Dormancy breaking of ‘Kampai’ peach trees with alternative products in subtropical regions

Peach trees initiate flowering and then dense budding when the temperatures in winter are steadily low. When temperatures during the winter are high or when the chilling accumulation needs of the cultivar are not met, it is necessary to apply chemicals that stimulate flowering and budding in a uniform manner. This study aimed to evaluate alternative products for breaking the dormancy of ‘Kampai’ peach trees in a subtropical region. The experiment was conducted with ‘Kampai’ peach trees in the 2018, 2019 and 2020 production with the following treatments: (1) negative control composed only of water (control); (2) positive control composed of hydrogen cyanamide at a dose of 1.5% (commercial product Dormex®) plus 4.5% mineral oil; (3) Erger G® organomineral fertilizer supplemented with calcium nitrate at a dose of 3%; (4) potassium nitrate at a dose of 5%; and (5) copper sulphate at a dose of 0.3%. We evaluated affected budding capacity, flowering, the production cycle, peach production, the quality of peach trees and the enzymatic activities of catalase and guaiacol peroxidase. Hydrogen cyanamide and the organomineral fertilizer Erger G® promoted earlier flowering and an earlier production cycle. On the other hand, hydrogen cyanamide and copper sulphate stimulated flower opening and peach production. The chemicals used decreased catalase activity (24 h after application) and increased guaiacol peroxidase activity (6 h after application). The application of copper sulphate may be an option to break the dormancy of peach trees in the subtropics.

Germinability and Seedling Growth Performance of Chilli (Capsicum annuum) Seeds in Response to Different Gibberellic Acid Concentrations Pre-Treatment

Chilli seeds are always associated with physiological dormancy characteristics or endogenous dormancy that has affected their germination potential. Problems noticed on the low seed germination rate, vigour growth, further may lead to the poor seedling growth pattern of chilli crop production. Gibberellic Acid (GA3) which is usually used as a treatment solution is not a new advent of seed dormancy breaking methods for chilli. But, looking forwards to a better GA3 concentration is still needed for the discovery of this treatment potential effect on chilli seed germinability and seedling growth. Thus, this study aimed to evaluate the effect of different GA3 concentrations on seed emergence and seedling growth performance in chilli. In this experiment, chilli seeds were imbibed with 25 mg/L, 75 mg/L and 125 mg/L concentration of GA3 with three replications each; for 24 hours at room temperature (32±4°C) and the untreated seeds as a control. The data collection on final germination percentage was taken daily for 21 days after sowing. While the 15 germinated seeds were directly planted on the 5 polybags arranged in the net house of Junaidy Jonik Farm, Sabah, Malaysia. The experiment was arranged in a completely randomized design with three replications. Data were subjected to analysis of variance with SAS version 9.4 and the significant means were separated by the least significant difference test at P<0.05. Significant differences were observed in the seed germinability measured; germination rate index (GRI), mean germination time (MGT) and final germination percentage (FGP), as well as on seedling vigour index (SVI) between treated and control seeds. Conversely, plant height, number of internodes, number of leaves and fresh weight of seedlings showed no significant differences among treatments. It was concluded that the use of GA3 was able to enhance chilli seeds germinability and could display a better SVI than the control. It is recommended to use GA3 treatment at 25 mg/L of concentration, as it may give an advantage to both economic and biological importance in producing higher germinability and seedling growth performance in chilli.

Gibberellic acid promotes dormancy-breaking of rice seeds and the formation of abnormal seedlings

O arroz é uma das espécies que apresenta dormência após a colheita, podendo esta ser prolongada durante o armazenamento das sementes. Este trabalho teve por objetivo determinar se o ácido giberélico (GA3) é um promotor eficiente da superação de dormência em sementes de arroz e avaliar mudanças nas estruturas biológicas via histoquímica. A cultivar utilizada foi a SCS122 Miura submetida a 0 mg L-1, 500 mg L-1 e 1000 mg L-1 de GA3. Foram realizadas análises de germinação, viabilidade, comprimento de raiz, parte aérea e plântula, microscopia óptica do amido e quantificação dos açúcares solúveis totais. A utilização de 500 mg L-1 e 1000 mg L-1 de GA3 foi eficiente para a superação da dormência de sementes de arroz, reduzindo o percentual de sementes dormentes para 4% e 1% respectivamente. Apesar de reduzir o percentual dormência, a presença de GA3 provoca aumento do percentual de plântulas anormais, e por isso, nas concentrações utilizadas, não pode ser recomendado como método de superação em sementes de arroz. A microscopia óptica é eficiente para verificar que com a superação de dormência, ocorre a degradação dos grânulos de amido, aumentando a disponibilidade de açúcares solúveis totais para o crescimento e desenvolvimento de plântulas.

