarly, germination of H&04) scarification significantly hnxeased emergenceof buisachc rattlebush (Sesbania drummondii) seeds was improved by soaking (A cud& smul&i), bui~ebillo (A. scwm?ri), Texas ebony (Pithecel- in acid for up to 4 hours (Easton 1984). Acid scarification for 60 to lobiumflexicmde), tenam (P.palkns), tepeguaje (Leucaenapuhv- 90 minutes followed by cold scarification for 90 days produced best r&da), retama (porkinson& rrcrrlcou),and western soapberry results with western soapberry (Sapindus drummondii) seeds (Munson 1984). Seeds of other species, such as sugarberry (Celtis (Sapiudus &wnmlo II@); treatments such as soakhrg in disHBed water, gibberellic acid (0.3 or 1.4 mMol), or other scari5cation luevigata), might undergo periods of dormancy that can be broken techniques were not as effective as add. Fresh guajillo (A. be&n- by prechilling (Bonner 1974,1984). Fulbright et al. (1986a, b) used died’) seedr required no treatment, but g-month-old seeds had a combination of mechanical scarification, gibberellic acid, and heat/ chill treatments to obtain 62% germination of granjeno (Cel- higher emergence with add scarification. Texas ebony emergence was higher from lO-month-old seed treated with acid than from tis p&da) seeds; and gibberellic acid, moist prechilling for 2 fresh seeds. No pre-treatment seemed necessary for seeds of coral weeks, and storage for 8 months as methods of improving germination of anacua (Ehretia anacua) seeds. Alaniz and Everitt (1980) bean (&ythrina he&cur), Texas persimmon (Dio~yruv texana), obtained 40 to 60% germination of anacua seeds by soaking them sugarberry (Celt& kvigata), granjeno (C. pal&da), pigeon-berry in acid for 2 hours. The results, however, have not been tested in (l?iv&ra hum&), Texas baby-bonnets (Coursetia uxillariv), gua- greenhouse and field structures. jillo (A. bedmdkri), and lotebush (Zixiphus obtu#ol&). Results My objective was to develop or improve greenhouse germina- with blackbrush (A. rigid&), Wright’s acacia (A. wright& rattle- tion techniques for 24 native woody plant species (Table 1). Treat- bush (Sesbania drummondii), guayran (t&aiacum angust@- ments were based on known germination characteristics for seeds Hum), brad1 (Condi& hooker& elbowbush (Forestiera angust#o- of different taxanomic groups. For example, seeds from families Ho), and anacua (E1srctfcranacua) seeds were inconclusive. Plants known for hard seed coats, such as Mimosaceae and Fabaceae, of 16 woody species achieved mean heights of 25 cm in 45 to 150 were subjected to scarification treatments. A secondary objective days. was to document the length of time needed for the seedlings to Keywords: seed treatments, scaritication, brush reach 25 cm in height, which is desired for field planting. Less than 5% of the lower Rio Grande Valley of Texas remains in Methods native brushland (U.S. Fish and Wildlife Service 1983). These brush communities provide critical habitat for numerous animal Tests were conducted to determine if greenhouse emergence species. For this reason, the Texas Parks and Wildlife Department could be increased for these species (Table 1) using the following and the U.S. Fish and Wildlife Service are restoring native brush types of pre-sowing treatments: soaking in distilled water, soaking by planting native seeds and seedlings in formerly cultivated fields. in gibberellic acid (0.3 or 1.4 mMol), or in acid ( 18.4M HaSOd), and Propagation of native plants requires the development of proper other scarification techniques such as hot water, sandpaper and handling methods for seeds and seedlings. Previous research on rock tumblers. I also tested the combined effects of seed ripeness native plants of the lower Rio Grande Valley has been conducted in and acid treatment on Texas ebony emergence. Experiments were laboratory growth chambers, for example, fresh seeds of persim- done with seeds of various ages. mon (Diospyros texunu) germinated best (33 to 90%) without any Seed Collection and Processing treatment (Plowman and Munson 1983, Ever&t 1984). Everitt Seeds were collected from local stands of native brush, primarily (1983a) reported germination rates of 87 to 92% for guayacan the Santa Ana National Wildlife Refuge near Alamo, Texas, (Guaiacum angus~ifolium)and 66 to 77% with fresh seed of guajillo between 1984 and 1985. They were collected directly from plants (Acacia berlandieri). Many other legume species have hard seed with the exception of anacua and cedar elm (Ulmus crassifolia). coats, and acid treatments have been used to increase germination which were swept off the ground. Seeds of leguminous species were of these species. Alaniz and Everitt (1978) obtained best results extracted manually. Fruits of granjeno, sugarberry, bras& anaca- with Texas ebony (Pithecellobiumjlexicaule) by soaking seed in huita (Cordia boisseri), and elbow bush (Forestiera angustifolia) concentrated sulfuric acid (hereafter acid) for 30 to 45 minutes to were depulped for some treatments by rubbing manually against a get 80% germination. Maximum germination for huisache (Acuciu wire mesh. Western soapberry seeds were removed from shells smallit’) was 65% with acid treatment from 45 to 60 minutes (S&es (pericarps). Seeds were stored in paper sacks on shelves at room 1974). Everitt (1983a, b) obtained 86% germination by soaking temperature until 10 January 1985 and were stored in a refrigerator fresh blackbrush (Acacia rigidula) seeds in acid for 20 minutes, at 4O C after that date. Author was forest ecologist at Rio Grande Valley National Wildlife Refuge, Alamo, Texas. His present addnss is U.S. Forest Service, 11704th Avenue South, Park Falls, Experimental Design, Treatments, and Propagation Procedures Wisconsin 54552. A randomized block design was used. Basic treatment types are The author thanks R. Schumacher for his suggestions on experimental treatments; 2. Labus, R. Florcs, V. Pulaski, T. High, and E. Couch for their assistance with listed in Table 2. Cedar elm fruits were planted in mulch collected grecnhousc work; J. Mcsscrly for the analyses of variance tests, and J. Young, J. from under the tree. Several unsuccessful exploratory treatments Eve&t, 0. Van Auken, Y. Wang, T. Fulbright, F. Banner, R. Lonard, M. Hecp, C. Halvorson, and N. Wells for the%editorial &estions. are not described in detail for sake of brevity. With the exception of Manuscript accepted 8 August 1988.

