Effect of Grafting Dates on Graft-take Success and Sapling Growth of Persian Walnut (Juglans regia L.) Under Open Field Condition of Jumla, Nepal

A field experiment was carried out at Horticultural Research Station, Rajikot, Jumla to determine the best grafting date of walnut for the highest graft-take success and sapling growth. The experiment was conducted during the two consecutive years 2017, and 2018. Two varieties namely ‘Hartley’ and ‘Payne’ and four different dates of grafting viz. 15th March, 22nd March, 29th March, and 5th April were used as the treatment and the experiment was laid out in split-plot design. Each treatment was assigned with ten grafts with five replications per treatment. The measured parameters for the experiments included graft-take success (%), final scion diameter (cm), growth on scion diameter (%), number of primary branches per plant, plant spread (cm), and number of leaf per plant. The pooled value of observation for two years showed highly significant effect of variety and grafting date on grafting-take. ‘Hartley’ variety showed maximum graft-take success (73.2%) and ‘Payne’ with the least success (54.0%). The pooled value of two successive years showed the highest graft-take success (70.0%) on 15th of March, significantly at par with 22nd March (64.5%) and 29th March (67.0 %) grafting. Grafting on 15th March was also superior in terms of number of leaves (31.7), and least was observed for grafting on 29th March (20.5). In essence, variety ‘Hartley’ was found to record higher graft-take success with 15th March as the optimum grafting date under Jumla condition.

Adaptive Management Lessons for Serianthes nelsonii Conservation

The literature covering the biology, ecology, horticulture, and conservation of the critically endangered tree Serianthes nelsonii Merr. was reviewed. The roots, stems, and leaves of this charismatic legume tree revealed highly plastic traits and responded positively to horticultural manipulations to improve the quality of container-grown transplants. Pre-sowing seed treatments of seed coat scarification and 1 h of imbibition generated 85% to 90% germination at a temperature optimum of 26 °C. Adventitious root formation on air layers and successful unions on approach grafts were 100%. Seedling and sapling growth was maximum under 25% to 50% sunlight transmission, limited irrigation to ensure adequate root zone aeration, repetitive stem tip pruning to increase root:shoot quotient, and thigmic stress to retain an orthotropic orientation of stems. In situ regeneration on Guam was substantial but recruitment from seedling to sapling was nil. High quality leaf litter chemistry enabled rapid decomposition, and soils beneath the tree exhibited unique chemical traits that increased ecosystem health by creating spatial heterogeneity. The greatest unanswered questions focus on plant mortality. Research is needed to determine the reasons for the mortality of in situ seedlings, mortality within transplantation projects on Guam, and the mortality of 60% of the mature in situ tree population during the 26-year implementation of the national recovery plan. Horticultural researchers are ideally positioned to answer these urgent questions.

The influence of two wildfires and biological control agents on the population dynamics of Melaleuca quinquenervia in a seasonally inundated wetland

The potential of Melaleuca quinquenervia (Cav.) S.T. Blake to reinvade cleared areas was evaluated over a 13-yr period that included two wildfires and the introduction of biological control agents. The first wildfire occurred in 1998 and was followed by a mean of 591.5 recruited seedlings m−2. Recruits from that fire were cleared 7 yr later in July 2005 for a second experiment to evaluate seedling recruitment into cleared areas. Seed rain, seedling recruitment and mortality, and sapling growth rates were measured in four plots located around individual large reproductive trees. A second natural wildfire in 2007 burned through those plots, leading to increases in seed rain followed by a pulse in recruitment of 21.04 seedlings m−2, 96.5% fewer than after the 1998 fire. Recruits in half of the plots around each tree were then treated with regular applications of an insecticide to restrict herbivory by biological control agents, while herbivory was not restricted in the other half. There was no difference in seedling mortality between treatments 1,083 d post-fire (2007) with 96.6% seedling mortality in the unrestricted herbivory treatment and 89.4% mortality in the restricted herbivory treatment. Recruits subjected to the restricted herbivory treatment grew taller than those in the unrestricted herbivory treatment, 101.3 cm versus 37.4 cm. Many of the recruits were attacked by the biological control agents, which slowed their growth. Although solitary M. quinquenervia trees retain some capacity to reinvade areas under specific circumstances, there was a downward trend in their overall invasiveness at this site, with progressively smaller recruitment cohorts due to biological control agents. Land managers should prioritize removing large reproductive trees over treating recently recruited populations, which can be left for many years for the biological control agents to suppress before any additional treatment would be needed.