Non-Deep Physiological Dormancy in Seed and Germination Requirements of Lysimachia coreana Nakai

This study aimed to determine the type of seed dormancy and to identify a suitable method of dormancy-breaking for an efficient seed viability test of Lysimachia coreana Nakai. To confirm the effect of gibberellic acid (GA3) on seed germination at different temperatures, germination tests were conducted at 5, 15, 20, 25, 20/10, and 25/15 °C (12/12 h, light/dark), using 1% agar with 100, 250, and 500 mg·L−1 GA3. Seeds were also stratified at 5 and 25/15 °C for 6 and 9 weeks, respectively, and then germinated at the same temperature. Seeds treated with GA3 demonstrated an increased germination rate (GR) at all temperatures except 5 °C. The highest GR was 82.0% at 25/15 °C and 250 mg·L−1 GA3 (4.8 times higher than the control (14.0%)). Additionally, GR increased after cold stratification, whereas seeds did not germinate after warm stratification at all temperatures. After cold stratification, the highest GR was 56.0% at 25/15 °C, which was lower than the GR observed after GA3 treatment. We hypothesized that L. coreana seeds have a non-deep physiological dormancy and concluded that 250 mg·L−1 GA3 treatment is more effective than cold stratification (9 weeks) for L. coreana seed-dormancy-breaking.

Seed germination response of Indian wild pear (Pyrus pashia) to gibberellic acid treatment and cold storage

Knowledge of seed germination behaviour of different seed sources of tree species is useful in selecting the most responsive and adaptive ones for propagation and germplasm conservation. The wild Himalayan pear (Pyrus pashia Buch-Ham ex D. Don) produces highly nutritious edible fruits that are consumed by local communities. The populations of the species are threatened due to exploitation and lack of adequate conservation programmes. The study was conducted to examine the germination response of P. pashia seeds from two sources (S1-Champawat and S2-Pithoragarh) in Uttarakhand state of India, to different GA3 treatment and also to assess the viability and longevity of the seeds in cold storage (5 °C) for three years. In both sources germination percent (GP) increased significantly under GA3 treatment and speed of germination was also enhanced (reduction in mean germination time). In Source, 1 GP increased under all GA3 application, highest being 94% under GA3 500 ppm treatment. In Source 2, GP of seeds doubled under 100 ppm GA3 treatment while its higher concentrations did not improve the germination. However, the differences observed in germination between the seed sources could be due to differences in the dormancy levels and/or sensitivity to dormancy breaking elements across their geographical range. Thus, exogenous application of GA3 is suggested for enhancing the germination in seeds of P. pashia. Seeds responded to cold storage by increased germination with duration, i.e. highest after three years in storage, indicating that the seeds got the required chilling treatment for overcoming dormancy.

Improving germination with pre-sowing technique on Caliandra calothyrsus Meissn

Red Calliandra (Caliandra colothyrus) is a high-quality energy wood raw material that can be produced rapidly. It’s ideal for making wood pellets. The need for wood pellets is on the increase globally. For the production of wood pellets continuity, sufficient materials were required, requiring the development of red calliandra cultivation. The long duration of the seed germination process due to the hard seed coat is an obstacle in the generative propagation of red calliandra. This study aimed to determine the best treatment for red calliandra dormancy breaking and simultaneous germination. A factorial fully randomized design (F-CRD) with two treatment factors was used in this study. The first factor is type of solution (P) with three levels consisting of: P1: soaking in water; P2 : immersion with MSG solution (12 grams/liter); P3 : immersion in young coconut water (100%). The second factor is the length of immersion time (T) with three levels consisting of: T1: soaking time for 8 hours; T2 : immersion time for 12 hours; T3 : immersion time for 16 hours. Each treatment consisted of 20 seeds, which were replicated three times for a total of 540 seeds. The initial day of germination, length of germination, percentage of germination, and germination rate index were all measured. The results showed that that the most optimal germination for red Calliandra found in the P1T1 treatment (soaking in water for 8 hours). It can be shown from all observed parameters

Studies on Seed Dormancy Breaking in Cucumber (Cucumis sativus L.) Variety Poinsett

