Intra-annual stem diameter growth of Tamarix ramosissima and association with hydroclimatic factors in the lower reaches of China's Heihe River

High-resolution observations of cambial phenology and intra-annual growth dynamics are useful approaches for understanding the response of tree growth to climate and environmental change. During the past two decades, rapid socioeconomic development has increased the demand for water resources in the oases of the middle reaches of the Heihe River in northwestern China, and the lower reaches of the Heihe River have changed from a perennial river to an ephemeral stream with a decreased and degraded riparian zone. Tamarisk（Tamarix ramosissima） is the dominant shrub species of the desert riparian forest. In this study, the daily and seasonal patterns of tamarisk stem diameter growth, including the main period of tree ring formation, were examined. Observations concerning the driving forces of growth changes, along with implications for the ecology of the dendrohydrological area and management of desert riparian forests in similar arid regions, are also presented. The diurnal-seasonal activity of stem diameter and the dynamics of growth ring formation were studied using a point dendrometer and micro-coring methods during the 2012 growing season in shrub tamarisk in a desert riparian forest stand in the lower reaches of the Heihe River in Ejin Banner, Inner Mongolia of northwestern China. Generally, the variation in diurnal diameter of tamarisk was characterized by an unstable multi-peak pattern, with the cumulative stem diameter growth over the growing season following an S-shaped curve. The period from late May to early August was the main period of stem diameter growth and growth-ring formation. Among all of the hydroclimatic factors considered in this study, only groundwater depth was significantly correlated with stem diameter increment during this period. Therefore, for the dendrochronological study, the annual rings of the tamarisk can be used to reconstruct processes that determine the regional water regime, such as river runoff and fluctuations in groundwater depth. For the management of desert riparian forests, suitable groundwater depths must be maintained in the spring and summer to sustain tree health and a suitable stand structure.

Suitability of Stem Diameter Variations as an Indicator of Water Stress of Cotton

Water stress effects on stem diameter variations （SDV） were studied in a pot experiment on cotton （Gossypium hirustum L. Meimian99B）. Water restriction was imposed at the flowering stage and were compared with a well-watered control treatment. The volumetric soil water content （0v） and SDV were monitored continuously. The objective was to determine the feasibility of using the parameters derived from stem diameter measurements, including maximum daily stem shrinkage （MDS）, maximum daily stem diameter （MXSD）, and minimum daily stem diameter （MNSD） as indicators of plant water stress. The different behavior of SDV was founded at different growth stages. At stem-maturing stage, MDS increased and MNSD decreased in deficit-irrigated plants compared with the control plants, therefore, it appeared that MDS and MNSD ccould be used as available indicators of plant water status. At stem growth stage, there were no significant differences in MDS values between treatments but MXSD and MNSD responded sharply to soil water deficits. Thus, for rapidly growing cotton, the course of MXSD or MNSD with time offered a consistent stress indicator. SDV was also closely related to atmospheric factors, solar radiation （Rs） and vapor pressure deficit （VPD） were found to be the predominant factors affecting MDS, followed by the relative humidity （RH）, while air temperature （Ta） and wind velocity had the least effect. A good linear relationship was founded （r^2 = 0.921） between MDS and environmental variables （Rs, VPD, RH, and θv）, which can be used to establish a reference value for detecting plant water stress based on the MDS patterns.

Design and test of stem diameter inspection spherical robot

Stem diameter is an important parameter in the process of plant growth which can indicate the growth state and moisture content of the plant,its automatic detection is necessary.Traditional devices have many drawbacks that limit their practical uses in general case.To solve those problems,a stem diameter inspection spherical robot was developed in this study.The particular mechanism of the robot has turned out to be suitable for performing monitoring tasks in greenhouse mainly due to its spherical shape,small size,low weight and traction system that do not produce soil compacting or erosion.The mechanical structure and hardware architecture of the spherical robot were described,the algorithm based on binocular stereo vision was developed to measure the stem diameter of the plant.The effectiveness of the prototype robot was confirmed by field experiments in a tomato greenhouse.The results showed that the machine measurement data was linearly correlated with the manual measurement data with R^(2) of 0.9503.There was no significant difference for each attribute between machine measurement data and manual measurement data(sig>0.05).The results showed that this method was feasible for nondestructive testing of the stem diameter of greenhouse plants.