36 JOURNAL OF RANGE MANAGEMENT 42(l), January 1989 Table 1. Speciea selected for seed germination exparbnentr. shade cloth, light intensity varied at each table, and ran from about 300 pmolm-*s-‘(18% of external) to 600 ~mohn”i Yd(36% of external at mid-afternoon during several measurements in June Family Scientific name Common name 1986. Ulmaccae Celtispallida Granjeno During both years, the plants were watered once every other day Celtis laevigata Sugarberry for 5 minutes with overhead spray stick sprinklers. Sodium and Ulmus crassvolia Gzdar elm calcium concentrations in samples of the water supply (March Phytolaccaceae Rivina humilis Pigeon-berry Mimosaceae Acacia rig&&da Blackbrush 1985, July and August 1986) varied from 265 to 281 mg/ 1,and 45 to Acacio berlandien’ Guajillo 97 mg/l, respectively, with total salts estimated at 1,128 to 1,289 Acacia smallii Huisache mg/l. Two grams of slow-release fertilizer (18-7-10 + 1% Fe) were Acacia schaffneri Huisachillo placed on the soil surface when seedlings were about 5 cm tall. Pithecellobium pallens TCnaZa Pithecellobiumjlexicaule Texas ebony Data Analyses Luecaem pulverulenta Tepcguaje Analyses of variance (ANOVA) and Tukey’s HSD multiple Acacia wrightii Wright’s acacia comparison tests were used to identify significantly different Caesalpinaceae Parkinsonia aculeata Retama (m.05) treatment means, unless emergence was highest under no Fabacutc Erythrim herbacea Coral bean treatment. Multiple comparison tests were not used to compare Sesbania drummondii Rattlebush CourSeria axilkaris Texas baby-bonnets graded levels of acid treatment (Petersen 1977). Zygophyllaceac Guaiocum angustifolium Guayacan Sapindaceac Sapindus drummondii Western soapberry Results Rhamnaceae Condolia hooken’ Brasil Zisiphus obtusifolia Lotebush Germination of Fandlies EbelU_C Diospyros texam Texas persimmon Ulmaceae OleaCeaC Forestiera angustifolia Elbowbush Highest emergence of sugarberry occurred with pretreatment of Boraginaceae Cordia boisseri Anacahuita depulped seeds (Table 3). With granjeno, emergence was higher if Ehretia amcua the pulp was not removed (Table 3). There was no enhancement of emergence from soaking seeds of these 2 species in 1.4 mMo1 granjeno, additional treatments were not tried if emergence gibberellic acid for 5 hours. exceeded 75% with no treatment. Emergence counts were made Emergence rates of cedar elm were low (

JOURNAL OF RANGE MANAGEMENT 42(l), January 1980 37 Table 3. Emergenec (86) In respome to presowiq trdumts.