Experiments were carried out to study the effect of chemicals in breaking the dormancy of cucumber. The study was conducted at the Department of Vegetable Science, Horticultural College and Research Institute, Coimbatore during 2017-2018. The seeds of cucumber variety Poinsett were treated with various chemicals immediately after harvest to standardize the best dormancy breaking treatment. The design of the experiment was Factorial Randomised Block Design with two replications. The seeds were treated with the chemicals for 12 hrs and 24 hours duration. The germination test was conducted. Observations on seed and seedling quality parameters viz., speed of germination, and germination percent, vigor index I and vigor index II were recorded. At 12 hours duration, the highest speed of germination (23.29) was recorded in T2 (GA3150 ppm) whereas the highest germination percentage (92) was recorded in T8 (Ethrel150 ppm). At 24 hours duration, the highest speed of germination (30.77) and the highest germination percentage (86) was observed in T12 (KNO3500 ppm). At 12 hours duration, the highest Vigor Index I (2800.16) was recorded in T9 (Ethrel 500 ppm) while the vigor Index II was the highest (12.19) in T8 (Ethrel150 ppm). At 24 hours duration, the highest Vigor Index I (2349.28) was observed in T10 (Ethrel 1000 ppm) while the vigor Index II was the highest (14.066) in T11 (KNO3150 ppm).

Sanity and Germination of Treated with Clove Extract Jurema-Preta and Faveleira Seeds

The Mimosa tenuiflora (jurema-preta) and Cnidoscolus quercifolius (faveleira) are quite common species in the Caatinga biome, being used from forage production to energy generation and in the recovery of degraded areas for reforestation purposes, among other uses. Considering the need and importance of studies related to forest seeds health, especially native seeds and taking into account the scarcity of studies in the literature regarding the association of pathogens to the seeds of the species studied, this work aimed to evaluate the efficiency of the hydroalcoholic extract of clove on germination and incidence of fungi associated with seeds of jurema-preta and faveleira. The experiment was conducted in the Laboratory of Forest Pathology, Center of Health and Rural Technology, Federal University of Campina Grande, Patos, Paraíba, Brasil. For the germination test we performed the dormancy breaking of seeds that were then treated with clove plant extract, and as substrate, washed and sterilized sand was used. Germination percentage and Twinning speed index (SVI) were evaluated. The sanity test was performed using the filter paper method "Blotter Test" for the development of microorganisms. The treatments consisted of: 0%, 25%, 50%, 75% and 100% of clove extract, with 4 repetitions of 25 seeds. The design used was entirely randomized and the means were compared using Tukey's test at 5% probability. The clove extract, in higher concentrations, provided an increase in germination and SVI of the species. It was identified in the seeds of jurema-preta, the fungi Aspergillus niger, Aspergillus flavus, Aspergillus glaucous, Rhizopus sp, the genus Phoma sp. In the seeds of C. quercifolius the microflorea was composed by fungi Aspergillus niger, Aspergillus flavus, Aspergillus glaucous, Rhizopus sp, Aspergillus alutaceous and Aspergillus candidus.

Dormancy Breaking Treatments in Northern Wild Rice (Zizania palustris L.) Seed Suggest a Physiological Source of Dormancy

Dormancy is a limiting factor for breeding in northern wild rice (NWR; Zizania palustris L). This study developed a dormancy curve and tested a combination of scarification and hormone treatments, across three timepoints, for their ability to break dormancy in NWR and produce viable seedlings and plants. A dormancy curve was established across 9 months post-harvest, which showed maximum germination (95%) by 17 weeks post-harvest and high germination (≥81 %) through the rest of the testing period. Next, dormancy breaking treatments were tested. At 1 week post-harvest, few seeds germinated (≤ 15 %) across all treatment combinations. However, sulfuric acid increased germination shortly after harvest (5.8 %), compared to water (0.5 %) and NaClO (0 %) but resulted in stunted seedlings, all but one of which died shortly thereafter. At 7 weeks, sulfuric acid treated seeds did not result in significantly higher germination than water and maximum germination was still below 15%. By 11 weeks post-harvest, the water treatments had the highest germination and resulted in the most viable plants, indicating that dormancy had begun to break naturally and exceeded the effect of the other scarification treatments. Hormonal treatments had no significant effect on germination or seed viability and no strong conclusions could be drawn about their effect on seedling or plant health. Due to the inability of early germinated seed to consistently produce viable plants and the increase in germination following sufficient cold storage, it is likely that NWR seed has intermediate or deep physiological dormancy.