title: Aspects of the root ecology of Neotyphodium endophytes in Lolium perenne

authors: Popay, Alison J.

abstract: Three different strains of the biotrophic endosymbiont, Neotyphodium, in perennial ryegrass were compared with endophyte-free ryegrass (Nil) for their effects on root herbivory, soil biota, root growth, root morphology and alkaloid and nutrient content in pot trials. 

Ryegrass infected with the endophyte strain, AR37, which produces janthitrem alkaloids, was toxic to a root aphid, Aploneura lentisci. Relative to Nil plants, ryegrass with Wild-type endophyte (producing the alkaloids peramine, ergovaline and lolitrem B) showed occasional resistance to A. lentisci whereas ryegrass with AR1 (producing peramine only) was highly susceptible. A high variability in root aphid populations among individual AR1 plants was related to plant genotype or a plant genotype/endophyte interaction. Differential effects of endophyte on A. lentisci were maintained under nutrient stress. Neither AR37 nor AR22 (a strain similar to AR1) in ryegrass affected feeding or survival of root-feeding larvae of the scarab Costelytra zealandica. 

Endophyte infection had no discernible adverse effects on populations of Collembola, oribatid mites or dorylaimid nematodes. Higher root aphid populations were associated with higher populations of Collembola and lower populations of nematodes. Rate of mycorrhizal colonisation of ryegrass infected with AR37 and Wild-type was slower than in AR1 and Nil but then proceeded rapidly to the extent that they became more heavily infected than AR1. After 2 years, infection of roots of AR1-infected plants was less than on AR37, Wild-type and Nil plants.

Alkaloid content of roots was very low relative to that of leaf sheaths. Two janthitrem fractions were consistently found in roots of AR37 plants and may be the cause of toxicity to root aphid. Ergovaline and lolitrem B were only found in roots under certain conditions and adverse effects of Wild-type infection on A. lentisci could not be attributed conclusively to the presence of either alkaloid.

Manipulation of herbivory by insecticide showed that root and foliar growth of AR1 and Nil plants were reduced by A. lentisci and also by an unidentified pseudococcid species infesting tillers. Root/shoot ratios were occasionally reduced in the presence of both species and in the presence of A. lentisci alone suggesting plant allocation to foliar growth in response to damage by these insects.

Not all effects of endophyte infection were mediated by herbivory. AR1-infected ryegrass had a higher specific root length than Nil plants with AR37 and Wild-type intermediate between these. Insecticide treatment increased specific root length in all plants but relative differences between endophyte treatments remained the same. AR37 differed from other endophyte treatments in having a lower investment in root growth and increasing root nitrogen concentrations during summer followed by a relatively larger investment in root growth in autumn and early winter. Protection from herbivory meant that actual root biomass of AR37 plants was not less than in other treatments. 

Endophyte-infected plants had higher concentrations of potassium and phosphorus than Nil plants in roots but not in leaf blades. Nitrogen concentrations in roots were inversely related to root biomass resulting in AR1-infected plants having the highest concentrations of nitrogen due to the adverse effects of A. lentisci on root growth. The higher nutrient content of AR1-infected ryegrass compared with Nil may increase its susceptibility to A. lentisci.

It is concluded that Neotyphodium infection has multiple but highly strain-specific effects on root ecology of perennial rye grass.

text: Aspects of the root ecology of Neotyphodium endophytes in Lolium perenne Three different strains of the biotrophic endosymbiont, Neotyphodium, in perennial ryegrass were compared with endophyte-free ryegrass (Nil) for their effects on root herbivory, soil biota, root growth, root morphology and alkaloid and nutrient content in pot trials. 

Ryegrass infected with the endophyte strain, AR37, which produces janthitrem alkaloids, was toxic to a root aphid, Aploneura lentisci. Relative to Nil plants, ryegrass with Wild-type endophyte (producing the alkaloids peramine, ergovaline and lolitrem B) showed occasional resistance to A. lentisci whereas ryegrass with AR1 (producing peramine only) was highly susceptible. A high variability in root aphid populations among individual AR1 plants was related to plant genotype or a plant genotype/endophyte interaction. Differential effects of endophyte on A. lentisci were maintained under nutrient stress. Neither AR37 nor AR22 (a strain similar to AR1) in ryegrass affected feeding or survival of root-feeding larvae of the scarab Costelytra zealandica. 

