title: Water requirements for 'Hass' avocado flowering and fruit development in New Zealand

authors: Kaneko, Teruko

subjects: avocado

abstract: The aim of this work was to determine water requirements for Persea americana 'Hass’ avocado trees (mature, ca. 9 years and young, ca. 3 years) from November 2014 to October 2015 in Bay of Plenty, New Zealand. In addition, the effect of water deficit on flowering and early fruit development was investigated in young avocado (ca. 3 years) trees. 

Reference evapotranspiration (ETo) was calculated by the FAO Penman-Monteith equation based on weather information at the orchard. Crop evapotranspiration (ETc) of avocado was measured by sap flow measurements using the compensation heat pulse method (CHPM), and daily crop evapotranspiration was also estimated from a soil water balance (Ewb). Avocado tree water requirements were calculated as crop coefficients (Kc - the ETo/ETc ratio).
•	Monthly cumulative ETo showed a gradual reduction from 145.9 mm in January to 297.7 mm in June. Monthly cumulative ETc for both the mature and young plants was highest at 75 and 41.8 mm in January, and the lowest at 22.4 and 13.53 mm in July, respectively. The results showed a close correlation between ETc and ETo. 
•	Ewb was higher than ETc by 22 % for the mature and 55 % for the young plants, probably caused by drainage which was not measured.
•	In summer, monthly average Kc varied between 0.45-0.60 for the mature and 0.25-0.30 for the young plants. In winter, Kc increased to 0.9-1.0 for the mature and 0.45-0.55 for the young plants.   

To investigate the effect of water deficit on flowering and fruit development, rainout shelters were set up under the young trees from mid-October 2014. During this treatment, the control plants were well irrigated and fertilized, while the drought plants received no irrigation, precipitation, or fertilizers. The rainout shelters were removed in early-May 2015, and monitoring was continued until late-October.
•	During the rainout treatment, at a depth of 0-30 cm, soil water contents of the drought treated plants dropped to 0.13 m3/m3, while that of the control remained above 0.2 m3/m3. However, from March, soil water content of the drought plants was stable at 0.20 m3/m3 at a depth of 31-60 cm and 0.25 m3/m3 at a depth of 61-90 cm. Spatial soil moisture demonstrated the soil was  drier close to the drought treated trees, but wetter near the edge of the rainout shelters. These measurements suggest the drought plants were able to obtain some water from the deeper soil or outside the shelters. 
•	Predawn leaf water potential (PLWP) of the drought plants was lower by 0.06-0.22 MPa than that of the control plants during the flowering season. However, in December, there was no significant difference in stomatal conductance (gs) between the two treatments. The drought leaf water potential (LWP) and stem water potential (SWP) were more negative than the control LWP and SWP. In January and February, the drought LWP and SWP dropped to -0.43 MPa and -0.30 MPa, whereas the control LWP and SWP were around -0.25 MPa and -0.23 MPa, respectively, assuming the rainout shelters caused moderate water stress in the drought-treated plants.
•	Throughout the flowering season, in total, 1382 open female flowers on the control plants and 1515 flowers on the drought plants were marked and their fates monitored. About 21 % of control flowers and 23 % of the drought flowers remained on the tree 16 days after anthesis. 100 days after anthesis, only 4 control and 1 drought fruit from the monitored flowers were retained on the plants. 
•	The two treatments had significant fruit drop in summer, about 70 % of marked fruit dropped in January and February, and a second peak of fruit abscission occurred in winter, caused by frost. At harvest, the retention rate of fruit for the control and drought treatments were 15 % and 5 %, respectively. Moreover, the drought plants had smaller fruit size than fruit of the control plants by 21 % at harvest. The differences in fruit abscission and fruit size were probably caused by the combined effects of water deficit, nutrient deficiency, and crop load. 
•	The control had higher average yield at 36.4 ± 1.1 kg per plant than the drought plants at 27.8 ± 1.0 kg per plant. The dry matter content of the control fruit was 30.4 ± 0.3 %, 7% higher than that of the drought fruit. 

