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Dynamics of Dry-Down in Seed, Head and Stalk from Sunflower Genotypes Sprayed with Chemical Desiccants After Physiological Maturity
2019
Cyntia Lorena Szemruch | Federico García | Sebastian Zuil | Christian Teysseire | Juan P Renzi | Miguel A Cantamutto | Santiago Renteria | Deborah P Rondanini
Chemical desiccation can advance the sunflower harvest time. Paraquat has been extensively used, but other less risky chemicals, as Carfentrazone and Saflufenacil, can rise as an alternative. Moisture levels of seed, head and the upper portion of stalk are all relevant for mechanical harvesting, but dry-down dynamics of each tissue is unknown. The aim was to study the dry-down dynamics of seed, head and stalk in sunflower genotypes sprayed with Paraquat, Carfentrazone and Saflufenacil after physiological maturity. Seven experiments were carried out in the field in Argentina (from 29 to 39º S) during 2014/2015 and 2015/2016. The genotypes used included hybrids and female inbred lines of both oil and confectionery types. The dry-down of sunflower plant was accelerated by desiccants with Paraquat, reducing seed and stalk moisture to a greater extent. The head moisture remained very high (>80 and 70%) during several days after application, without differences among desiccants and control. Dynamics of seed, head, and stalk moisture was not associated to vapor pressure deficit or meteorological conditions after chemical application. Loss of green color of leaves was not a reliable indicator of seed dry-down dynamics. Seed germination was not affected by chemical desiccation on either oil-type or confectionery female plants. Under broad conditions of these experiments, the Paraquat was effective for seeds/grains and stalks drying in both sunflowers hybrids and inbred lines. The slowly drying of heads makes it necessary to continue investigating with new doses and combinations of desiccants to ensure an optimal harvest. Desiccants were safe for seed germination, which benefits their usefulness in the seed industry.
Afficher plus [+] Moins [-]Effects Of Drought Stress on Germination in Fourteen Provenances of Pinus Brutia Ten. Seeds in Turkey
2015
Hakan Şevik | Nihat Ertürk
Pinus brutia Ten., Red pine, known to be tough drought resistant pine specie, could effectively be used for afforestation of disturbed areas. It is of great interest for the afforestation in arid zones. Appropriate seed sources for the specific areas guarantees reforestation success. Away from its native areas Pinus brutia Ten. is planted for its ornamental value and timber production purposes. Selection of drought resistant provenances can very well increase the survival success. In this study, the effects of water potential on germination were studied in fourteen provenances of Pinus brutia Ten. from Turkey. Water potentials between 0 and -8 bars were obtained using polyethylene glycol 6000 (PEG-6000) solutions. Seeds were kept for 35 day at 20 ± 0.5°C. A decrease in water potential produced a marked reduction in germination percentage and germination value. As a result, significant variations between the provenances were found. It was determined that, under a -8 bar water stress, Isparta-Bucak and Mersin-Silifke, respectively corresponding to 58% and 57% of the control group, were the least water stress affected provenances.
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