Endophyte infection had no discernible adverse effects on populations of Collembola, oribatid mites or dorylaimid nematodes. Higher root aphid populations were associated with higher populations of Collembola and lower populations of nematodes. Rate of mycorrhizal colonisation of ryegrass infected with AR37 and Wild-type was slower than in AR1 and Nil but then proceeded rapidly to the extent that they became more heavily infected than AR1. After 2 years, infection of roots of AR1-infected plants was less than on AR37, Wild-type and Nil plants.

Alkaloid content of roots was very low relative to that of leaf sheaths. Two janthitrem fractions were consistently found in roots of AR37 plants and may be the cause of toxicity to root aphid. Ergovaline and lolitrem B were only found in roots under certain conditions and adverse effects of Wild-type infection on A. lentisci could not be attributed conclusively to the presence of either alkaloid.

Manipulation of herbivory by insecticide showed that root and foliar growth of AR1 and Nil plants were reduced by A. lentisci and also by an unidentified pseudococcid species infesting tillers. Root/shoot ratios were occasionally reduced in the presence of both species and in the presence of A. lentisci alone suggesting plant allocation to foliar growth in response to damage by these insects.

Not all effects of endophyte infection were mediated by herbivory. AR1-infected ryegrass had a higher specific root length than Nil plants with AR37 and Wild-type intermediate between these. Insecticide treatment increased specific root length in all plants but relative differences between endophyte treatments remained the same. AR37 differed from other endophyte treatments in having a lower investment in root growth and increasing root nitrogen concentrations during summer followed by a relatively larger investment in root growth in autumn and early winter. Protection from herbivory meant that actual root biomass of AR37 plants was not less than in other treatments. 

Endophyte-infected plants had higher concentrations of potassium and phosphorus than Nil plants in roots but not in leaf blades. Nitrogen concentrations in roots were inversely related to root biomass resulting in AR1-infected plants having the highest concentrations of nitrogen due to the adverse effects of A. lentisci on root growth. The higher nutrient content of AR1-infected ryegrass compared with Nil may increase its susceptibility to A. lentisci.

It is concluded that Neotyphodium infection has multiple but highly strain-specific effects on root ecology of perennial rye grass.

year: 2004

title: Cow breed, stocking rate, and calving date affect the profitability of pasture-based dairy farms

authors: Spaans, Olivia Katherine

abstract: Data from two multi-year experiments undertaken at the DairyNZ research farm, No 2. Dairy were collated and analysed. The effects of:
1)	 Breed (Jersey or Holstein-Friesian; JER, HF) at optimum or high comparative stocking rates (CSR; 80 or 100 kg body weight (BW)/t dry matter (DM) of feed available; CSR80 and CSR100, respectively); and 
2)	Changing the mean calving date (January, April, July, or October; JAN, APR, JUL, OCT) 
on biophysical measurements (i.e., milk production, pasture growth) and farm profitability were determined. 
Changing these strategic management variables affected the amount of pasture grown and consumed. For example, there was an interaction between breed and CSR in many of the measured pasture and milk production variables in experiment one; whilst, in experiment two, changes in the month of calving affected pasture dry matter intake (DMI) in early-mid and mid-late lactation, and annual milk production. Annual pasture production was greatly reduced at CSR100 on the HF farmlet, but not on the JER farmlet. Month of calving affected pasture DMI during early-mid lactation and mid-late lactation. 
A breed x CSR interaction reduced milk production per cow at CSR100, an effect that was greater in the HF breed than in the JER. Month of calving affected milk production per cow with the JUL herd producing the highest yield, compared with the JAN, APR and OCT herds.
Other breed x CSR interactions were also detected: JER cows had the lowest mean days in milk (DIM) to first heat at both CSR80 and 100; furthermore, there were negative effects of an increase in CSR from 80 to 100 kg body weight/t DM feed in the HF breed on DIM to first heat. Total metabolisable energy (ME) requirements per cow was affected by a breed x CSR interaction. At CSR80, the HF used more ME per cow than the JER, whilst at CSR100, both breeds used less total ME per cow than at CSR80, but the HF again used more than the JER.
From a profitability perspective, HF cows had a greater operating profit per hectare than JER at CSR80; however, JER cows were more profitable at CSR100. The JUL herd had the most profitable farm system, in both the base economic model and stochastic model. Results of the stochastic modelling with no premium included in the milk payment (NZ$/kg fat and protein) variable revealed the operating profit per hectare was greatest for the JUL herd, compared with the JAN, APR, and OCT herds. Inclusion of a premium for milk supplied during 16 May to 15 July in the milk payment (NZ$/ kg fat and protein) variable as well as a downward adjustment in milk price for JUL calving cows because of the high milk production peak in spring did not overcome this difference in profitability. Therefore, the JUL calving scenario was most profitable. The APR seasonal calving strategy resulted in a 10% reduction in operating profit per hectare, compared with the JUL herd, while the JAN and OCT strategy had the lowest operating profit per hectare.

