Cluster-Zone Leaf Removal and GA3 Application at Early Flowering Reduce Bunch Compactness and Yield per Vine in Vitis vinifera cv. Pinot Gris

Compact bunches have been often associated with higher susceptibility to Botrytis cinerea and therefore reduction in berry quality in grapevine. The objective of this study was to evaluate three management methods (early leaf removal, gibberellic acid, and their combination) for reducing bunch compactness in Vitis vinifera cv. Pinot gris trained in two different training systems with contrasting vigor (Guyot and pergola). Treatments were applied at BBCH 62 or BBCH 65 and yield components, total soluble solids, fruit set, and bunch compactness parameters were evaluated. Both treatments individually reduced berry number, mean bunches weight and bunches compactness as well as yield per vine when compared to control-untreated vines. However, no major differences were observed when both the treatments were applied in combination for Guyot or pergola although a higher reduction in yield was detected for Guyot and a significant increase in total soluble solids was observed in pergola. Our study suggests that intense leaf removal and gibberellic acid applied at early flowering can help reducing bunch compactness in Pinot gris and showing it in two training systems. In particular, leaf removal represents a valuable alternative to plant growth regulators (i.e., gibberellic acid) as applicable in organic viticulture.

The Imbibition, Viability, and Germination of Caper Seeds (Capparisspinosa L.) in the First Year of Storage

The caper is a shrub that adapts to harsh environments when it is established, but it presents serious difficulties in its propagation, both by cuttings and by seeds. Its seeds have low germination percentages, and germination is a very slow process. Significant increases in germination have been obtained with scarification and with the addition of gibberellic acid (GA3) to the substrate, leading to the hypothesis that they have possible physical and physiological dormancy. However, the only way to examine the water-impermeability of the cover is through imbibition analysis. This study analyzes the imbibition, viability, and germination of two seed lots, obtained in different years and evaluated immediately after their collection (FS) and after being stored (7 °C) for one month (DS) and one year (SS). The seed moisture content stabilizes from the fourth day, exceeding in all cases 31% in all three seed states tested (FS, DS and SS). This allows the germination of all viable seeds, only with the addition of GA3 to the germination substrate, without the need for scarification, so that caper seeds exclusively appear to present a physiological latency. Germination decreased in storage, even with just one month. With the GA3 addition, high germination values were obtained (up to 95% in FS).

The Effect of Gibberellic Acid on the Production Characteristics and Biochemical Parameters of Tetraselmis Suecica in an Enrichment Culture

The use of gibberellic acid as a stimulator of microalgae growth has beensubstantiatedexperimentally.This research aimed to assess the effect of exposure to a wide range of gibberellic acid concentrations on the growth dynamics ofthe microalgaTetraselmissuecicain an enrichment culture. The duration of the experiments was 14 days. It has been shown that gibberellic acid,atconcentrations of 0.39–3.20× 10−8M, stimulates algaegrowth. In this research, the exposure to gibberellic acid at concentrations of 0.39–3.20 × 10−8M was accompanied by a variation in the pattern of growth curves: the maximum number of cells was recorded on day seven of the experiment. A higher concentration of the phytohormone (3.84 × 10−8М) inhibited the increase inculture density. The growth of theT. suecicaculture in the control group was 332%;the growth of the culture exposed to gibberellic acid at a concentration of 0.39 × 10−8M was1136%. The values of the specific growth rate ofT. suecicawere estimated for different periods of cultivation. On day14 of the experiment, the biochemical composition of microalgae biomass was analyzed.According to the results, gibberellic acid stimulated the accumulation of carbohydrates, proteins, and chlorophyll. Nevertheless, the phytohormone had no effect on lipidaccumulation. An assumption was made thatexposure to low concentrations of phytohormone stimulates the growth of microalgae by reducing the lag phase of growth. Keywords: gibberellic acid, microalga, cultivation, lipids, carbohydrates, proteins

Seeds of the threatened dry rainforest tree Cadellia pentastylis (Surianaceae) are non-dormant

Cadellia pentastylis (Surianaceae) is an Australian endemic threatened rainforest tree. Irregular flowering and fruiting events coupled with high rates of infertility and insect predation has meant that seed testing has not been possible for this species. Seeds were opportunistically collected from a wild population in early 2021, which allowed for the first germination tests to be conducted. In this study, the presence of physical dormancy was examined by performing an imbibition test using scarified and non-scarified seeds. We also investigated whether a 5-min heat shock treatment at temperatures ranging from 60 to 120°C improved germination success. The presence of physiological dormancy was also examined by recording germination success following a gibberellic acid or smoke-water pre-treatment. Both scarified and non-scarified seeds readily imbibed water over a 72-h period, and several seeds had germinated in both treatments after 48 h. Final germination proportion and t50 following a heat shock, gibberellic acid or smoke-water pre-treatment did not significantly differ from the controls. We conclude that C. pentastylis seeds are non-dormant. Although a palisade cell layer has been reported in the endocarp, our results suggest that this layer may not be sufficiently formed to restrict germination. We recommend that seeds are collected from populations following dispersal and propagated shortly after or stored as conservation collections in ex situ Seedbanks.

Osmoprotection in Salvia hispanica L. seeds under water stress attenuators

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.

In vitro propagation from nodal segments of Lippia origanoides (chemotype A)

ABSTRACT: This research described an efficient micropropagation protocol for Lippia origanoides (Verbenaceae). Sterile seeds were used to obtain germinated seedlings in Murashige and Skoog medium (MS) supplemented with sucrose and agar. The nodal segments obtained from seedlings were grown on MS medium supplemented with different concentrations of gibberellic acid (GA), benzylaminopurine (BAP) and 1-naphthalenacetic acid (NAA) with BAP. The callus induction, shoots length, shoots number and root length, were analyzed. The treatments showed high percentage of callus formation at 0.5 to 1.5 mg L-1 of BAP alone or in combination with NAA (0.1 mg L-1). The highest value of shoot number per nodal segments was obtained at 1.5 mg L-1 of BAP (4.3 ± 0.8). The obtained plantlets were better rooted in vitro in the absence of plant growth regulators (PGRs) and they showed acclimatization rate of 90%. We reported a protocol for in vitro propagation and acclimatization of L. origanoides for A chemotypes from Colombia.