The results can be used to develop irrigation recommendations, and that under the conditions described here the trees were difficult to drought stress in spring and flowering did not appear to be very sensitive to drought stress. However, early fruit growth was very sensitive to water deficits, resulting in a large reduction in fruit size.

text: Water requirements for 'Hass' avocado flowering and fruit development in New Zealand The aim of this work was to determine water requirements for Persea americana 'Hass’ avocado trees (mature, ca. 9 years and young, ca. 3 years) from November 2014 to October 2015 in Bay of Plenty, New Zealand. In addition, the effect of water deficit on flowering and early fruit development was investigated in young avocado (ca. 3 years) trees. 

Reference evapotranspiration (ETo) was calculated by the FAO Penman-Monteith equation based on weather information at the orchard. Crop evapotranspiration (ETc) of avocado was measured by sap flow measurements using the compensation heat pulse method (CHPM), and daily crop evapotranspiration was also estimated from a soil water balance (Ewb). Avocado tree water requirements were calculated as crop coefficients (Kc - the ETo/ETc ratio).
•	Monthly cumulative ETo showed a gradual reduction from 145.9 mm in January to 297.7 mm in June. Monthly cumulative ETc for both the mature and young plants was highest at 75 and 41.8 mm in January, and the lowest at 22.4 and 13.53 mm in July, respectively. The results showed a close correlation between ETc and ETo. 
•	Ewb was higher than ETc by 22 % for the mature and 55 % for the young plants, probably caused by drainage which was not measured.
•	In summer, monthly average Kc varied between 0.45-0.60 for the mature and 0.25-0.30 for the young plants. In winter, Kc increased to 0.9-1.0 for the mature and 0.45-0.55 for the young plants.   

To investigate the effect of water deficit on flowering and fruit development, rainout shelters were set up under the young trees from mid-October 2014. During this treatment, the control plants were well irrigated and fertilized, while the drought plants received no irrigation, precipitation, or fertilizers. The rainout shelters were removed in early-May 2015, and monitoring was continued until late-October.
•	During the rainout treatment, at a depth of 0-30 cm, soil water contents of the drought treated plants dropped to 0.13 m3/m3, while that of the control remained above 0.2 m3/m3. However, from March, soil water content of the drought plants was stable at 0.20 m3/m3 at a depth of 31-60 cm and 0.25 m3/m3 at a depth of 61-90 cm. Spatial soil moisture demonstrated the soil was  drier close to the drought treated trees, but wetter near the edge of the rainout shelters. These measurements suggest the drought plants were able to obtain some water from the deeper soil or outside the shelters. 
•	Predawn leaf water potential (PLWP) of the drought plants was lower by 0.06-0.22 MPa than that of the control plants during the flowering season. However, in December, there was no significant difference in stomatal conductance (gs) between the two treatments. The drought leaf water potential (LWP) and stem water potential (SWP) were more negative than the control LWP and SWP. In January and February, the drought LWP and SWP dropped to -0.43 MPa and -0.30 MPa, whereas the control LWP and SWP were around -0.25 MPa and -0.23 MPa, respectively, assuming the rainout shelters caused moderate water stress in the drought-treated plants.
•	Throughout the flowering season, in total, 1382 open female flowers on the control plants and 1515 flowers on the drought plants were marked and their fates monitored. About 21 % of control flowers and 23 % of the drought flowers remained on the tree 16 days after anthesis. 100 days after anthesis, only 4 control and 1 drought fruit from the monitored flowers were retained on the plants. 
•	The two treatments had significant fruit drop in summer, about 70 % of marked fruit dropped in January and February, and a second peak of fruit abscission occurred in winter, caused by frost. At harvest, the retention rate of fruit for the control and drought treatments were 15 % and 5 %, respectively. Moreover, the drought plants had smaller fruit size than fruit of the control plants by 21 % at harvest. The differences in fruit abscission and fruit size were probably caused by the combined effects of water deficit, nutrient deficiency, and crop load. 
•	The control had higher average yield at 36.4 ± 1.1 kg per plant than the drought plants at 27.8 ± 1.0 kg per plant. The dry matter content of the control fruit was 30.4 ± 0.3 %, 7% higher than that of the drought fruit. 