text: Cow breed, stocking rate, and calving date affect the profitability of pasture-based dairy farms Data from two multi-year experiments undertaken at the DairyNZ research farm, No 2. Dairy were collated and analysed. The effects of:
1)	 Breed (Jersey or Holstein-Friesian; JER, HF) at optimum or high comparative stocking rates (CSR; 80 or 100 kg body weight (BW)/t dry matter (DM) of feed available; CSR80 and CSR100, respectively); and 
2)	Changing the mean calving date (January, April, July, or October; JAN, APR, JUL, OCT) 
on biophysical measurements (i.e., milk production, pasture growth) and farm profitability were determined. 
Changing these strategic management variables affected the amount of pasture grown and consumed. For example, there was an interaction between breed and CSR in many of the measured pasture and milk production variables in experiment one; whilst, in experiment two, changes in the month of calving affected pasture dry matter intake (DMI) in early-mid and mid-late lactation, and annual milk production. Annual pasture production was greatly reduced at CSR100 on the HF farmlet, but not on the JER farmlet. Month of calving affected pasture DMI during early-mid lactation and mid-late lactation. 
A breed x CSR interaction reduced milk production per cow at CSR100, an effect that was greater in the HF breed than in the JER. Month of calving affected milk production per cow with the JUL herd producing the highest yield, compared with the JAN, APR and OCT herds.
Other breed x CSR interactions were also detected: JER cows had the lowest mean days in milk (DIM) to first heat at both CSR80 and 100; furthermore, there were negative effects of an increase in CSR from 80 to 100 kg body weight/t DM feed in the HF breed on DIM to first heat. Total metabolisable energy (ME) requirements per cow was affected by a breed x CSR interaction. At CSR80, the HF used more ME per cow than the JER, whilst at CSR100, both breeds used less total ME per cow than at CSR80, but the HF again used more than the JER.
From a profitability perspective, HF cows had a greater operating profit per hectare than JER at CSR80; however, JER cows were more profitable at CSR100. The JUL herd had the most profitable farm system, in both the base economic model and stochastic model. Results of the stochastic modelling with no premium included in the milk payment (NZ$/kg fat and protein) variable revealed the operating profit per hectare was greatest for the JUL herd, compared with the JAN, APR, and OCT herds. Inclusion of a premium for milk supplied during 16 May to 15 July in the milk payment (NZ$/ kg fat and protein) variable as well as a downward adjustment in milk price for JUL calving cows because of the high milk production peak in spring did not overcome this difference in profitability. Therefore, the JUL calving scenario was most profitable. The APR seasonal calving strategy resulted in a 10% reduction in operating profit per hectare, compared with the JUL herd, while the JAN and OCT strategy had the lowest operating profit per hectare.

year: 2018

title: Te Hokinga ki te Pā Harakeke

authors: Hohepa, Margie Kahukura

abstract: 'Tiakina Te Pā Harakeke' investigates the collective values that nourish and enhances the well-being of tamariki Māori as taonga within our whānau, hapū and iwi. lt explores ways in which Māori values and tikanga are harnessed in contemporary whānau contexts to provide safe, vibrant and enriched childrearing. parenting and child-focussed strategies.

text: Te Hokinga ki te Pā Harakeke 'Tiakina Te Pā Harakeke' investigates the collective values that nourish and enhances the well-being of tamariki Māori as taonga within our whānau, hapū and iwi. lt explores ways in which Māori values and tikanga are harnessed in contemporary whānau contexts to provide safe, vibrant and enriched childrearing. parenting and child-focussed strategies.

year: 2014