To produce tetraploid plants effectively, we examined the effects of colchicine treatment on tetraploid induction from seeds of five polyembryonic genotypes in Citrus, Fortunella, and Poncirus. In the ‘Valencia’ sweet orange (C. sinensis), the germination rate decreased with increasing colchicine-treatment concentration and/or duration. The Meiwa kumquat (F. classifolia) and Hongkong kumquat (F. hindsii) showed high germination rates (>90%) in all treatments for 24–72 h, regardless of the colchicine concentration, although their germination rate decreased with any 96 h colchicine treatment. There was no regularity in the germination rates of the trifoliate orange variation ‘Flying-dragon’ trifoliate orange (P. trifoliata) or the ‘Swingle’ citrumelo [grapefruit (C. paradis) x trifoliate orange]. The effects of the treatment concentration and duration on the germination rate and the number of total seedlings differed among genera. Although the seedlings obtained after colchicine-treatment showed various ploidy levels such as tetraploids, octaploids, and chimeras (2x + 4x, 4x + 8x), the tetraploid induction rate varied greatly with the plant materials. The tetraploid induction rate per seed in ‘Valencia’ was highest (53.3%) with the 24 h treatment with 0.1% colchicine. The tetraploid induction rates in the Meiwa (50.0%) and Hongkong (30.0%) kumquats were greatest with 72 h treatment with 0.2%. The ‘Flying-dragon’ trifoliate orange and ‘Swingle’ showed the highest tetraploid induction rates with treatment of 0.1% for 24 h (10.0%) and 0.2% for 24 h (7.3%), respectively. Compared to Citrus and Fortunella, the tetraploid induction rate in Poncirus and its hybrid was low, and no regularity was observed among all of the conditions.

We explained the phytohormone profiles associated with the various stages of the parts of melon reproductive organ growth. This study was achieved using melon flowers that were obtained 0 to 7 days before flowering (DBF), after which their parts were divided into the sepals, petals, stamen and pistil. Then, we quantified simultaneously indole-3-acetic acid (IAA), abscisic acid (ABA), trans-zeatin (tZ), isopentenyladenine (iP), jasmonic acid (JA), methyl jasmonate (MeJA), gibberellin₁ (GA₁) and gibberellin₄ (GA₄). The IAA concentration increased rapidly at 0 DBF in the stamen. Likewise, the tZ, iP, GA₁, GA₄ and MeJA in the stamen had the highest concentration among the four parts. In contrast, ABA, JA, and MeJA concentrations in the petal decreased from 0 to 7 DBF.

Taro beetle damage has recently been reported on Gau Island, Fiji, causing economic loss for the taro business. This significantly reduced farmers’ incomes and the cultural value of taro. Swamp taro cultivation is expected to be a solution to taro beetle damage. Even though studies investigating the mitigation of taro beetle damage in paddy fields are not common, taro beetles do not have the ability to go beyond a certain depth in muddy condition. This study investigated suitable wetlands for taro cultivation by using the topographic wetness index (TWI). The calculation also considered protection forest zones and accessibility as analyzed by RapidEye satellite images, normalized difference vegetation index (NDVI), and buffer function. Results showed that 26.03% of the island’s mass has potential for the development of paddy fields. Although the result was larger than predicted, there are differences between potential areas for each village. However, these areas were more than double size of the existing farmland of each village. Estimated yields corresponding to the potential areas were also presented in the study; these indicated that more than half of villages might be able to yield more than 0.50 t of taro production.