The results can be used to develop irrigation recommendations, and that under the conditions described here the trees were difficult to drought stress in spring and flowering did not appear to be very sensitive to drought stress. However, early fruit growth was very sensitive to water deficits, resulting in a large reduction in fruit size.

year: 2016

title: Tree-based Density Estimation: Algorithms and Applications

authors: Schmidberger, Gabi

subjects: machine learning

abstract: Data Mining can be seen as an extension to statistics. It comprises the preparation
of data and the process of gathering new knowledge from it. The extraction of
new knowledge is supported by various machine learning methods. Many of the
algorithms are based on probabilistic principles or use density estimations for their
computations. Density estimation has been practised in the field of statistics for
several centuries. In the simplest case, a histogram estimator, like the simple equalwidth
histogram, can be used for this task and has been shown to be a practical
tool to represent the distribution of data visually and for computation. Like other
nonparametric approaches, it can provide a flexible solution. However, flexibility
in existing approaches is generally restricted because the size of the bins is fixed 
either the width of the bins or the number of values in them. Attempts have been
made to generate histograms with a variable bin width and a variable number of
values per interval, but the computational approaches in these methods have proven
too difficult and too slow even with modern computer technology.
In this thesis new flexible histogram estimation methods are developed and tested
as part of various machine learning tasks, namely discretization, naive Bayes classification,
clustering and multiple-instance learning. Not only are the new density
estimation methods applied to machine learning tasks, they also borrow design
principles from algorithms that are ubiquitous in artificial intelligence: divide-andconquer
methods are a well known way to tackle large problems by dividing them
into small subproblems. Decision trees, used for machine learning classification,
successfully apply this approach. This thesis presents algorithms that build density
estimators using a binary split tree to cut a range of values into subranges of
varying length. No class values are required for this splitting process, making it an
unsupervised method. The result is a histogram estimator that adapts well even to
complex density functions a novel density estimation method with flexible density
estimation ability and good computational behaviour.
Algorithms are presented for both univariate and multivariate data. The univariate
histogram estimator is applied to discretization for density estimation and
also used as density estimator inside a naive Bayes classifier. The multivariate histogram,
used as the basis for a clustering method, is applied to improve the runtime
behaviour of a well-known algorithm for multiple-instance classification. Performance
in these applications is evaluated by comparing the new approaches with
existing methods.

text: Tree-based Density Estimation: Algorithms and Applications Data Mining can be seen as an extension to statistics. It comprises the preparation
of data and the process of gathering new knowledge from it. The extraction of
new knowledge is supported by various machine learning methods. Many of the
algorithms are based on probabilistic principles or use density estimations for their
computations. Density estimation has been practised in the field of statistics for
several centuries. In the simplest case, a histogram estimator, like the simple equalwidth
histogram, can be used for this task and has been shown to be a practical
tool to represent the distribution of data visually and for computation. Like other
nonparametric approaches, it can provide a flexible solution. However, flexibility
in existing approaches is generally restricted because the size of the bins is fixed 
either the width of the bins or the number of values in them. Attempts have been
made to generate histograms with a variable bin width and a variable number of
values per interval, but the computational approaches in these methods have proven
too difficult and too slow even with modern computer technology.
In this thesis new flexible histogram estimation methods are developed and tested
as part of various machine learning tasks, namely discretization, naive Bayes classification,
clustering and multiple-instance learning. Not only are the new density
estimation methods applied to machine learning tasks, they also borrow design
principles from algorithms that are ubiquitous in artificial intelligence: divide-andconquer
methods are a well known way to tackle large problems by dividing them
into small subproblems. Decision trees, used for machine learning classification,
successfully apply this approach. This thesis presents algorithms that build density
estimators using a binary split tree to cut a range of values into subranges of
varying length. No class values are required for this splitting process, making it an
unsupervised method. The result is a histogram estimator that adapts well even to
complex density functions a novel density estimation method with flexible density
estimation ability and good computational behaviour.
Algorithms are presented for both univariate and multivariate data. The univariate
histogram estimator is applied to discretization for density estimation and
also used as density estimator inside a naive Bayes classifier. The multivariate histogram,
used as the basis for a clustering method, is applied to improve the runtime
behaviour of a well-known algorithm for multiple-instance classification. Performance
in these applications is evaluated by comparing the new approaches with
existing methods.