Sapling and coppice biomass heritabilities and potential gains from Eucalyptus polybractea progeny trials

Eucalyptus polybractea has been planted as a short-rotation coppice crop for bioenergy in Western Australia. Historical breeding selections were based on sapling biomass and despite a long history as a coppice crop, the genetic parameters of coppicing are unknown. Here, we assessed sapling biomass at ages 3 and 6 from three progeny trials across southern Australia. After the second sapling assessment, all trees were harvested. Coppice biomass was assessed 3.5 years later. Mortality following harvest was between 1 and 2%. Additive genetic variance for the 6-sapling estimate at one site was not significant. Sapling heritabilities were between 0.06 and 0.36 at 3 years, and 0.18 and 0.20 at 6 years. The heritability for the coppice biomass was between 0.07 and 0.17. Within-site genetic and phenotypic correlations were strong between all biomass assessments. Cross-site correlations were not different from unity. Selections based on net breeding values revealed positive gains in sapling and coppice biomass. Lower or negative gains were estimated if 3-year sapling selections were applied to the coppice assessments (−7.1% to 3.4%) with useful families culled. Positive gains were obtained if 6-year sapling selections were applied to the coppice assessment (6.4% to 9.3%) but these were lower than those obtained by applying coppice selections to the coppice assessment (8.4% to 14.8%). Removal of poor performing families and families that displayed fast sapling growth rates but under-performed as coppice will benefit potential coppice production. These results indicate that selections should be made using coppice data.

Influence of spacing and seed trees on the growth of Pericopsis elata saplings during the first twenty months of a planting trial

Description of the subject. Pericopsis elata (Fabaceae) is a long-lived light-demanding tree from African rain forests that produces timber of high economic value. Natural populations suffer from overexploitation and a deficit of natural regeneration. Plantations could increase its production and limit the pressure on natural forests. However, we lack knowledge on the influence of spacing and seed tree origin on tree growth to optimize plantation protocols. Objectives. This study evaluated the impact of sapling density and seed tree origin on the growth in diameter and height of P. elata plants, 20 months after plantation. Method. Seeds were collected on 19 mother trees in a 400 ha natural stand near Kisangani (DRC). In October 2017, seedlings were transplanted in a Nelder design plantation with three replicates, to compare sapling growth at 10 contrasting plant densities under full sun. Diameter and height increments of 540 plants were analyzed according to local competition and maternal origin using generalized additive models. Results. Twenty months after planting, height growth peaked at an intermediate density of 47,000 stems·ha-1 (165.6 ± 39.2 cm·year-1), while diameter growth peaked at a lower density of 4,200 stems·ha-1 (24.6 ± 8.3 mm·year-1). The maternal origin of saplings affected their growth, the coefficients of variation among mother trees reaching 7.6% and 6.4% for diameter and height increments, respectively. The initial diameter affected positively diameter growth while the initial height did not influence height growth. Conclusions. The Nelder design proved useful to assess how plant growth depends both on spacing and genetic factors.

Determination of the Development Performances of Pecan Saplings in Aydin ecological Conditions

In this research, the sapling growth performances of Pecan cultivation in Aydın ecological conditions were investigated. "Burkett" Pecan rootstock and "Mahan14", "Wichita7" and "Choctaw2" pecan cultivars were used. Starting from the date of planting; Sapling stem diameters were measured 5 cm above the graft site. Diameters of rootstocks was measured 5 cm below the graft site, bud burst dates are determined (min %70 of buds), shoot diameters were measured at 15-day intervals from the place after the first two buds. Shoot lengths were measured at 15-day intervals. The measurements were carried out for 2 consecutive years. Repeared Measures Anova is used to determine whether there are significant differences in the data. The development difference between cultivars in both regions was investigated. In the analysis, averages of five replicate measurements in two years and 12 different periods. Pecan saplings showed a good development in the ecological conditions of Aydin (37°45′ 0″N - 28°0′0″E). These results show that in the province of Aydın, Pecan cultivation can be done except in very cold and very dry places. However, the study should be supported by future fruit productivity studies. The present research findings will be useful for regions with similar climatic conditions.