Comparison of stem taper models for the four tropical tree species in Mount Makiling, Philippines

This study was conducted to evaluate the performance of six stem taper models on four tropical tree species, namely Celtis luzonica(Magabuyo),Diplodiscus paniculatus(Balobo), Parashorea malaanonan(Bagtikan), and Swietenia macrophylla(Mahogany) in Mount Makiling Forest Reserve(MMFR), Philippines using fit statistics and lack-of-fit statistics. Four statistical criteria were used in this study, including the standard error of estimate(SEE),coefficient of determination(R^2), mean bias( E),and absolute mean difference(AMD). For the lack-offit statistics, SEE, E and AMD were determined in different relative height classes. The results indicated that the Kozak02 stem taper model offered the best fit for the four tropical species in most statistics. The Kozak02 model also consistently provided the best performance in the lack-of-fit statistics with the best SEE, E and AMD in most of the relative height classes. These stem taper equations could help forest managers and researchers better estimate the diameter of the outside bark with any given height,merchantable stem volumes and total stem volumes of standing trees belonging to the four species of thetropical forest in MMFR.

Evaluation of Some Stem Taper Models for Camellia japonica in Mount Halla, Korea

This study was conducted to evaluate the performance of the four stem taper models on Camellia japonica in Jeju Island, Korea using fit statistics and lack-of-fit statistics. The five statistical criteria that were used in this study were standard error of estimate(SEE), mean bias( E), absolute mean difference(AMD), coefficient of determination(R2), and root mean square error(RMSE). Results showed that the Kozak model 02 stem taper had the best performance in all fit statistics(SEE: 3.4708, E : 0.0040 cm, AMD : 0.9060 cm, R2 : 0.9870, and RMSE : 1.2545). On the other hand, Max and Burkhart stem taper model had the poorest performance in each statistical criterion(SEE: 4.2121, E : 0.2520 cm, AMD : 1.1300 cm, R2 : 0.9805, and RMSE: 1.5317). For the lack-of-fit statistics, the Kozak model 02 also provided the best performance having the best AMD in most of the relative height classes for diameter outside bark prediction and in most of the DBH classes for total volume prediction while Max and Burkhart had the poorest performance. These stem taper equations could help forest managers to better estimate the diameter outside bark at any given height, merchantable stem volumes and total stem volumes of the standing trees of Camellia japonica in the forests of Jeju Island, Korea.

Response of photosynthesis,growth,and acorn mass of pedunculate oak to diff erent levels of nitrogen in wet and dry growing seasons

The objective was to examine the effects of optimal leaf nitrogen levels>2.0%and suboptimal levels<2.0%,nitrogen nutrition on net photo synthetic rate,stem diameter increment,height growth increment and acorn mass of pedunculate oak during 2010 in the absence of drought stress and during 2011 under the impact of moderate drought stress.According to the results,moderate drought stress significantly reduced net photo synthetic rate,stem diameter increment and height growth increment,while acorn mass was not affected.Suboptimal nitrogen nutrition significantly reduced the net photo synthetic rate and stem diameter increment only in the wet year,acorn mass in both wet and dry years,while height growth increment was not significantly reduced by suboptimal nitrogen nutrition in either year.The results indicate that optimal nitrogen levels can stimulate photo synthetic rate and stem diameter increment of pedunculate oak only in the absence of moderate drought stress.Moreover,the results show that moderate drought stress is a more dominant stressor for photosynthesis and growth of pedunculate oak than suboptimal nitrogen nutrition,while for acorn development,it is the more dominant stressor.

Biomass Prediction Equation for Colophospermum mopane (Mopane) in Botswana

This study aimed to develop a biomass equation for estimating the total above-ground biomass for Colophospermum mopane (mopane) based on the pooled data from three study sites. The mopane woodlands in Botswana represent 14.6% of Botswana’s total area. The woodlands directly or indirectly support the livelihood of the majority of the rural population by providing wood and non-wood products. However, there is limited information on the pattern, trends and distribution of woody biomass production and their primary, environmental, and climatic determinants in different parts of Botswana. All the data were collected by destructive sampling from three study sites in Botswana. Stratified random sampling was based on the stem diameter at breast height (1.3 m from the ground or Diameter at Breast Height (DBH)). A total of 30 sample trees at each study site were measured, felled and weighed. The data from the three sites were pooled together, and the study employed regression analysis to examine the nature of relationships between total above-ground biomass (dependent variable) and five independent variables: 1) total tree height;2) crown diameter;3) stem diameters at 0.15 m;1.3 m (DBH) and 3 m from the ground respectively. There were significant relationships between all the independent variables and the dependent variable. However, DBH emerged as the strongest predictor of total tree above-ground biomass for mopane. The equation lnBiomass=-1.163+2.190lnDBH was adopted for use in the indirect estimation of total tree above-ground biomass for mopane in Botswana.

