Effects of vertical distribution of soil inorganic nitrogen on root growth and subsequent nitrogen uptake by field vegetable crops

Information is needed about root growth and N uptake of crops under different soil conditions to increase nitrogen use efficiency in horticultural production. The purpose of this study was to investigate if differences in vertical distribution of soil nitrogen (Ninorg) affected root growth and N uptake of a variety of horticultural crops. Two field experiments were performed each over 2 years with shallow or deep placement of soil Ninorg obtained by management of cover crops. Vegetable crops of leek, potato, Chinese cabbage, beetroot, summer squash and white cabbage reached root depths of 0.5, 0.7, 1.3, 1.9, 1.9 and more than 2.4 m, respectively, at harvest, and showed rates of root depth penetration from 0.2 to 1.5 mm day)1 C)1. Shallow placement of soil Ninorg resulted in greater N uptake in the shallow-rooted leek and potato. Deep placement of soil Ninorg resulted in greater rates of root depth penetration in the deep-rooted Chinese cabbage, summer squash and white cabbage, which increased their depth by 0.2–0.4 m. The root frequency was decreased in shallow soil layers (white cabbage) and increased in deep soil layers (Chinese cabbage, summer squash and white cabbage). The influence of vertical distribution of soil Ninorg on root distribution and capacity for depletion of soil Ninorg was much less than the effect of inherent differences between species. Thus, knowledge about differences in root growth between species should be used when designing crop rotations with high N use efficiency

Agronomic and physiological responses of potato subjected to soil compaction and/or drying

Compact and dry soils impede root growth and restrict plant water availability, respectively, potentially causing leaf water deficit. Although both stresses likely co-occur in the field and limit yield, little is known about their combined impact on plant growth and physiology over a whole season, especially in a tuberous crop like potato. Field-grown potato (Solanum tuberosum L. var. 'Maris Piper') was exposed to factorial combination of deficit irrigation (watering when soil moisture deficit reached 60 vs. 25 mm) and soil compaction (compacted with heavy machinery vs. uncompacted), with plant growth and leaf physiology measured weekly. Shoot growth was restricted by adverse soil conditions, while leaf water status, photosynthesis rates and leaf abscisic acid (ABA) levels did not vary significantly between treatments. Across all treatments, final yield was linearly correlated (R2 = 0.71) to mid-season shoot biomass. Compared to well-watered plants growing in loose soil, soil compaction, deficit irrigation and their combination decreased final tuber yield similarly, by 23%–34%. Surprisingly, tuber size distribution was more dependent on irrigation management than on soil strength. Plants exposed to deficit irrigation produced more, smaller potatoes than their respective control. Thus, low soil water availability and/or compact soil caused these field-grown potatoes to restrict shoot growth rather than limit leaf gas exchange. Further research is needed to understand the role of hormonal signalling in regulating tuber growth when plants are exposed to compact and dry soils. © 2021 The Authors. Annals of Applied Biology published by John Wiley & Sons Ltd on behalf of Association of Applied Biologists

Time-lapse geophysical assessment of agricultural practices on soil moisture dynamics

Geophysical surveys are now commonly used in agriculture for mapping applications. High-throughput collection of geophysical properties such as electrical conductivity (inverse of resistivity), can be used as a proxy for soil properties of interest (e.g. moisture, texture, salinity). Most applications only rely on a single geophysical survey at a given time. However, time-lapse geophysical surveys have greater capabilities to characterize the dynamics of the system, which is the focus of this work. Assessing the impact of agricultural practices through the growth season can reveal important information for the crop production. In this work, we demonstrate the use of time-lapse electrical resistivity tomography (ERT) and electromagnetic induction (EMI) surveys through a series of three case studies illustrating common agricultural practices (cover crops, compaction with irrigation, tillage with nitrogen fertilization). In the first case study, time-lapse EMI reveals the initial effect of cover crops on soil drying and the absence of effect on the subsequent main crop. In the second case study, compaction, leading to a shallower drying depth for potatoes was imaged by time-lapse ERT. In the third case study, larger change in electrical conductivity over time were observed in conventional tillage compared to direct drill using time-lapse EMI. In addition, different nitrogen application rates had significant effect on the yield and leaf area index but only ephemeral effects on the dynamics of electrical conductivity mainly after the first application. Overall, time-lapse geophysical surveys show great potential for monitoring the impact of different agricultural practices that can influence crop yield