seed Days after Dist. water Gibb. acid (mMo1) Acid SDccieS COB. SOW sow ’ Control soak 0.3 1.4 SCUifiC.~ Other days Emergence (%) AtUlCUa 7-86 173 22b 27ab(4h) 3WW 16b(135m) Blackbrush s-85 23 24 19 24 27( Urn) 33(acid lSm+water 5h)’ Coral bean 7-84 6-85 62 50 29 37 Wm) Granjeno with PdP 8-86 8-86 19 77a 79a(5h) <33b(depulped) Guajillo 6-85 6-85 13 96 Wm) Guajillo 11-85 6-86 13 29b 38ab(5h) fi(lm) Huisache 7-85 5-86 46 llb 14b(6h) 95a(9Om) lOb(boil water) Huisachiio 10-85 7-86 42 2b 73412Om) Battlebush 7-84 6-85 34 12 11 12 14(2m) 1l(sandpaper 2m) Retama 7-86 10-86 7 8b 8b(4h) 51a(45m) Sugarberry depmptd 7-86 8-86 73a 58b(5h) 63ab(Sh) 63ab(Sh) a9b(with pulp) TCtUZa 7-84 6-85 25a 2Oa(‘lh) 28(7h) 42a(2m) 24a(samh.vr 2m) Tellam 7-84 10-86 Ob 45a( IOm) Tepeguaje 7-84 3-85 5b 13ab(2m) 28a(boil water) Tepeguaje 7-85 10-85 33b 37b(6h) 34b(6h) 82a(lonQ 5Ob(boil water) Tepeguaje 7-85 26b 73a(lOm) 84 (acid 15m) T. baby-bonnet 5-85 z 25 12 11 T. ebony 8-85 Sb(4h) 29ab(rock 5m) 11-85 3b 6bf6h). I 4b(4h) 78avOm) T. ebony 8-85 6-86 64b 88a(3Om) T. persimmon 7-84 3-85 55ab 72a(5Oh) 22bc(49h) 7Oa(lm) 77a(saudpaper 2m) T. persimmon 7-84 6-86 36 F) 33(3h) 34(lm) 28(boii water) W. acacia 7-84 3-85 13 27( lm) 29(sandpaper 2m) INumberof dsys after sowing that cumulativeeme nce data are presented. *h = hours; m = minutes; treatment mcsns followed Y?y the same letter (within row) wcm not &niticanUy different (p>o.Os). ~Emergcnce less when followed by soaking in di&llcd water, except blackbruah aa noted. ‘Blackbrush 8ecds rubbed lightly with coarse aandpapcr for 2 minutea had 25%emergence.

Table 4. Emergence (%) In response to pre-sowiug a&l (ISAM (HOSOS)treatment of seeds.

seed Days Concentrated sulfuric acid (minutes) after Sp&S Coll. Sown sowt 0 1 2 5 10 15 20 30 45 60 75 90 105 120 135 180

days % emergence Huisache 7-85 5-86 46 I1 26 44 92 80 95 94 97 Huisachiio l&85 7-86 42 2 4 58 73 Retama 7-86 10-86 7 2: 42 35 :: z 40 TCtUXa 7-84 6-85 23 TenaZa 7-84 IO-86 10 0 1 4 39 45 32 Tepeguajc 7-84 3-85 81 Tcpcguaje 7-85 l&85 90 3: 24 :: 72 82 Tepeguaje 7-85 6-86 41 26 56 73 84 78 73 74 T. ebony 8-85 11-85 40 3 67 71 78 T. ebony 8-85 6-86 66 64 88 T. persimmon 7-84 3-85 68 T. persimmon 7-84 6-86 34 :: 7034 27 25 19 w. soapberry IO-85 6-86 57 17 67 70 47 71 69 ‘Number of days after sowing that cumulative emergence data arc prcacnted.

(Table 3). Soaking 9-month-old tepeguaje (Luecuenu pulveru- Caesalpinaceae Zenfu)seeds in water brought to boiling temperature and cooled for Emergence of retama seedlings was higher (KO.05) with acid 48 hours, increased emergence from 5% for the control to 28%. In a treatment of 45 minutes (51% instead of 8%for the control) (Tables subsequent experiment, soaking 3-month-old seeds in acid for 10 3 and 4). minutes increased emergence from 33% for the control to 82%. Fabaceae This treatment produced better results than boiling water or 2 Acid scarification did not significantly (KO.05) increase emer- minutes in acid (KO.01) (Tables 3,4). In a later experiment with gence of seeds tested of this legume family. Emergence from 1 l-month-old seeds, best results were with acid treatment for 15 untreated seed was 25% for Texas baby-bonnets (Coursetiaaxilla- minutes (Table 4).

