title: The kiwifruit (Actinidia sp.) vine root system: Responses to vine manipulations

authors: Black, Marykate Z.

subjects: root

abstract: The root system is a significant component of whole-plant biomass in kiwifruit vines and is likely to be a considerable carbohydrate sink. Seasonal trends in root growth were investigated to infer seasonal fluctuations in root carbohydrate demand. Root growth peaked in summer and autumn. Observations indicate that peak root demand for carbohydrates occurs when fruit demands are also high. This infers competition between fruit and root growth, disagreeing with observations in other species. Carbohydrate partitioning between fruit and roots was studied in small kiwifruit plants using the tracer 14C. Simultaneous tracer import was observed into fruit and roots. When half the root system was cut off, root system import was reduced. The fruit imported a larger proportion of the available tracer, whilst there was no change in import into the remaining root half. Simultaneous carbohydrate import into fruit and roots demonstrated competition between these sinks. However, increased carbohydrate import into fruit suggests that the fruit has higher priority. The findings of this research suggest that the root system is a more competitive sink in kiwifruit vines than in some other fruit crops.
Trunk girdling and root pruning are used to improve kiwifruit vine productivity. The effects of these practices on vine physiology, and root growth and function were investigated. Girdling reduced photosynthesis, with reductions attributed to stomatal limitation and feedback inhibition. Repeat annual girdling reduced root biomass by approximately 59%. Root growth rates were not affected, however, girdled vines produced less root tips. This suggests that new root production is more of a carbon expense than root extension. Root pruning reduced whole-vine hydraulic conductance. As treatment severity increased, reduced photosynthesis was evident, attributed to reduced sink demand. Roots in other species have demonstrated rapid changes in hydraulic conductance in response to environmental stresses. Hydraulic conductance in intact roots of kiwifruit vines did not respond when 80% of root biomass was removed. However, sap flow increased to a rate approximately 50% higher than pre-treatment. Kiwifruit roots exhibited hydraulic redundancy, which may be a stress tolerance mechanism.

text: The kiwifruit (Actinidia sp.) vine root system: Responses to vine manipulations The root system is a significant component of whole-plant biomass in kiwifruit vines and is likely to be a considerable carbohydrate sink. Seasonal trends in root growth were investigated to infer seasonal fluctuations in root carbohydrate demand. Root growth peaked in summer and autumn. Observations indicate that peak root demand for carbohydrates occurs when fruit demands are also high. This infers competition between fruit and root growth, disagreeing with observations in other species. Carbohydrate partitioning between fruit and roots was studied in small kiwifruit plants using the tracer 14C. Simultaneous tracer import was observed into fruit and roots. When half the root system was cut off, root system import was reduced. The fruit imported a larger proportion of the available tracer, whilst there was no change in import into the remaining root half. Simultaneous carbohydrate import into fruit and roots demonstrated competition between these sinks. However, increased carbohydrate import into fruit suggests that the fruit has higher priority. The findings of this research suggest that the root system is a more competitive sink in kiwifruit vines than in some other fruit crops.
Trunk girdling and root pruning are used to improve kiwifruit vine productivity. The effects of these practices on vine physiology, and root growth and function were investigated. Girdling reduced photosynthesis, with reductions attributed to stomatal limitation and feedback inhibition. Repeat annual girdling reduced root biomass by approximately 59%. Root growth rates were not affected, however, girdled vines produced less root tips. This suggests that new root production is more of a carbon expense than root extension. Root pruning reduced whole-vine hydraulic conductance. As treatment severity increased, reduced photosynthesis was evident, attributed to reduced sink demand. Roots in other species have demonstrated rapid changes in hydraulic conductance in response to environmental stresses. Hydraulic conductance in intact roots of kiwifruit vines did not respond when 80% of root biomass was removed. However, sap flow increased to a rate approximately 50% higher than pre-treatment. Kiwifruit roots exhibited hydraulic redundancy, which may be a stress tolerance mechanism.