year: 2009

title: A Relationships Framework for Organisational Responsiveness to Te Tiriti/Treaty of Waitangi in the Work of Groups and Organisations in the Community and the Public Sector of Aotearoa New Zealand

authors: Spelman, Anthony Cyril

subjects: Organisation Development

abstract: This thesis is focussed on the development and implementation of a Relationships Framework based on Te Tiriti/Treaty of Waitangi.  The Framework has been designed to enable working together between Tangata Whenua and Tangata Tiriti in the community and Public Sector in Aotearoa New Zealand.  Its development is explored and its implementation critiqued.  Within that Framework, an original organisation development tool based on a Tiriti/Treaty two-worldview approach is examined in terms of its potential to facilitate change in the operation and management of public life in Aotearoa New Zealand.
My aim is to establish an effective approach for working with worldview difference in the context of Tiriti/Treaty of Waitangi relationships and their implications.  I have a belief that Tangata Whenua are currently excluded from participating in processes that govern public life due to the dominance of Tangata Tiriti worldviews.  Therefore I am committed to making a contribution to a change in this dynamic so that Tangata Whenua views are not only heard but form an integral part of how the infrastructure of our public life is developed and managed. 
The Tiriti/Treaty of Waitangi Relationships Framework [The Framework] presented in the thesis is critiqued in two ways: i) through an examination of the concepts that inform it, and ii) by exploring six examples of its operation and further development in the community and public sector in Aotearoa New Zealand.  The Framework and the Tiriti/Treaty Two-worldview approach used to inform it has worked effectively in a variety of settings.  Through my research I show that organisation development of this type is complex.  It appears that there need be no fixed starting point in the development process within an organisation.  However all key elements of that process must eventually be addressed if effective relationships are to be achieved and the resulting organisational change is to be sustained.  Commitment to organisation development of this type is therefore long-term and requires a commitment to leading and supporting change in behaviour, systems and processes, and structures.

text: A Relationships Framework for Organisational Responsiveness to Te Tiriti/Treaty of Waitangi in the Work of Groups and Organisations in the Community and the Public Sector of Aotearoa New Zealand This thesis is focussed on the development and implementation of a Relationships Framework based on Te Tiriti/Treaty of Waitangi.  The Framework has been designed to enable working together between Tangata Whenua and Tangata Tiriti in the community and Public Sector in Aotearoa New Zealand.  Its development is explored and its implementation critiqued.  Within that Framework, an original organisation development tool based on a Tiriti/Treaty two-worldview approach is examined in terms of its potential to facilitate change in the operation and management of public life in Aotearoa New Zealand.
My aim is to establish an effective approach for working with worldview difference in the context of Tiriti/Treaty of Waitangi relationships and their implications.  I have a belief that Tangata Whenua are currently excluded from participating in processes that govern public life due to the dominance of Tangata Tiriti worldviews.  Therefore I am committed to making a contribution to a change in this dynamic so that Tangata Whenua views are not only heard but form an integral part of how the infrastructure of our public life is developed and managed. 
The Tiriti/Treaty of Waitangi Relationships Framework [The Framework] presented in the thesis is critiqued in two ways: i) through an examination of the concepts that inform it, and ii) by exploring six examples of its operation and further development in the community and public sector in Aotearoa New Zealand.  The Framework and the Tiriti/Treaty Two-worldview approach used to inform it has worked effectively in a variety of settings.  Through my research I show that organisation development of this type is complex.  It appears that there need be no fixed starting point in the development process within an organisation.  However all key elements of that process must eventually be addressed if effective relationships are to be achieved and the resulting organisational change is to be sustained.  Commitment to organisation development of this type is therefore long-term and requires a commitment to leading and supporting change in behaviour, systems and processes, and structures.

year: 2013