Restoration of nodosa (Uchria) Ascherson prairies through seed propagation. Seed storage and growth of seedlings as affected by inorganic nutrients and hormones. 1 Universidad de Las Palmas de Gran Canaria M. Zarranz Elso 1, 2, N. González Henríquez 2, P. García-Jiménez 1, RR. Robaina 1 2 Instituto Canario de Ciencias Marinas

In the frame of the restoration of natural populations of Cymodocea nodosa of the , seeds are being collected at natural populations where germination is rather scarce and seasonal after dormancy. We have developed techniques of propagation in vitro of collected seeds, consisting in forced seed germination and seedlings propagation to obtain mature 20-30 cm plantlet, which eventually are being used for restoration. In order to improve the developed methodology, several experiments were conducted to adjust conditions for seed storage under different regimes of temperature without loosing germinative potential, fertilize during propagation with controlled released NPK fertilizers, and increase growth by dipping seedlings in solutions of the most common plant hormones.

I) SEED STORAGE II) THE EFFECTS OF PLANT III) THE EFFECTS OF A LONG- GROWTH REGULATORS LASTING FERTILIZER The seeds used in all the experiments described in this study were collected through SCUBA diving in a C. nodosa The seeds (ca 400) were germinated and the resulting The seeds were germinated as described in Zarranz et al. prairie located at Juan Grande in the southeast coast of Gran plantlets were cultivated 15 d after 3 h dipping in autoclaved 2008 (ISWB8)(1), and the resulting plantlets were cultivated 30 d Canaria (27º 48′ 00″ N; 15º 25′ 40″ W). Seeds were surface seawater containing 0 (control), 10-4 or 10-6M of the auxins in aquaria (30 L) with a sand layer in which the plantlets were sterilized, germinated and the resulting plantlets were IAA, NAA, 2-4D, cytokinin BA, and gibberelin GA3 (n= 30 in cultivated around NPK fertilizers bars (12%N, 6%P2O5, cultivated using the methods described elsewhere (1). each treatment in two set of experiments). Culture medium was 9%K2O) (Figure). A control aquaria was arranged in which For the experiments concerning storage, seeds (ca. replenished after 15 days, and dipping of the plantlets in plantlets were located the same as in fertilized aquaria, but 2500) were stored at 4 ºC, 18 ºC and room temperature both hormone solutions repeated. Leaf and root growth and emission without any bar. Conditions were RT and average 60 µmol in dry conditions or submerged in autoclaved seawater rates were recorded at day 30 after the first dipping. photons m-2 s-1. Samples of interstitial water in the sand and (Figures). Each month 30 seeds were transferred to culture were analyzed for ion compositions by ICP spectroscopy vessels to check for their germinative potential. RESULTS AND DISCUSSION and CHN elemental analyzer. Complementarily, seeds were collected the same month and cultivated in the laboratory to compare with their potential in No significant differences were obtained when leaf the nature. The percentage of germinating seeds was recorded. growth rates are compared to control conditions except for the

highest concentration of GA3. As opposite, inhibitory effect was recorded in certain treatments.

Leaf growth Leaf growth 0,34 0,38

0,32 (b) 0,36 0,30

(a) 0,28 RESULTS AND DISCUSSION

0,34

-1 0,26 -1 (a,b)

(a) cm d 0,24 cm d (a) (a) 0,32 (a) (a) The addition of long lasting NPK fertilizers bars to the RESULTS AND DISCUSSION 0,22 (a) (a) 0,20 (a) 0,30 sand where plantlets were grounded, clearly affected ion 0,18