year: 2012

title: Development of an HPLC method to analyze four veterinary antibiotics in soils and aqueous media and validation through fate studies

authors: Srinivasan, Prakash

subjects: HPLC

abstract: A simple, yet robust analytical method was developed to detect and quantify three sulfonamides (SA), namely sulfamethoxazole (SMO), sulfachloropyridazine (SCP), and sulfamethazine (SM), and a macrolide tylosin (TT) in aqueous (calcium chloride and leachate solutions) and solid (agricultural soils) matrices using high performance liquid chromatography and ultra violet detection at 290 nm (TT) and 275 nm (SA) respectively. Chromatography was performed using a Phenomenex Onyx Monolithic C-18 column for TT and a C-18 Luna column for sulfonamides as single analytes eluted isocratically with a mobile phase consisting of acetonitrile: trifluoroacetic acid: tetrahydrofuran in the ratio 22.5:68:9.5 for TT, 40:55:5 for SMO, 32:63:5 for SCP and 31:64:5 for SM (v/v) at 1.0 mL min(-1) and an injection volume of 20 mu L. A gradient method to detect all three sulfonamides in a single run was also developed. The soil residue analysis consisted of extraction with dichloromethane and pre-concentration steps as the aqueous phase was measured directly. The limits of detection at an S/N (signal: noise) ratio of 3 were 20.0 mu g L-1 and 50 mu g L-1 for all sulfonamides and tylosin respectively. The average recoveries for all sulfonamides and tylosin in aqueous matrices ranged from 95 to 105% across the six concentrations investigated. Recoveries from the soils were slightly lower for sulfonamides and tylosin. The isocratic method was used to determine the sorption and degradation of sulfonamides in soils, while the gradient method was used to determine degradation kinetics and leachate concentrations in soils and aqueous systems.

text: Development of an HPLC method to analyze four veterinary antibiotics in soils and aqueous media and validation through fate studies A simple, yet robust analytical method was developed to detect and quantify three sulfonamides (SA), namely sulfamethoxazole (SMO), sulfachloropyridazine (SCP), and sulfamethazine (SM), and a macrolide tylosin (TT) in aqueous (calcium chloride and leachate solutions) and solid (agricultural soils) matrices using high performance liquid chromatography and ultra violet detection at 290 nm (TT) and 275 nm (SA) respectively. Chromatography was performed using a Phenomenex Onyx Monolithic C-18 column for TT and a C-18 Luna column for sulfonamides as single analytes eluted isocratically with a mobile phase consisting of acetonitrile: trifluoroacetic acid: tetrahydrofuran in the ratio 22.5:68:9.5 for TT, 40:55:5 for SMO, 32:63:5 for SCP and 31:64:5 for SM (v/v) at 1.0 mL min(-1) and an injection volume of 20 mu L. A gradient method to detect all three sulfonamides in a single run was also developed. The soil residue analysis consisted of extraction with dichloromethane and pre-concentration steps as the aqueous phase was measured directly. The limits of detection at an S/N (signal: noise) ratio of 3 were 20.0 mu g L-1 and 50 mu g L-1 for all sulfonamides and tylosin respectively. The average recoveries for all sulfonamides and tylosin in aqueous matrices ranged from 95 to 105% across the six concentrations investigated. Recoveries from the soils were slightly lower for sulfonamides and tylosin. The isocratic method was used to determine the sorption and degradation of sulfonamides in soils, while the gradient method was used to determine degradation kinetics and leachate concentrations in soils and aqueous systems.

year: 2012

title: Cultural justice and ethics: From within

authors: Garner, Kerin

subjects: Maori

abstract: Where I eventually got a lot of support, awhi, aroha, was from the PPTA when I became a member of Te Huarahi and they helped to see me through the tears and the confusion. It wasn’t because I was Maori, it was because I was a human being. I think the process I have gone through is a process of becoming human, and becoming real in thinking; yes, my experience is valid. I’m not just Maori, I’m Pakeha too. I want both of them, I am both of them. I don’t have to get up and speak fluent Maori right now. Perhaps it will come. I hope it does because I want it to, and I’m going to work on it. But I do feel that people like me, and there are many of us, are not marginal. We are bridges between cultures. This diversity has to be acknowledged, honoured and respected.

text: Cultural justice and ethics: From within Where I eventually got a lot of support, awhi, aroha, was from the PPTA when I became a member of Te Huarahi and they helped to see me through the tears and the confusion. It wasn’t because I was Maori, it was because I was a human being. I think the process I have gone through is a process of becoming human, and becoming real in thinking; yes, my experience is valid. I’m not just Maori, I’m Pakeha too. I want both of them, I am both of them. I don’t have to get up and speak fluent Maori right now. Perhaps it will come. I hope it does because I want it to, and I’m going to work on it. But I do feel that people like me, and there are many of us, are not marginal. We are bridges between cultures. This diversity has to be acknowledged, honoured and respected.

year: 1993