Salvia hispanica cultivation is recent in Brazil and occurs in the off-season, when there is lower water availability in the soil. Water deficit is one of the abiotic factors that most limit germination for compromising the sequence of metabolic events that culminate with seedling emergence. Several attenuating substances have been used to mitigate the effects resulting from this stress and give higher tolerance to the species. Thus, the objective of this study was to evaluate the action of different agents as water stress attenuators in the germination and accumulation of organic compounds in S. hispanica seedlings. The treatments consisted of pre-soaking the seeds for 4 hours in salicylic acid (1 mM.L-1), gibberellic acid (0.4 mM.L-1), distilled water and control treatment (without soaking). The seeds were germinated at osmotic potentials of 0.0, -0.1, -0.2, -0.3 and -0.4 MPa, using PEG 6000 as an osmotic agent. The variables germination percentage, germination speed index, shoot and primary root lengths, total dry mass, proline, total soluble sugars and total free amino acids were analyzed. Salicylic acid and gibberellic acid led to the best results among the attenuators tested, increasing germination, length, dry mass and biochemical components of S. hispanica seedlings under water deficit. Therefore, salicylic and gibberellic acids are efficient in mitigating water stress in S. hispanica seeds up to the potential of -0.4 MPa.

Light regime and temperature on seed germination in Salvia hispanica L.

Sunflower is a species with multiple potentialities and its yield can be affected by the presence of soluble salts in the soil, which is common in arid, semi-arid and irrigated regions. The objective of this study was to evaluate the effect of hydropriming as inducer of salinity tolerance in seeds and seedlings of sunflower, hybrid MG305CP. The germination tests were set with four replicates of 50 seeds per treatment, maintained in germinator at 30 ºC for ten days. To simulate salinity, sodium chloride diluted in distilled water was used at electrical conductivities of 0 (control), 4, 8, 12 and 16 dS m^-1. On the tenth day, the number of normal seedlings was counted and the length and dry matter of shoots and roots were determined. Seedling fresh matter was used to determine the contents of total chlorophyll, total soluble sugars and proline. The experimental design was completely randomized, in a 2 x 5 factorial scheme (with and without hydropriming and five levels of salinity). Hydroprimed sunflower seeds showed greater vigor expression, with higher number of normal seedlings and faster germination.

This study aimed to evaluate the effect of physiological priming with salicylic acid on the mitigation of water and salt stresses on onion (Allium cepa L.) seeds. For this, seeds of onion, cultivar IPA 11, were soaked in salicylic acid solution (50 µM) for 24 h and placed to germinate at different water and saline potentials. For water stress, the experiment was conducted in a completely randomized design, in a 2 x 5 factorial scheme (salicylic acid with 0 and 50 µM and osmotic potentials of 0, -0.1, -0.2, -0.3, -0.4 MPa induced by polyethylene glycol 6000), with four repetitions of 50 seeds per plot. In salt stress, the adopted experimental design was completely randomized, with treatments distributed in a 2 x 4 factorial scheme (salicylic acid at concentrations of 0 and 50 µM and the osmotic potentials of 0, -0.3, -0.6 and -0.9 MPa induced by NaCl), in four repetitions of 50 seeds. For both experiments, germination, growth and accumulation of organic solutes were evaluated. Salicylic acid did not stimulate the germination of onion seeds in the absence of stress, but the application of 50 µM of salicylic acid increased the germination speed, growth and dry matter accumulation under conditions of water and salt stress. Onion plants were efficient in performing osmotic adjustment up to the potentials of -0.2 MPa induced by PEG 6000 under water stress and of -0.4 MPa induced by NaCl under salt stress.

Sementes de três lotes de melancia (Citrullus lanatus Schrad.), cv. Crimson Sweet, foram expostas a cinco potenciais osmóticos (0,0; -0,2; -0,4; -0,6 e -0,8MPa) utilizando-se substrato umedecido com soluções de NaCl, com objetivo de avaliar os efeitos de diferentes potenciais osmóticos de NaCl na germinação e no desenvolvimento de plântulas de melancia. Avaliaram-se a porcentagem de germinação, primeira contagem de germinação, porcentagem de plântulas anormais, comprimento da plântula e peso da massa seca da plântula. A análise dos resultados permitiu concluir que a diminuição progressiva do potencial osmótico de NaCl do substrato é prejudicial à germinação e, principalmente, ao desenvolvimento de plântulas; os efeitos se acentuam a partir do potencial osmótico -0,4MPa.