Sago palm seedlings were grown in a culture solution with individual exclusion of macro- (N, P, K, Ca, Mg) and micronutrients (Fe, B, Cu) during their early growth stages. In addition, control, tap water (no nutrient supply) treatment and treatments with half (N½) and twice (N2) the N concentration of that of the control were used. The N2 treatment accelerated the increase of plant length and leaf production from 42 and 70 days after the start of the treatments, respectively. The differences in the total plant length and number of leaves, shoot base diameter and dry weight, and total N uptake were significant between the N2 and N½ treatments. The -N treatment and tap water treatment showed a similar effect on the growth, namely inhibition of the increase of plant length and of leaf emergence as well as of all the growth characters examined. The -N treatment also reduced significantly the SPAD value and root dry weight. The -P treatment reduced significantly the plant length, leaf area, shoot base diameter, total plant dry weight and the uptake of each nutrient, although the total N concentration in the petioles and roots was significantly higher than in the control. No significant effects on the growth characters and nutrient uptake were observed in the -B and -Cu treatments, except for the total plant length in the -Cu treatment and total B uptake in the -B treatment. Due to a probable enrichment of K, Ca, Mg, and Fe by the vermiculite used as medium, the growth and nutrient uptake of the seedlings grown under the -K, -Ca, -Mg, and -Fe treatments were similar to these of the control. In conclusion, the growth responses of sago palm seedlings to the deficiencies of N and P were remarkable, compared to those to the other nutrient deficiencies. In future, more precise studies for the -K, -Ca, -Mg, and -Fe treatments should be carried out.

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Sago palm seedlings were exposed to 2 cycles of diurnal change of NaCl concentration in the culture solution in a hydroponic system for 4 months. During the experiment, the emergence rate of new leaves in the treated plants tended to be slow, compared to that of the control plants. However the number of dead leaves was the same in both control and treated plants. The total N and P concentrations in the leaflets and petioles and the leaf area at each leaf position did not change with the treatment. The increase of the SPAD value was slow in the treated plants. The photosynthetic rate, transpiration rate and stomatal conductance in the treated plants decreased by about 40%. The Na⁺ concentration increased in all the plant parts with the treatment, especially in the roots and petioles at the lower leaf positions. The K⁺ concentration decreased in the roots and petioles, whereas it increased in some leaflets. Although a large difference in the decrease in Mg²⁺ concentration was found in the cortex, the difference was negligible in the stele of adventitious roots, petioles and leaflets. Based on these results, it is considered that sago palm plants growing in a brackish water area are able to maintain a low Na⁺ concentration in the leaflets of active leaves by storing Na⁺ mainly in the roots and petioles. The factor limiting the photosynthetic rate under NaCl stress was the reduction in stomatal conductance that resulted from a trade-off with the decrease in the transpiration rate for maintaining the water status in the leaves. Although chlorophyll production was depressed, the absorption of macronutrients was not inhibited by salt stress and there was no lack of materials such as N and Mg for chlorophyll production. Therefore, it was found that the chlorophyll concentration could increase up to high levels over a comparatively long time. These factors may account for the resistance of sago palm to salt stress and ability to grow even with a reduction of the growth rate.

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The present study evaluated the survival rate and the growth performance of sago palm suckers during the early establishment in response to storage conditions (shaded and unshaded conditions) prior to the nursery period. Moreover, changes in the contents of macronutrients (N, P, K, Ca, and Mg) as well as nonstructural carbohydrates in the pith were also elucidated. Storage periods of 0, 3, 7, 15, and 25 days were used. Storage of the collected suckers prior to the nursery period reduced their freshness due to the reduction of the moisture content. The suckers stored under shaded conditions lost less weight than those stored under unshaded conditions, especially during the 3- to 15- day period after storage (DAS) and at 25 DAS, they showed a similar weight loss. While the pith dry matter percentage and the contents of macronutrients as well as total sugar in the pith increased with the prolongation of the storage period, the content of starch decreased steadily. The changes in those parameters between the two storage methods in each storage period were not significantly different in most cases. The contents of macronutrients, in general, were maximum mainly at 7 and 15 DAS. They decreased thereafter when the period was extended to 15 or 25 days. Direct nursery transfer resulted in a survival rate of 87.5 % and the rate decreased with the prolongation of the storage period, regardless of the storage methods. A long storage period (25 days) considerably reduced the sucker survival rate below 20 %, even when the suckers were kept under shaded conditions and none of them was able to survive when they were stored under unshaded conditions. The survival rate of sago palm suckers during the nursery period could be enhanced by using freshly prepared suckers. If the suckers need to be stored for any reasons, placement under shaded conditions for less than a one week is recommended.

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Neglected by research and development, knowledge of the genetic diversity in Ethiopian yams is found mainly with the local farmers. The local yam classification system in Southern Ethiopia was studied through individual and key informant interviews. Data collected include attributes/traits of each landrace used in the folk taxonomy. Local farmers recognize two major categories of yams: ‘hatuma boye’ (‘male’ yam) and ‘macha boye’ (‘female’ yam). This categorization has no reference to the reproductive biology of the plant. “Female” yams mature early and produce tubers of excellent quality, but are less vigorous in growth compared to ‘male’ yams and yield poorly under sub-optimal conditions. Whereas, ‘male’ yams mature late, grow vigorously and are tolerant to drought. Individual landraces are further identified based on variations in maturity time, morphological and/or growth attributes. Eighty-two yam accessions collected from Gedeo, Sidama, Wolayita and Gamo-Gofa zones were characterized using 42 qualitative morphological variables. Cluster and principal component analyses gave seven distinct groups, revealing that the overall structure of morphological diversity is consistent with farmers’ classification. Nevertheless, no clear morphological variations were observed between some differently named landraces. Few landraces known by the same vernacular name were also morphologically distinct. This study demonstrated the existence of a well-defined local classification system and a wide variability among the accessions studied. It also revealed the need for detailed phylogenetic studies to determine the species identity of the accessions studied and broaden the knowledge base of Ethiopian yams.

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To improve the efficiency of intergeneric hybridization between sugarcane and Erianthus arundinaceus, we examined their responses to day-length and harvesting time on Ishigaki Island, Japan, in 2008 and 2009. To suppress floral initiation, the day-length was extended to 14 h by providing light to three E. arundinaceus clones, JW4, JW630, and IJ76-349 before sunrise. Then, to induce flowering, the day-length was reduced by 20 min/week until a day-length of 11.5 h was attained. The day-length treatment effectively delayed flowering in the JW4 and JW630 clones, whereas the light-treated IJ76-349 did not flower at all. Delays of 12 to 22 days and 14 to 25 days were confirmed in the JW4 and JW630 clones, respectively. Regarding the effects of harvesting time, April-harvested JW630 showed a 5-day delay compared to the February-harvested plants, while there was no significant difference in JW4. However, when we combined late harvesting and day-length treatment, significant delays of 15 days in JW4 and 33 days in JW630 were confirmed. Since the pollen of JW4 and JW630 successfully germinated after the day-length treatment, these treatments are considered to be useful for overlapping the flowering dates of sugarcane and Erianthus on Ishigaki Island.

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