Monitoring of Growth Parameters of Sweet Corn Using CGMD302 Spectrometer

[Objective] This study aimed to clarify the quantitative relationships between growth parameters of sweet corn at different growth stages and canopy spectral indices,thus providing references for rapid monitoring of growth parameters of sweet corn.[Method] Based on field experiments of Zhengtian 68 under different potassium application levels,canopy spectral reflectance was collected using CGMD302 spectrometer at jointing stage,big bell mouth stage and tasseling stage,respectively;plant height,stem diameter,and leaf area index（LAI） were measured,to investigate the relationships between various growth parameters and spectral indices.[Result] Normalized difference vegetation index（NDVI） was positively correlated with stem diameter and LAI;ratio vegetation index（RVI） was negatively correlated with stem diameter and LAI.The single-stage monitoring models established based on NDVI and RVI could retrieve effectively stem diameter and LAI of sweet corn with the prediction accuracy of higher than 0.9,root mean square error（RMSE） of less than 10%,average relative error（RE） of less than 5%.[Conclusion] This study provided a technical basis for rapid monitoring of growth parameters of sweet corn.

Molecular Mapping of QTLs for Yield and Yield-Related Traits in Oryza sativa cv Swarna × O. nivara (IRGC81848) Backcross Population

Advanced backcross QTL analysis was used to identify QTLs for seven yield and yield-related traits in a BC2F2 population from the cross between a popular Oryza sativa cv Swarna and O. nivara IRGC81848. Transgressive segregants with more than 15% increased effect over Swarna were observed for all the traits except days to heading and days to 50% flowering. Thirty QTLs were detected for seven yield and yield-related traits using interval and composite interval mapping. Enhancing alleles at 13 (45%) of these QTLs were derived from O. nivara, and enhancing alleles at all the QTLs for stem diameter and rachis diameter were derived from O. nivara. Three stem diameter QTLs, two rachis diameter QTLs and one number of secondary branches QTL identified by both Interval and composite interval mapping contributed more than 15% of the total phenotypic variance. The QTL epistasis was significant for stem diameter and plot yield. The most significant QTLs qSD7.2, qSD8.1 and qSD9.1 for stem diameter, qRD9.1 for rachis diameter and qNSB1.1 for number of secondary branches are good targets to evaluate their use in marker-assisted selection. O. nivara is a good source of novel alleles for yield related traits and reveals major effect QTLs suitable for marker-assisted selection.

Comparison of the influences of vegetation stem parameters on hydraulic variables and sediment transport capacity

The hydraulic variables(Hv)and sediment transport capacity(Tc)of overland flow have changed immensely due to large-scale revegetation.However,research comparing the influences of stem pa-rameters(diameter,cover,and arrangement)on Hv and Tc is limited.The objectives of this study were to explore and compare the influences of stem parameters on Hv and Tc.Data on three treatment groups with varying stem diameters,covers,arrangements,flow discharges and slopes were collected in this study.With increasing stem diameter,Hv and Tc increased;Hv included the Reynolds and Froude numbers,flow velocity(v),shear stress(τ),stream power(Ω),and unit stream power(ω).However,the trend of the Darcy-Weisbach friction coefficient(f)was opposite.Hv and Tc were significantly influenced by stem diameter and cover.The effect of stem diameter on Hv and Tc was greater than the effects of cover and arrangement.Stem cover as a variable could not be used to adequately estimate the Tc when there were various stem diameters.A new exponential equation involving stem cover and stem diameter was demonstrated to be an appropriate predictor of Tc.Stem diameter and arrangement had no obvious influence on the relationship between Tc and v,and v as an indicator could explain the effect of stem parameters on Hv and Tc.This result could illustrate why the variables,including v,were able to predict Tc under vegetation stem and litter cover.