39 JOURNAL OF RANGE MANAGEMENT 42(l), January 1999 Table 5. Effect of wed-ripenew and add treatment on Tcru ebony Table 6. Time (day) till mean wedlhg height of 5.10 and 25 cm1for 16 emergence. speck (- iadkates not measured).

Seed age Pod color Treatment Mean cmergenal Date Height (cm) % Species planted 5 10 25 10 months Brown Acid 30 min 10 months Brown No treatment : Blackbrush Jun 85 -aai40 <1 month Green No treatment 48 Coral bean Jun 85 - 18 73 Cl month Green Acid 30 min 35 Granjeno Aug 86 - - 70 ‘Treatment means were all significantly different (KO.05) from other treatment Guajillo Jun 85 8 18 !I0 means. Guaiacan May 85 10 - - Huisache May 86 - - 52 ris). 12% for rattlebush, and 50% for coral bean (Eryrhrina herba- Huisachillo Jul86 - - 80 ceo) (Table 3). Rattlebush Jun 85 20 45 - Zygophyllaceae Sugarberry Jun 85 TI 702 Tenaza Jun 85 15 90 Soaking IO-month-old seeds of guayacan in distilled water for Tepeguaje Mar 85 45 z 80 3.5 hours produced twice the number of seedlings compared to T. baby bonnets Jun 85 25 40 150 untreated seeds. Emergence was low (6 to 12%). Emergence was Texas ebony Aug 85 - - 90 34% with 250 untreated 2-month-old seed planted in September T. persimmon Mar 85 80 100 150 1986. W.-soapberry Jun 86 - - 80 Wright’s acacia Mar 85 18 40 70 Sapindaceae lEstimated by interpolation bccatue aceding heights were not measured daily. Acid scarification for 45 minutes or more significantly (m.05) *S&a sown m August 1986 producedplants with mean height of 40 cm in 77 days. increased emergence of western soapberry (Table 4). Highest emergence (71%) was with acid scarification for 120 minutes. Cold Discussion stratification for 90 days (Munson 1984) did not increase emergence (e.g., 60 minutes acid-70%, with pre-stratification-57%). No treatment seemed necessary for fresh seeds of sugarberry Rhamanaceae (depulped), granjeno (whole fruit), lotebush (depulped), pigeon- berry (whole fruit), or IO-month-old coral bean seeds. The first 4 Mean emergence was 95% in 3 trials with fresh, depulped seed of drupe-producing species are thought to be some of the most impor- lotebush (Ziziphus obtusifolia). Results were poor (emergence tant wildlife food plants. Results with depulped granjeno seeds