Struktur dan Asosiasi Vegetasi Mangrove di Hilir DAS Torue, Parigi Moutong, Sulawesi Tengah (Structure and Association of Mangrove Vegetation in Torue Watershed Downstream, Parigi Moutong, Central Sulawesi)

One important aspect needed in mangrove forest management was the data and information available regarding structure and associations. However, the structure and association of mangrove forests in the Torue watershed downstream had not been identified. The purpose of this research was to evaluate the structure and association of mangrove forests in the Torue watershed downstream. This research used the plot path method with a path and plot combination. Path placement was done by purposive sampling. The results showed that the mangrove forest structure of the Torue watershed downstream consisted of three canopy layers, i.e., Stratum C, D, and E, which were dominated by seedling and sapling growth rates. Stratum C was dominated by Sonneratia alba type, and Stratum D was dominated by Bruguiera gymnorizha and Bruguiera sexangula types. In contrast, Stratum E was dominated by Rhizophora mucronata and Rhizophora apiculata types. There was no association between mangrove vegetation and all species. However, three pairs of species had a positive association coefficient, namely: Sonneratia alba with Rhizophora apiculata with a coefficient value of 0,42, Rhizophora mucronata with Bruguiera gymnorhiza, and Rhizophora mucronata with Bruguiera sexangula each coefficient value of 0,06, which was not associated with five species, namely Sonneratia alba, Rhizophora mucronata, Rhizophora apiculata, Bruguiera gymnorizha, and Bruguiera sexangula. The results of this study could be the basis of the guidelines for sustainability in mangrove forest management.Keywords: association, mangrove forest, vegetation structure, watershed

Effects of Experimental Throughfall Exclusion on Soil Respiration in a Continental Coniferous Stand, South Korea

Severe droughts and changing precipitation patterns could alter the biogeochemical properties of the soil, affecting soil carbon cycles in forest ecosystems. A throughfall exclusion (TFE) experiment was conducted in a continental climate coniferous stand in Gangwon Province, Korea, to examine the effects of excluding rainfall on total soil respiration (SR), heterotrophic soil respiration (HR), autotrophic soil respiration (AR), sapling diameter growth, and soil bacterial communities from July 2016 to October 2017. The soil water content (SWC) was significantly decreased by the exclusion of the throughfall, resulting in changes in the bacterial communities, and subsequently a decrease in HR. Although AR did not present significant differences between the control and TFE plots, the rate of sapling growth was significantly lower in the TFE plots compared with that in the control plots. An exponential function relating SR to soil temperature accounted for 0.61% and 0.82% of the variance in SR in the control and TFE plots, respectively (Q10 = 2.48 and 2.86, respectively). Furthermore, a multivariate nonlinear model based on soil temperature and SWC explained 0.89% and 0.88% of the variance in SR in the control and TFE plots, respectively. When soil temperature was high, SR showed high fluctuations due to SWC variation. However, when SWC was low, we detected relatively small fluctuations in SR due to soil temperature. The results of this study show that the activity of soil microbial and root respiration during the growing season may be lower under future drought conditions.

Komposisi Jenis Tumbuhan dan Analisis Sebaran Langkap (Arenga obtusifolia Mart.) di Taman Nasional Ujung Kulon

Langkap (Arenga obtusifolia) is one of the species of the Arenga clan, which has a wide distribution in Ujung Kulon National Park (UKNP). The aim of study was to determine the pattern of spreading langkap in order to support the management of Javan Rhino habitat. The vegetation analysis method used is a combination method between the line method and the path method. Langkap is the dominant species in UKNP at the sapling growth rate, with a density of 480-624 individuals/ha and INP value of 61.47% -78.30%, while the catch density at seedling growth rate is 900- 2,200 individuals/ha with INP value of 21.31% -49.41%. The standard Morisita coefficient value of langkap in each research block and growth rate is obtained in the range of values (-0.32) - 0.51, the spreading pattern shows a clustered spread pattern (Ip> 0) and uniform (Ip <0). The tendency of langkap domination in the research block can be seen from the ratio of catch density compared to the total density or its relative density at various growth rates. This shows that in the dominant catchment area there is a reduction in the density of plants other than langkap, especially the Javan Rhino feed plants.