Evaluation of Drought and High Temperature Resistances in Cowpea （Vigna unguiculata （L.） Walpers） for Sahel, Africa

Physiological responses were studied in temperature-controlled glass house at Okinawa, Japan to evaluate drought and high temperature resistances of cowpea cultivar/strains for Sahel, Africa. Four drought-tolerant cowpea cultivar/strains （cv. TVu-11986; TVu-11979; IT-96D-604 and Dan Ilia）, and three sensible strains （cv. IT96K-238-3, IT96K-231-1 and TVu-7778） were grown in pots and imposed to drought （soil content; 9.7±1.9%（w/w））, high （30/26℃, day/night, 12/12 hour）, normal （27/23℃, control） and low （24/20℃） temperature conditions after flowering. Plant fresh weight reduced 80%, 26% and 1% by dry, high and low temperature, respectively. Stem diameter decreased 32% and 2% by dry and low temperature, respectively, but increased 5% by high temperature. Difference between the drought tolerant and sensible cultivars/strains, pre-evaluated by IITA, was explained by relationship between stem diameter and plant fresh weight with 77% of reliability. The 35% of misclassification were due to misjudgment of drought tolerant as sensible in dry plot. The stem diameter highly correlated with all parts of plant weight in all regimes except in dry treatment. Difference of the classification between IITA and our results may cause different survival strategy against drought. The cultivars/strains, evaluated as drought tolerant by IITA, might fatten up at early stage, and could avoid from drought at latter growing stage.

Habitat use by mountain nyala Tragelaphus buxtoni determined using stem bite diameters at point of browse, bite rates, and time budgets in the Bale Mountains National Park, Ethiopia

We studied the habitat use of mountain nyala Tragelaphus buxtoni in the northern edge of the Bale Mountains Na- tional Park, Ethiopia. The aims of this study were to： （1） measure and quantify habitat-specific stem bite diameters of mountain nyala foraging on common natural plant species in two major habitat types （i.e. grasslands versus woodlands）, and （2） quantify the bite rates （number of bites per minute） and the activity time budgets of mountain nyala as functions of habitat type and sex-age category. We randomly laid out three transects in each habitat type. Following each transect, through focal animal obser- vations, we assessed and quantified stem diameters at point of browse （dpb）, bite rates, and time budgets of mountain nyala in grasslands versus woodlands. Stem dpb provide a measure of natural giving-up densities （GUDs） and can be used to assess fora- ging costs and efficiencies, with greater stem dpb corresponding to lower costs and greater efficiencies. The results showed that stem dpb, bite rates, induced vigilance, and proportion of time spent in feeding differed between habitats. In particular, mountain nyala had greater stem dpb, higher bite rates, and spent a greater proportion of their time in feeding and less in induced vigilance in the grasslands. In addition, adult females had the highest bite rates, and the browse species Solanum marginatum had the greatest stem dpb. Generally, grasslands provide the mountain nyala with several advantages over the woodlands, including of- fering lower foraging costs, greater safety, and more time for foraging. The study advocates how behavioural indicators and natural GUDs are used to examine the habitat use of the endangered mountain nyala through applying non-invasive techniques. We conclude that the resulting measures are helpful for guiding conservation and management efforts and could be applicable to a number of endangered wildlife species including the mountain nyala .

Oxygation Enhances Growth,Gas Exchange and Salt Tolerance of Vegetable Soybean and Cotton in a Saline Vertisol

Impacts of salinity become severe when the soil is deficient in oxygen. OxygaUon （using aerated water for subsurface drip irrigation of crop） could minimize the impact of salinity on plants under oxygen-limiting soil environments. Pot experiments were conducted to evaluate the effects of oxygation （12% air volume/volume of water） on vegetable soybean （moderately salt tolerant） and cotton （salt tolerant） in a salinized vertisol at 2, 8, 14, 20 dS/m ECe. In vegetable soybean, oxygation increased above ground biomass yield and water use efficiency （WUE） by 13% and 22%, respectively, compared with the control. Higher yield with oxygation was accompanied by greater plant height and stem diameter and reduced specific leaf area and leaf Na^＋ and CI^- concentrations. In cotton, oxygation increased lint yield and WUE by 18% and 16%, respectively, compared with the control, and was accompanied by greater canopy light interception, plant height and stem diameter. Oxygation also led to a greater rate of photosynthesis, higher relative water content in the leaf, reduced crop water stress index and lower leaf water potential. It did not, however, affect leaf Na^＋ or CI^- concentration. Oxygation invariably increased, whereas salinity reduced the K^＋： Na^＋ ratio in the leaves of both species. Oxygation improved yield and WUE performance of salt tolerant and moderately tolerant crops under saline soil environments, and this may have a significant impact for irrigated agriculture where saline soils pose constraints to crop production.