Causes of Low Viability and Techniques to Improve Germination of Sago (Metroxylon sagu Rottb.) Seeds

The cultivation of sago, a species of palm growing in the wild in Mindanao and known for its high starch yield, is constrained by its low propagation rate.  Seed propagation, though desirable, is difficult with sago because it tends to produce seedless or parthenocarpic fruits and its seeds have a low germination. To address this problem, we studied the cause of seedlessness and poor germination of sago fruits and explored hydro-priming as a way of mitigating poor germination. Confirming the result of previous studies, six fruit lots of sago, involving a total of 18,566 fruits collected from four towns and three provinces in Mindanao, Philippines, showed a consistently high incidence of seedlessness, with only 504 (2.7%) of the fruits bearing seeds. The biggest lot (7,630 fruits) was 100 per cent seedless. Among fruits with seeds, studies of the effects of hydro-priming (cycles of soaking and drying) and water replacement during soaking treatments show that only the hydro-priming treatment has a significant effect on germination and incidence of normal seedlings. The highest germination percentage of 36.7% was obtained from seeds subjected to two cycles of hydro-priming without water replacement after 125 days. The control (continuous soaking) had only 8.3% germination. Likewise, the highest percent of normal seedlings (31.7%) was obtained with two cycles of hydro-priming without water replacement. The control had only 1.67% normal seedlings. The present studies support the following conclusions: (a) parthenocarpic fruit development is common among the sago palms studied, and (b) seed germination and production of normal seedlings are enhanced by hydro-priming without water replacement. The first conclusion is a confirmation of similar reports in literature, while the second conclusion is unique for this study

The Flowering Habit of Nipa (Nypa fruticans Wurmb.) in Semi-wild Stands of the Davao Region, Philippines

Observations on the flowering characteristics of nipa (Nypa fruticans Wurmb.) were carried out on at least 70 randomly selected palms in various semi-wild stands found in the Davao Region, Philippines (i.e., Bago Aplaya, Ecoland, and Talomo) from April 2010 until February 2011. The developmental stages of inflorescence were identified, described in detail, and arbitrarily divided according to morphological changes exhibited by the inflorescence. These developmental stages are as follows: emergence (E) stage, stage 2 (S2), pre-anthesis (PA) stage, and the antheses stage, which is divided into the female receptivity (F) stage and the male anthesis (M) stage. Among the parameters measured for each stage include the length of the inflorescence from base to tip, the number and length of staminate rachillae, and the number of female flowers. For morphological characteristics comparison of this monoecious inflorescence, different stands in Carmen, Davao del Norte, were observed. The Carmen stands were significantly more fecund compared to the Davao City stands. The former had more female flower count (61 vs. 58 per pistillate head) and more staminate rachilla count (33 vs. 17 spikes) than the latter. The final inflorescence length in Carmen was significantly taller than in Davao City (117.5 cm vs. 84.3 cm), suggesting that the plants in the former had longer tapping potential for sap production. The results have implications toward the future program of nipa hybridization to produce better varieties

Impacts of Long-term Weed Management on the Diversity and Abundance of Grasses in Banana Plantation Slopes in Davao City, Philippines

Banana is one of the main export products in the Philippines. The growing demand for banana products generates a need for plantation expansion even in erosion-prone areas like slopes. Effective farming practices in slopes are therefore needed to conserve the soil and establish a sustainable production. One of these systems is weed management, which is a critical component of farming practice in sloping lands. A 3-year study was conducted to compare manual and chemical (paraquat and glyphosate) weed management on the abundance and diversity of grasses in a banana plantation. Counts, biomasses, seed bank, and diversity indices of grasses were compared in identical experiments in 15% and 25% slopes. From the seed banks, 7 grass species were observed: Cyperus brevifolius, Cynodon dactylon, Eleusine indica, Imperata cylindrica, Paspalum conjugatum, Digitaria ciliaris, and Digitaria longiflora. Generally, there was a decreasing trend in the seed bank counts in both manual and chemical plots of 15% and 25% slope. However, the differences between treatments were not significant. Chemical treatments reduced the general counts and biomass of monocot weeds, but this effect was generally not significant. Chemical treatments significantly reduced the counts of P. conjugatum in 15% slope and the biomass of E. indica in 25% slope in the field. C. dactylon was found to be the dominant species in the field because of its early establishment in the slopes, its spreading growth and its allelopathic properties, which suppressed other species. There was a significant increase in diversity in both treatments on two slopes, but chemical plots had a significantly higher diversity compared to the manual plots. Chemical weeding was also less expensive and less laborious than manual weeding

