This study evaluated the differences in growth performance of the transplanted sago palm suckers with different earliness of trunk formation. Six- and nine-month-old suckers after transplanting (hereby abbreviated as the 6-MSAT and the 9-MSAT, respectively) were selected and started to measure the growth parameters. At about 57-60 months after transplanting (MAT), some of the 9-MSAT have attained to initiation of trunk formation and trunk formation stages. The others were still at the rosette stage as well as the 6-MSAT. During the first year establishment, the elongation rate of the 6-MSAT was slower than that of the 9-MSAT, but they were gradually similar thereafter. Suckers that attained to the trunk formation stage earlier showed the fastest elongation rate followed by those at the initiation of trunk formation and the rosette stage. However, their leaf emergence rates were similar. Suckers at the trunk formation stage were the tallest and produced the highest numbers of leaves followed by those at the initiation of trunk formation and rosette stages. In most cases, suckers at the rosette stage were characterized with a lower plant height at about less than 6 m. As the plant height was over 6 m, the growth stage progressed. The initiation or trunk formation stages could be indicated by the appearance of the leaflet length of the youngest expanded leaf, which should be about 130-140 cm long.
Sufficient application of nitrogen (N) is necessary to increase passion fruit production, although excess N is believed to be toxic. However, the impact of toxicity by excess use of N fertilizer is unknown. Three different solutions containing 100 mM NH4-N, 100 mM NO3-N, or intermixed 50 mM NH4-N and 50 mM NO3-N (Mix-N) were applied for 4 weeks to passion fruit grown in sand to understand the toxicity of excess N. Visible damage, vegetative growth, and leaf mineral contents were examined. Severe necrosis and defoliation were observed in the NH4-N plants because of high accumulation of leaf NH4-N. The necrotic leaves contained 1.2-2.5 mg·g-1 dry wt NH4-N, whereas healthy leaves contained only 0.1-0.4 mg·g-1 dry wt. Passion fruit recovered quickly from this toxicity. Two weeks after fertilizer application was stopped, newly emerged leaves showed no symptom of necrosis or irregular accumulation of NH4-N. Chlorosis and defoliation observed in the NO3-N plants were attributed to a nutrient unbalance. No visible symptom appeared in the Mix-N plants even under equally high N concentrations of 100 mM.
Morphogenesis of reproductive organ was correlated with external appearance of flower buds in cherimoya, and then pollen-tube growth in pistils incubated after pollination was observed chronologically to explain low pistil receptivity in early spring and mid summer. In April, when minimum temperatures were approximately 10°C, pollen-tube growth was suppressed and many impaired ovules were observed, suggesting a shortage of photosynthate accumulation in flowers. After May, when the minimum temperature increased to more than 15°C, faster pollen-tube growth and less impaired ovules were observed, although a large deviation in pistil receptivity was observed until mid May. This deviation might have been a result of nutrient competition between pistils in a multiple-flower. In late May to late June, when temperatures were 15-30°C, pistil receptivity was highest throughout the season with small deviation. After late June, when night temperatures often exceeded 25°C, pistil receptivity decreased, and many impaired ovules were observed in July. Increased respiration and thereby exhaustion of floral organs might be caused by high night temperatures. Besides the effects of low pollen viability, the low fruit set in early and late season was considered to be attributed to the impaired pistil development.
This paper addresses farm household common bean seed access behavior and seed quality issues in light of farm household socioeconomic characteristics. The notion that seed from informal source is poor quality and informal seed market (ISM) is the last resort for the poor household is closely examined. Data for this study were gathered in 2011 using structured questionnaire interview of randomly selected farm households. Seed samples were collected from the interviewed farmers, ISM and formal sources. On average, 93% of the farmers obtained seed from the informal sources while the remaining was accessed from the formal source. One-third of farm households consistently acquired seeds from ISM regardless of whether it is in normal or stress year. Higher proportion of women headed and the poor households tend to procure seed from informal sources (mainly ISM). However, the proportion of the well off farmers accessed seed from ISM was also significantly high (about 1/3) contrary to the commonly held belief that the well off farmers are seed self-sufficient and procuring seed from ISM is a sign of vulnerability. The informal seed source is more responsive and accessible to men and women headed households of all categories during the stress and normal years. Such an important entity of the informal seed source, ISM, deserves consideration as a positive force in the dissemination of new variety or seed hand in hand with strengthening farmer seed production. The formal seed sector has also a crucial role in new germplasm or quality seed introduction, recognition, and strengthening of the informal seed sector. Physical and germination quality of the seeds obtained from informal sources had met the standard despite minor defects. Even though seed from the informal seed sources is flexible, offers acceptable quality seed and serves all categories of farm households, it has mixtures and insect pest infestation. Hence, improvement of seed storage, insect control, and basic information about varietal characteristics including variety names has to be addressed for enhanced quality seed distribution.