Seeds stored in dry conditions failed to germinate. The 0,28 0,16 compositions of the surrounding sand, thus increasing N and P CONTROL NAA 10-6M NAA 10-4M IAA 10-6M IAA 10-4M CONTROL GA3 10-4M GA3 10-6M BA 10-4M BA 10-6M 2,4-D 10-6M figures show the germinative potential of seeds stored in wet contents. In spite that not dramatic changes were observed in ion Shoot emision Shoot emision conditions at different temperatures (Fig. A, B). The results 0,030 0,030 composition of the treated plantlets (Table), a significant (a) (a) 0,025 0,025 obtained with seeds collected each month and germinated in (a) increase in root growth rate was observed in fertilized plants. (a,b) 0,020 0,020 (a) -1 vitro are shown in Fig. C. (a,b) -1 0,015 0,015 (a) (a) shoot d shoot shoot d shoot

0,010 (b) (b) 0,010 (a)

RT Storage AB0,005 0,005 Non Fertilized Temperature-controlled Storage 0,4 (a) Fertilized 100 (a) Sediment Fertlization 100 0,000 (a) 4 Phase I Phase II 0,000 (a) CONTROL GA3 10-4M GA3 10-6M BA 10-4M BA 10-6M 2,4-D 10-6M CONTROL NAA 10-6M NAA 10-4M IAA 10-6M IAA 10-4M Phase I Phase II N 10cm 80 80 0,3 N 15 cm 3 P 10 cm 18ºC P 15 cm 60 60 Root growth Root growth 0,16 0,09 0,2 2 Growth Rates

40 /l 40

0,14 0,08 mg % Germination % 20 Germination% (a) 1 20 4ºC (a) (b) (a) (a) (a) 0,1 0,12 0,07 (a) (a) 0 0 (a,b) 0 -1 -1 (a) (a) 0,10 0,06 (a) (a) cm d (b) cm d 0,0 NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEPT OCT NOV. NOV DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT (a) Leaf Growth Root Growth Root Emision Leaf Emision Shoot Emision 0,08 0,05 (a) t0 t10 t20 t30 (c)

0,06 0,04 100 C 0,04 0,03 day 30 day 30 Phase I Phase II Phase III day 0 CONTROL NAA 10-6M NAA 10-4M IAA 10-6M IAA 10-4M CONTROL GA3 10-4M GA3 10-6M BA 10-4M BA 10-6M 2,4-D 10-6M Non fertilized Fertilized 80 mg dry weight (n = 30, 25, 26) 21.37 ± 1.26 (a) 33.27 ± 2.01 (b) 49.32 ± 3.57(c) Root Emision (a) (b) (c) 0,12 Root Emision P total (%) (n = 3, 6, 6) 0.53 ± 0.013 0.36± 0.019 0.28 ± 0.004 0,12 (a) (b) (c) 60 N total (%) (n = 6, 12, 12) 4.27 ± 0.137 2.78 ± 0.101 1.83 ± 0.044 0,11 (a) (a) (a) (a) 0,11 C total (%) (n = 6, 12, 12) 35.06 ± 0.28 34.50 ± 0.31 34.09 ± 0.33 (a) (a) (a) (a) (a) (a) (b) 0,10 N/P (n = 3, 6, 6) 7.98 ± 0.19 7.80 ± 0.24 6.43± 0.19 0,10 40 (a,b) (a) (b) (c)

% Germination % (a,b) C/P (n = 3, 6, 6) 65.47 ± 1.71 97.72 ±4.84 119.99 ±2.35 0,09 -1 (a) (b) (c)

1 0,09 - C/N (n = 6, 12, 12) 8.23 ± 0.26 12.57 ± 0.39 18.74 ± 0.47 (b) (a) (a) (b)

20 d root 0,08 K % (n = 3, 6, 6) 3.30 ±0.14 3.64 ±0.09 4.40±0.08 root d root 0,08 (a) (b) (b) (b) Na % (n = 3, 6, 6) 3.25 ± 0.13 3.75 ± 0.06 3.67 ± 0.09 0,07 (b) (b) 0,07 (a) (a) (a) 0 Ca% (n = 3, 6, 6) 0.65 ± 0.09 0.57 ± 0.04 0.61 ± 0.03 NOV DEC JAN FEB MAR APR MAI JUN JUL AUG SEP OCT NOV. 0,06 (a) (a,b) (b) 0,06 S % (n = 3, 6, 6) 0.42 ± 0.02 0.37 ± 0.01 0.34 ± 0.007

