Pastoral agriculture, a significant driver of New Zealand’s economy, based on an introduced grassland ecology and technological advances

The New Zealand economy is export-driven and heavily reliant on the productivity of the pastoral sector. The transformation of native forest and tussock grassland ecologies to temperate grasslands occurred rapidly with the arrival of Europeans. However, this transplanted ecology required the development and use of plant, microbial, animal and management technologies for successful grassland farming. These have enabled New Zealand pastoral agriculture to compete effectively in international markets, without subsidies. The extensive list of plant-based and associated microbial-based adaptations, and the management strategies that have enabled the development of highly productive grasslands are described and reviewed. Credible science is required to inform the debate on the environmental impacts of pasture production to avoid misinformation proliferating. This needs transparent and objective integrity from the science community using funding that seeks no defined or preconceived outcomes. Critically, much of the success of New Zealand pastoral farming has been due to the willingness and ability of farmers to use, adapt, adopt and integrate new ideas and technologies into their farming systems. Historic, current and future challenges, and threats that impact on the productivity and sustainability of pastoral agriculture are described and the means to achieve further technology development to manage these is discussed

Tradeoff between Biomass and Flavonoid Accumulation in White Clover Reflects Contrasting Plant Strategies

An outdoor study was conducted to examine relationships between plant productivity and stress-protective phenolic plant metabolites. Twenty-two populations of the pasture legume white clover were grown for 4½ months during spring and summer in Palmerston North, New Zealand. The major phenolic compounds identified and quantified by HPLC analysis were glycosides of the flavonoids quercetin and kaempferol. Multivariate analysis revealed a trade-off between flavonoid accumulation and plant productivity attributes. White clover populations with high biomass production, large leaves and thick tap roots showed low levels of quercetin glycoside accumulation and low quercetin:kaempferol ratios, while the opposite was true for less productive populations. The latter included stress-resistant ecotypes from Turkey and China, and the analysis also identified highly significant positive relationships of quercetin glycoside accumulation with plant morphology (root:shoot ratio). Importantly, a high degree of genetic variation was detected for most of the measured traits. These findings suggest merit for considering flavonoids such as quercetin as potential selection criteria in the genetic improvement of white clover and other crops

Response of rice cultivars to phosphorus supply on an oxisol.

Genotypic differences in absorption or utilization of P might be exploited to improve efficiency of fertilizer use or to obtain higher productivity on P-deficient soils. The objective of this study was to evaluate responses by 75 genotypes of upland rice (Oryza sativa L.) to two soil P levels in two field experiments. In the first experiment, soil P levels (Mehlich 1) were 1.5 mg kg-1 and 5 mg kg-1, and in the second experiment, 3 mg kg-1 and 4.7 mg kg-1 of soil, respectively. Rice cultivars differed significantly in shoot dry matter production at flowering, grain yield, and plant P status. Based on a grain yield efficiency index, cultivars were classified as P-efficient or P-inefficient. Shoot dry matter was more sensitive to P-deficiency but was not related to grain yield. Phosphorus use efficiency was higher under the low P treatment. Phosphorus uptake was significantly correlated with dry matter, P concentration and P-efficiency ratio. Results of this study indicate that genetic differences in P-use efficiency exist among upland rice cultivars and may be exploited in breeding programs

Reductionist science in agriculture and horticulture

Science ensures that explanations and predictions about the biological and physical worlds are verifiable, while also providing an approach that enables improved understanding to develop and be permanently recorded. There are several terms in common usage that describe the approaches used in scientific research, but at the extremes, words such as ‘reductionism’ and ‘holism’ are now frequently encountered. While singular reductionism can result in key relationships and linkages being missed, holism appears to ignore the need to identify how confounding factors can affect the quality of understanding derived from complex systems. Here we suggest that science is not a simple dichotomy of reductionism versus holism. Instead, it comprises a more fluid and complex mission. However, within multidisciplinary agricultural and horticultural science one regularly finds words like ‘systems’, ‘integration’, and ‘unifying’. Reductionist science is certainly part of the pursuit of holistic solutions to problems, not least in transdisciplinary research

Severe insect pest impacts on New Zealand pasture: The plight of an ecological outlier

New Zealand’s intensive pastures, comprised almost entirely introduced Lolium L. and Trifolium L. species, are arguably the most productive grazing lands in the world. However, these areas are vulnerable to destructive invasive pest species. Of these, three of the most damaging pests are weevils (Coleoptera: Curculionidae) that have relatively recently been controlled by three different introduced parasitoids, all belonging to the genus Microctonus Wesmael (Hymenoptera: Braconidae). Arguably that these introduced parasitoids have been highly effective is probably because they, like many of the exotic pest species, have benefited from enemy release. Parasitism has been so intense that, very unusually, one of the weevils has now evolved resistance to its parthenogenetic parasitoid. This review argues that New Zealand’s high exotic pasture pest burden is attributable to a lack of pasture plant and natural enemy diversity that presents little biotic resistance to invasive species. There is a native natural enemy fauna in New Zealand that has evolved over millions of years of geographical isolation. However, these species remain in their indigenous ecosystems and, therefore, play a minimal role in creating biotic resistance in the country’s exotic ecosystems. For clear ecological reasons relating to the nature of New Zealand pastures, importation biological control can work extremely well. Conversely, conservation biological control is less likely to be effective than elsewhere

Severe Insect Pest Impacts on New Zealand Pasture: The Plight of an Ecological Outlier

© The Author(s) 2020. New Zealand’s intensive pastures, comprised almost entirely introduced Lolium L. and Trifolium L. species, are arguably the most productive grazing-lands in the world. However, these areas are vulnerable to destructive invasive pest species. Of these, three of the most damaging pests are weevils (Coleoptera: Curculionidae) that have relatively recently been controlled by three different introduced parasitoids, all belonging to the genus Microctonus Wesmael (Hymenoptera: Braconidae). Arguably that these introduced parasitoids have been highly effective is probably because they, like many of the exotic pest species, have benefited from enemy release. Parasitism has been so intense that, very unusually, one of the weevils has now evolved resistance to its parthenogenetic parasitoid.This review argues that New Zealand’s high exotic pasture pest burden is attributable to a lack of pasture plant and natural enemy diversity that presents little biotic resistance to invasive species.There is a native natural enemy fauna in New Zealand that has evolved over millions of years of geographical isolation. However, these species remain in their indigenous ecosystems and, therefore, play a minimal role in creating biotic resistance in the country’s exotic ecosystems. For clear ecological reasons relating to the nature of New Zealand pastures, importation biological control can work extremely well. Conversely, conservation biological control is less likely to be effective than elsewhere