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.

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.

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.