JOURNAL OF RANGE MANAGEMENT 42(l), January 1999 39 lengthier soak of 4 hours recommended by Easton (1984) was not was obtained with Texas ebony, huisache, huisachillo, tepeguaje, evaluated. Results with fresh guajillo seeds were similar to those of coral bean, western soapberry, Texas persimmon, and anacahuita. Everitt (1983a) (no treatment was necessary), but acid treatment Storage techniques must be developed for other species if seeds are for 1 minute increased emergence (KO.05) of 5-month-old seed. to be collected in the summer and not planted in fields until fall and This suggested that the seed coat of guajillo might harden with winter during cooler and wetter conditions. time. Emergence of Texas baby bonnets was low (25%) and further experimentation is needed with that species, especially since it is Literature Cited considered a rare plant (Lonard et al. 1989). Alaniz, M.A., and J.H. Eve&t. 1978. Germinationof Texas ebony seeds. J. Everitt (1984) stated that fresh seeds of Texas persimmon germi- Rio Grande Valley Hortic. Sot. 32~95-100. nated well without treatment, and viability was not reduced after Ahniz, M.A., 8nd J.H. Eve&t. 19M). Germination of anacua seeds. J. Rio Grande Valley Hortic. Sot. 3475-80. storage under room conditions for 2 years. Mild scarification and BOMW, F.T. 1974. Celtis L. Hackberry. p. 411-416. In: Seeds of woody soaking in distilled water had positive effects on emergence of plants in the United States. USDA Agr. Handb. No. 450. Washington._ I-month-old seeds, and no treatment was necessary with 23- D.C. month-old seeds (Tables 3 and 4). Emergence of untreated seeds Banner, F.T. 19M. Germination test for,sugarberry (Celris laevigata dropped by 35% over that period suggesting loss of viability. Willd.). Newsletter Assoc. official Seed Analysts 58324-26. Low emergence was obtained for cedar elm, guayacan, anacua, Easton, E.F. 19g4. Drummond rattlebox (Sesbania dnunmondii)gcrmins- tion as intluencd by scarification, temperature, and seeding depth. Weed bras& and elbowbush, and further experimentation is needed with Sci. 32223-225. these species. Emergence results with guayacan and anacua were Eve&t, J.H. 198L. Seed germination characteristics of 3 woody plant much lower than that obtained in some laboratory germination sc&es from south Texas. J. Range Manage. 36246-249. tests (Alaniz and Everitt 1980, Everitt 1983a). Fulbright et al. E&t, J.H. 198313.Seed germination chara&eristics of 2 woody legumes (1986a) did not obtain superior germination of anacua seeds with (retama and twisted acacia) from south Texas. J. Range Manage. acid scarification as did Alaniz and Everitt (1980), and plant grow- 36:411414. Ever&t, J.H. 1984. Germination of Texas persimmon seed. J. Range Man- ers have reported mixed results (pers. commun.). Anacua, bras& age. 36:411-414. and elbowbush seem to have complex dormancy mechanisms that Eve&, J.H., A.H. Gerbermann, and J.A. Cuellar. 1977. Distinguishing need to be identified. Cedar elm seeds appear to have very low saline from non-saline rangelands with skylab imagery. Photogrammet- viability, and time of collection and sowing are probably important. ric Engineering and Remote Sensing 43:1041-1047. Many growers have reported trouble growing anacahuita (pers. Fulbright, T.E., K.S. Fhnikcn, and C.L. Waggerman. 191160.Methods of commun.). My results with depulped 1 l-month old seed were good enhancing germination of anacua seeds. J. Range Manage. 39:450-453. Fulbrlght, T.E., KS Flemdken, and G.L. Waggerman. 198613.Enhancing (70%), although the sample size of 30 was small. Anacahuita seeds germination by spiny hackberry seeds. J. Range Manage. 39:552-554. might have immature embryos when the fruits fast drop and may Kirk, R.E. 1982. Experimental design: Procedures for the behavioral scien- require a long period of after-ripening before germination can ces. 2 ed. Brooks/Cole Publ. Co. occur. Lonard, RI., J.H. Everitt, and F.W. Judd. 1989. Woody Plants of the Several species, such as lotebush, might germinate readily at Lower Rio Grande Valley, Texas. N.A. Browne, illustrator. Texas seed drop, but if stored or if conditions are otherwise unfavorable, Memorial Museum Press. Austin. Tex. (In mess). may undergo dormancy for an extended period. Other researchers Martin, R.E., R.L. Miller, a& C.T. &shwi. lb75. &mination respondes of lermme seeds sub&ted to moist and dry heat. Ecology 56:1441-1445._ .-. (J. Everitt, pers. commun.) have had low success growing lotebush Mum&. R.H. 1984.-Germination of we&m soap&r@ as affected bv from stored seed. Seed viability may also differ considerably from scarification and stratification. HortScience 19:7i2-713. plant to plant with some of these species. Nokes. J. 191)6. How to grow native plants of Texas and the Southwest...-_-. The salinity of the water in the greenhouse was a concern Tek Monthly Press, Austin, Tex&. because salts can stunt seedling growth (Eve&t et al. 1977, Salis- Petersen, R.C. 1977. Use and misuse of multiple comparison procedures. bury and Ross 1985). Laboratory experiments, however, indicate Agron. J. 69~205-208. Plowman, R.D., and R.H. Munsoa. 19(13. Seed dormancy in Texas ner- many plants of the Lower Rio Grande Valley have high tolerances simmon (Dimpyros texana Scheele). Plant Propagator 29: M-15. c -_ of salts before germination is reduced significantly, varying from Sallmbury, F.B., and C.W. Ross. 19115. Plant physiology. 3rd edition. 2,000 mg/ 1 for guajillo to more than 10,000 mg/ 1 for blackbrush Wadsworth Publ. Co., Inc., Belmont, Calii. (Ever&t 1983a). Salts might accumulate to toxic levels if plants are Se&es, C.J. 1974. Salient aspects of huisache seed germination. Southwest. stored in the greenhouse for long periods without flushing by rain. Natur. 18:383-392. U.S. Flsb and Wildlife Service. 1983. Land protection plan: Lower Rio In general, highest emergence was achieved with fresh, mature Grande Valley National Wildlife Refuge. U.S. Fish Bt Wildlife Serv., seeds. With 8- to IO-month-old seeds, 50% and better emergence Albuquerque, N. Mex.

40 JOURNAL OF RANGE MANAGEMENT 42(l), January 1989