Resumen

GARCIA, M.D; PESQUEIRA, J  y  OTONDO, J. Pureza física y germinación de cariopses de Chloris gayana Kunth y Panicumcoloratum L. cosechados de plantas cultivadas en un suelo alcalino-sódico. RIA. Rev. investig. agropecu. [online]. 2018, vol.44, n.1, pp.84-91. ISSN 1669-2314.

The objective of the study was to evaluate physical purity, germination percentage (G) and germination velocity (GV) of caryopses of Chloris gayana cv. Finecut (Cg) and Panicum coloratum cv. Klein Verde (Pc) collected from plants grown in an alkaline-sodic soil (pH = 9.8, ECe = 0.69 dS m^-1, EPS = 26.2%). To compare G of both species, 50 caryopses (n = 5) were incubated in deionized water. To evaluate G responses to salinity and alkalinity, an experiment with completely randomized design and factorial structure (n = 4) of two species x four concentrations of Na+-salts (25, 50, 100 and 150 mM) x two pHs (6 and 10) was performed. Treatments consisted in combinations 1:1 of NaCl + SO4Na (pH = 6) and Na2CO3+ NaHCO3 (pH = 10): 25mMpH6 (control); 25mM-pH10; 50mM-pH6; 50 mM-pH10; 100mM-pH6; 100mM-pH10; 150mM-pH6 and 150mMpH10. Samples of the natural-dispersal material from panicles of Cg and Pc contained (mean ± SEM; % of total weight): caryopses covered by glumes (53 ± 2.6; 41.3 ± 4.6), isolated caryopses (1.4 ± 0.6; 10.3 ± 1.95), empty caryopses (32.9 ± 2.4; 22.7 ± 2.4) and inert materials (12.5 ± 2.2; 25.7 ± 2.1). Caryopses of Cg and Pc incubated in water showed similar values (mean ± SEM, in %) of G (96.5 ± 2.4 and 89.2 ± 3.6) and GV (54.7 ± 7and 51.7 ± 5.5). In the presence of salt 25 mM, the increment of pH from 6 to 10 did not inhibit G of Cg (94.4 ± 2.55 and 90.7 ± 3.7) or Pc (93.9 ± 2.2 and 92.95 ± 1.9). Incubation in 50mM-pH=10 inhibited G of Pc (33.2 ± 4.7) but not G of Cg (93.5 ± 3.3). The solution 100mM-pH=10 inhibited more the germination of Pc (2.5 ± 1.5) than that of Cg (66.35 ± 5.5), and 150mM-pH10 strongly inhibited germination of both species, Cg (3.5 ± 1.5) and Pc (0 ± 0). In solutions with pH = 6, the G of Cg and Pc was not affected up to 100 mM of salt, but 150 mM inuduced decreases of 25 % and 20 % of G, respectively, in relation to that observed in 25mM-pH=6. The increment of pH also affected more GV of Pc than that of Cg. GV of both species responded in a similar way to increases of salinity in neutral (pH = 6) solutions. The GV of the caryopses incubated in 50mM-pH=6 did not differ from their respective controls. From 50 mM, each increase of salt concentration induced the decrease of GV of both species, relative to their respective controls.

Palabras clave : Salinity; Alkalinity; Megathermic forage poaceae; Germination velocity.

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