In the rainfed regions of West Africa, rice production is greatly influenced by rainfall quantity and frequency, especially the upland ecologies. Establishing alternative methods to improve soil water retention can be the key to stable yield increases. Experiments were conducted twice on 7–9 fields to evaluate furrow sowing and its effects on seedling emergence under rainfed conditions in central Benin in 2015. Narrow (3 cm wide) and wide (10 cm wide) furrows were compared against conventionally tilled plots under dry and wet conditions. Under the former conditions, the soil moisture in the furrow was 2.5% higher and the emergence rate was 16–25% higher than in control. Emergence was the earliest in the narrow furrow. Under wet conditions, the soil moisture in the furrow was 5% higher than in control, while the emergence rate was the highest in the wide furrow, followed by control and the narrow furrow. Emergence was earlier in the wide furrow and control than in the narrow furrow. Furrow sowing was effective in increasing soil moisture and emergence. However, when the soil moisture was higher than around 10%, the narrow furrow had a negative effect on emergence while the wide furrow continued to have a positive one. These results suggest that while the narrow furrow was effective in very dry soils, the wide furrow had greater adaptability to soil moisture variations and retained soil moisture for better plant establishment under rainfed conditions.

To clarify the effects of floral disbudding on mango flowering and fruit set, floral buds in each panicle were partly removed one week before flowering started into three treatments, i.e., leaving the basal, middle or apical portion of the panicle. Flowering and fruit set were subsequently recorded. A similar flowering order was observed in disbudded panicles and those without disbudding as a control; the number of hermaphrodites increased rapidly during the early–mid period of flowering, and the number of staminate florets also increased rapidly during the mid–late period. The number of hermaphrodites tended to be larger in the middle portion of the panicle. The percentage of hermaphrodites markedly increased by floral disbudding, it was higher than 40% when the basal or middle portion of panicle remained, while it was low approximately 30% in the control panicles. The percentage of hermaphrodites was higher in the panicle containing a smaller number of total florets. The number of fruit set tended to increase in each panicle portion by floral disbudding. The number of fruits containing normal seeds per panicle was largest when the middle portion of panicle remained, while the smallest in the basal portion of the control panicles. The percentage of fruits containing normal seed was highest (50%) when the middle portion of the panicle remained, while the percentage was lower (25%) in the control panicles. In mango, floral disbudding was found to be feasible for reducing a risk of male-dominated flowering and nubbin-fruit setting.

Rhizomes from Curcuma species are widely used as spices, dyes, and medicines. As medicinal constituents in Curcuma species, curcumin and essential oil components (terpenoids) are produced during plant growth. We examined the changes in percentages and constituents of essential oils in the organs of the Curcuma species turmeric and yellow zedoary cultivated in Kochi, Japan during different growth periods. Turmeric had higher aboveground and rhizome dry weights and a lower harvest index than yellow zedoary. In both species, essential oil percentages were significantly greater in rhizomes than in leaves and stems. During the growth period of October to November, essential oil percentages significantly increased in rhizomes and decreased in leaves. Essential oil amounts, calculated as the products of percentage content and dry matter, were greatest at maturity in November as rhizome dry weight and essential oil percentages increased. A chromatographic analysis revealed that turmeric had 22 essential oil constituents comprising more than 1% of the relative area and that ar-turmerone and zingiberene were the major constituents. The ar-turmerone content in rhizomes tended to increase with growth. Yellow zedoary had 21 essential oil constituents, and the major constituent was 1,8-cineole. Essential oil constituents in yellow zedoary were similar between leaves and rhizomes, but were different from those observed in stems. 1,8-Cineole tended to decrease in rhizomes with growth. Thus, the essential oil percentages and constituents were different between species, but these traits also varied in different organs during growth.

Global warming has detrimental effects and causes crop damage. However, high temperatures can be mitigated to a great extent by maintaining the root-zone temperature within a normal range. In a previous paper, a novel strategy, involving a soil-cooling system, was found to achieve this goal by cooling the soil under environmental conditions. Thus, the present study is intended to determine the effect of soil cooling on growth performance and soil chemical properties, focusing on temperate root crops under a tropical climate. Radish was grown in triplicate without the addition of fertilizers and was evaluated for its growth performance in terms of weight (taproot and leaves), length (taproot and leaves), root tail length, and numbers and the area of leaves. The findings showed that radish plants grown in cooled soil presented significant differences in terms of their average weight (taproot and leaves), average length (taproot), leaf area, and length of root tail (p < 0.05). The cooled and uncooled soils showed differences in the contents of macro- and micro-nutrients during their growth. Therefore, the present study demonstrates that the modulation of soil temperature allowed the cultivation of a temperate root crop, and this strategy will be applicable not only in tropical countries but also in temperate ones influenced by climate change in the future.

We investigated the growth characteristics and starch productivity of gebang palms grown in Kupang, East Nusa Tenggara and on Muna Island, Southeast Sulawesi, Indonesia. In surveyed sites, the palms grew naturally or were planted around the houses. In Kupang, all parts were used for multiple purposes, and starch extraction was also performed. According to the results of an interview with a veteran farmer of gebang palm in Kupang, the optimum harvest time for starch production is around the flower bud formation stage before flowering, which takes 25 to 30 years from seedlings. The plants at the survey sites ranged from 13–20 m in trunk length, 50–60 cm in trunk diameter, and 3200–5100 kg in trunk weight at the flower bud formation stage. Additionally with high pith starch percentages (60–70%), 5 of 10 plants at the flower bud formation stage had contents of more than 1000 kg, and the maximum starch content (yield) was about 1400 kg. Since the growth of trunks and the starch contents in the pith differed depending on the surveyed site, it is necessary to examine the differences in the growth characteristics and starch productivities among the surveyed sites from the viewpoints of differences in the genetic backgrounds and the growth environments.

Hand pollination of salak is increasing in Thailand. To determine the favorable conditions for pollen collection, salak pollen was exposed to various temperature and humidity conditions. The germination percentage of fresh pollen exposed to humid conditions (90% relative humidity [RH]) varied little at temperatures ranging from 21 to 36°C for the initial 6 h following anthesis. Under dry conditions (10% RH), germinability quickly decreased, and the decrease was more remarkable at higher temperatures. To determine favorable storage conditions, pollen was stored under various temperature and humidity conditions. When pollen exhibiting 50% pre-storage germination was stored at room temperature (30°C), germination was suppressed within 7 days, regardless of humidity. When stored in a refrigerator at 5°C, the germination was ≈40% for 7 days at 63% RH. The germination remained the proper percentage of >20% after 14 to 60 days of storage at 36% RH. Germination was also >20% when stored in a freezer at −40°C for 360 days and thawed at 25°C with 60% RH. Germination decreased to <20% within 90 days of storage when stored at both −40°C or −20°C and then thawed under dry conditions (20–40% RH). Avoidance of hot and dry conditions was found to be necessary for the salak pollen. A temperature of 5°C at 60% RH was favorable for several days of storage, and 5°C at 35% RH was favorable for several weeks of storage. For several months to up to one year of storage, −40°C followed by thawing at 25°C at 60% RH is recommended.