Long-term Effects of Weed Management on Earthworm Abundance in a Banana Plantation in Davao City, Southern Mindanao, Philippines

Earthworm densities have been regarded as reliable indicators of soil health. A long-term field experiment was conducted in two sites (15% and 25% slope) to compare the effects of manual and chemical weeding (using paraquat and glyphosate) and determine other factors that may affect earthworm populations in a banana plantation. Based on four years of field observation, no significant difference in earthworm count between manual and chemical plots (15% slope: F-ratio: 0.96, p = 0.43; 25% slope: F-ratio: 14.18, p = 0.06) were observed. The earthworm species composition was found to differ between the two sites. The 15% site tends to have a higher earthworm population compared to the 25%-slope site, likely because of the former’s higher soil organic matter content. Earthworm populations were on a declining trend in both treatments for both sites, but regression analyses show these trends to be insignificant. Rainfall, organic mulch, and weed cover were not significantly correlated with the earthworm counts. However, the declining pH in both sites could help explain the decline in earthworm populations. Pontocolex corethrurus showed significant avoidance response to normal glyphosate concentrations (8.055 × 10–3 mL per 350 g soil) (p = 0.03), but not to paraquat (1.5 × 10–3 g per 350 g soil) (p = 0.55). Experiments suggest that both weed management treatments do not pose a significant threat to earthworms under the conditions studied. The negative effect of declining pH needs further study

Yield and Response of First and Ratoon Crops of Eggplant (Solanum melongena) to the Eggplant Fruit and Shoot Borer (Leucinodes orbonalis) under an Integrated Pest Management System

Eggplant (Solanum melongena) is a highly valued crop with an average production of 10 t·ha–1 and contributes to nearly PhP2 billion in the Philippine economy using conventional farming methods. An integrated pest management system was designed to control the eggplant fruit and shoot borer (EFSB) for increased productivity with reduction on harmful pesticide inputs. Under a split plot in randomized complete block design, two eggplant varieties, i.e., hybrid Banate King F1 (BK) and open-pollinated Dumaguete Long Purple (DLP), were tested under four different pesticide treatments, namely, (1) control–no pesticide, (2) organic–Bird’s chilli extract, (3) synthetic–spinosad + flubendiamide, and (4) combination–Bird’s chilli extract + spinosad + flubendiamide. After data was obtained, the first crops were ratooned and tested under the same IPM system. Data on yield and EFSB damage of the ratoon crops were compared with the first crop as influenced by eggplant variety and pesticide treatment. All plants were grown on plots covered with polyethylene mulch sheets under a uniform fertilization and fungicide regimen. Multiple cropping with regular field sanitation and inspection were also incorporated in the IPM system. Results indicate that BK is a superior variety over DLP with a gross yield of about 40 t·ha–1 and a marketable yield of about 20 t·ha–1 in 22 harvests. Ratoon crops produced lower yield than first crops with only 2 t·ha–1 in 12 harvests. Among the pesticide treatments, synthetic or combination treatments are superior over the control (no pesticide) or organic treatments. Use of open-pollinated DLP and chilli spray is inferior to hybrid and synthetic or combination sprays. Chilli spray also tends to nullify the effectiveness of synthetic pesticides when used in combination. The designed IPM system produced higher yield than conventional methods, but all treatments only provided moderate control over EFSB damage with average yield losses of about 50% in first crops and about 60% in ratoon crops

Notes on the Variation of Selected Morphological Variables in Semicultivated Stands of Sago Palms (Metroxylon sagu Rottb.) in Agusan del Sur, Southern Philippines

A survey covering 72 palms was conducted in the municipalities of Rosario, Talacogon, and Prosperidad, Agusan del Sur Province in Mindanao, Southern Philippines to study the variation in morphological traits of sago (Metroxylon sagu Rottb.). Among nine variables studied, two were classified as qualitative; the rest were quantitative. The qualitative variables were: the pattern of bands at the back of the rachis (banding pattern), and suckering pattern. Four banding patterns were observed, namely: striped brown and white band (SBWB), gray band (GB), strong brown band (SBrB), and strong black band (SBB). They occurred in equal proportion among the samples. The SBB seems to be associated with large trunk volume, while SBrB seems to be associated with low trunk volume. Suckering patterns were classified as: Type 1, when suckers arise from the rhizomes far from the mother plant and Type 2, when suckers arise from the base of the mother plant. Type 2 was the common type, accounting for 56 out of 72 palms. We did not find any association between suckering pattern and trunk volume. The following traits were found to be highly significantly correlated with trunk volume: trunk height, trunk diameter and leaf scar distance