(a) (a) (a) 0,05 Mg % (n = 3, 6, 6) 0.67 ± 0.05 0.70 ± 0.02 0.71 ± 0.01 CONTROL GA3 10-4M GA3 10-6M BA 10-4M BA 10-6M 2,4-D 10-6M 0,05 CONTROL NAA 10-6M NAA 10-4M IAA 10-6M IAA 10-4M Mn (ppm) (n = 3, 6, 6) 454.75 ± 48.90 (a) 118.74 ± 26.73 (b) 116.63 ±13.55 (b) Records of seed germination and plantlet formation in Zn (ppm) (n = 3, 6, 6) 34.71 ± 2.07 (a) 106.06 ± 2.60 (b) 71.25 ± 1.97 (c) natural populations of C nodosa clearly show that rather low B (ppm) (n = 3, 6, 6) 286.10 ± 14.40 (a) 260.33 ± 9.95 (a,b) 238.18 ±4.45 (b) Plant hormones control growth and development in higher Cu (ppm) (n = 3, 6, 6) 19.80 ± 5.51 (a) 16.32 ± 0.87 (a) 10.63 ± 0.26 (b) percentage of new plantlets are recruited yearly, thus Fe (ppm) (n = 3, 6, 6) 239.07 ± 22.02 (a,b) 177.44± 14.56 (b) 247.96 ± 20.98 (a) A plants, therefore the rationale for the performed experiments is suggesting that mainly vegetative propagation support for that, when treated with hormone, the plantlet may achieve better (2,3,4,5,6,7) The effects of fertilizers have received attention in the past growth and maintenance of the prairies . development and higher rates of vegetative growth and vigour to investigate nutritional traits in . Most of the Therefore, it is assumed that the techniques for in vitro that could improve acclimation, and particularly transplanting. research has been done in the nature thus producing germination and transplanting may contribute to increase these Common practice in vitro is the addition of the regulator to controversial results that could be attributed to variable potentialities, particularly if germplasm could be stored and the medium, where aseptic conditions prevent from any conditions (19, 20, 21, 22, 23, 24). Doubtless more stable conditions are used when and wherever required. The results obtained clearly chemical modification of the regulator supplemented. Dipping to be encountered in our experiments than in the nature. shows that C nodosa seeds are recalcitrant to storage, and that into hormones is alternatively used when non aseptic conditions Even in such conditions, plantlets obtained in vitro were the records in the best conditions in the laboratory did not and plantlets are being used, assuming that, more restricted, but apparently unaffected significantly in their ion composition. The exceed significantly the records obtained with seeds collected benefits could be still obtained from the exogenous and rapid in the natural populations. Recalcitrance seems to be common N/P, C/N or C/P ratios revealed that in vitro derived plantlets are effect of the hormone. To the objectives pursued, only GA3 (8, 9, 10, 11, 12, 13, 14, 15, 16) far from starved (25), thus restricting significant nutrient uptake to most of seagrasses , thus restricting apparently affected leaf growth rate significantly, being the in the whole plantlets, but concentrating their effect on root germplasm conservation in vitro. In the case of seagrasses, others ineffective or even inhibitory. emission which was higher in fertilized plantlets. Broadly, such as C nodosa, which forms seeds banks in the natural The use of plant growth regulators have been documented fertilization of plantlets during acclimatation was apparently meadows, the efficiency of the techniques to induce in culture of marine seagrasses. Our results agree with previous germination in vitro with conservation of seeds directly in situ (17,18) ineffective. report on the effects of GA3 on marine plants , therefore it could be an appropriate combination. should be further explored.

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