Response of Ornamental Sunflower Cultivars ‘Sunbeam’ and ‘Moonbright’ to Irrigation With Saline Wastewaters

Abstract

2 To explore the possibility that saline wastewaters may be used to grow commercially acceptable floriculture crops, a study was initiated to determine the effects of salinity on two pollen-free cultivars of ornamental sunflower (Helianthus annuus L.). 'Moonbright' and 'Sunbeam' were grown in greenhouse sand cultures irrigated with waters prepared to simulate wastewaters commonly present in two inland valley regions of California: 1) San Joaquin Valley (SJV) where saline-sodic drainage waters are dominated by sodium (Na + ) and sulfate (SO 2− 4 ) and 2) Coachella Valley (CV) where major ions in tailwaters are Na, predominating in that order. Ten-day-old seedlings were subjected to five salinity treatments of each water composition, each replicated three times. Electrical conductivities (EC) of the irrigation waters were 2.5, 5, 10, 15, and 20 dS·m −1 . Flowering stems were harvested when about 75% of the ray flowers were nearly horizontal. Stem length and fresh weight, flower and stem diameter were measured. Mineral ion concentrations in upper and lower stems, upper and lower leaves were determined. Sodium was excluded from the young tissues in the upper portions of the shoot and retained in the basal stem tissue. Inasmuch as sunflower is also a strong potassium (K)-accumulator, K + /Na + selectivity coefficients were unusually high in the younger shoot organs. Despite a fivefold increase in substrate Ca 2+ in both solutions, shoot-Ca decreased as salinity increased and this cation was retained in the older leaves. A few of the lower leaves of plants irrigated with ICV waters at EC = 10 dS·m −1 and higher, exhibited necrotic margins which were undoubtedly caused by high concentrations of Cl − in the tissues. Flowering stems produced in all treatments met florist quality standards in terms of diameters for stems (0.5 to 1.5 cm) and blooms (8 to 15 cm). Across treatments, stem lengths ranged from 60 to 175 cm. Both ornamental sunflower cultivars proved to be good candidates for production of marketable flowering stems using moderately saline wastewaters.

Produção de girassol ornamental com uso de águas salobras em sistema hidropônico NFT

“…Em relação à resposta de genótipos de interesse ornamental, Grieve & Poss (2010) , sobre a produção de dois genótipos de girassol, reportando que ambos os genótipos têm potencial para o mercado de flores quando produzidas com águas moderadamente salinas. Esses autores observaram a presença de margens foliares necróticas, atribuídas ao cloreto, mas apenas para poucas plantas produzidas com salinidade da água acima de 10 dS m -1 .…”

Production of ornamental sunflower irrigated with oilfield produced water in the Brazilian semiarid region

“…In subsequent cycles, this type of water also led to a significant accumulation of Na in the roots, particularly in relation to the use of PWO. The accumulation of Na in the lower parts of the plants had been reported in relation to ornamental sunflower 'Moonbright' irrigated with saline water (Grieve & Poss, 2010). Furthermore, during the last production cycle, the use of PWF resulted in a reduction of Mg content in the aerial parts, and in an increase of K content in the roots and aerial parts of the plants, particularly in comparison to the treatment with GW.…”

“…of K fertilization has been suggested for sunflower plants grown under salt stress (Grieve & Poss, 2010), but there are also relationships between nutrients that may affect the growth of sunflower plants, as shown by Sousa et al (2016). The concentrations of Ca, Fe, and Zn in the roots were positively affected by irrigation with PWO, during the second cycle (Table 6), in comparison to the treatment with PWF.…”

“…In turn, ornamental sunflower crops of 'Moonbright' and 'Sunbeam' tolerate water with up to 10.9 dS m -1 conductivity (Grieve & Poss, 2010). Furthermore, Maciel et al (2012) observed the same commercial value for stems of 'Red Sun' sunflower grown in hydroponic solution up to 16.36 dS m -1 .…”

Substratos e tempo de renovação da água residuária no crescimento do girassol ornamental em sistema semi-hidroponia

“…O valor médio do DH para as plantas sob manejo de renovação/substituição da AR a cada quatro dias, foi da ordem de 9,5 mm, valores esses inferiores aos observadas por Biscaro et al (2008) nesta fase do crescimento da planta; apesar disto, os valores obtidos no presente experimento, independente do tratamento, estão dentro do intervalo dos limites de 5 a 15 mm, indicados como padrão de qualidade para a flor de girassol, por Grieve & Poss (2010).…”