Morphophysiology of potato (Solanum tuberosum) in response to drought stress: paving the way forward

The cultivated potato (Solanum tuberosum L.) is currently the third most important food crop in the world and is becoming increasingly important to the local economies of developing countries. Climate change threatens to drastically reduce potato yields in areas of the world where the growing season is predicted to become hotter and drier. Modern potato is well known as an extremely drought susceptible crop, which has primarily been attributed to its shallow root system. This review addresses this decades old consensus, and highlights other, less well understood, morphophysiological features of potato which likely contribute to drought susceptibility. This review explores the effects of drought on these traits and goes on to discuss phenotypes which may be associated with drought tolerance in potato. Small canopies which increase harvest index and decrease evapotranspiration, open stem-type canopies which increase light penetration, and shallow but densely rooted cultivars, which increase water uptake, have all been associated with drought tolerance in the past, but have largely been ignored. While individual studies on a limited number of cultivars may have examined these phenotypes, they are typically overlooked due to the consensus that root depth is the only significant cause of drought susceptibility in potato. We review this work, particularly with respect to potato morphology, in the context of a changing climate, and highlight the gaps in our understanding of drought tolerance in potato that such work implies

Growth and water use of the potato variety Record on contrasting sites

SIGLEAvailable from British Library Document Supply Centre- DSC:D60825 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Climate change and land suitability for potato production in England and Wales: impacts and adaptation

The viability of commercial potato production is influenced by spatial and temporal variability in soils and agroclimate, and the availability of water resources where supplemental irrigation is required. Soil characteristics and agroclimatic conditions greatly influence the cultivar choice, agronomic husbandry practices and the economics of production. Using the latest (UKCP09) scenarios of climate change for the UK, this paper describes a methodology using pedo-climatic functions and a GIS to model and map current and future land suitability for potato production in England and Wales. The outputs identify regions where rainfed production is likely to become limiting and where future irrigated production would be constrained due to shortages in water availability. The results suggest that by the 2050s, the area of land that is currently well or moderately suited for rainfed production would decline by 74 and 95% under the "most likely" climate projections for the low and high emissions scenario respectively, owing to increased droughtiness. In many areas, rainfed production would become increasingly risky. However, with supplemental irrigation, around 85% of the total arable land in central and eastern England would remain suitable for production, although most of this is in catchments where water resources are already over-licensed and/or over-abstracted; the expansion of irrigated cropping is thus likely to be constrained by water availability. The increase in volumetric water demand due to the switch from rainfed to irrigated potato cropping is likely to be much greater than the incremental increase in water demand solely on irrigated potatoes. The implications of climate change on the potato industry, the adaptation options and responses available, and the uncertainty associated with the land suitability projections, are discussed

Growth and water use of the potato variety Record on contrasting sites

A series of experiments was conducted at three contrasting sites (Cambridge University Farm, Gleadthorpe and Terrington Experimental Husbandry Farms) in four years (1985-88) to examine the effect of site, season and husbandry on growth and water use of the potato variety Record. Crisp processing quality was assessed at harvest and after periods of storage. Confounding of site and season with husbandry was avoided by maintaining similar husbandry in one experiment common to all sites and seasons. In 1989 at Cambridge, crops were grown in polythene tunnels to determine the effect of controlled water input on the number of tubers and efficiency of water use. Growth, development and yield of crops with similar husbandry generally did not differ between sites and seasons. Effects of husbandry (e.g. date of planting and date of harvest) at each site in all years were generally large compared with site and season effects. However, physiological age of seed tubers and irrigation regime had very little effect. Intercepted radiation was converted to tuber dry matter with greater efficiency in 1987 at Gleadthorpe than at the other two sites. In 1987, there was no effect of site on water use (evapotranspiration) efficiency with respect to tuber dry matter production, but later plantings used water more efficiently than early plantings. In 1988, the early planting at Gleadthorpe used water more efficiently than a similar date of planting at Cambridge. Excluding rainfall and withholding irrigation increased water use efficiency in 1989, and yield was lower from a crop kept close to field capacity than one which received the same amount of water over the season, but at less frequent intervals. Restricting crop water availability to soil reserves reduced the number of tubers greater than 10mm, but irrigation regime had no consistent effect on the number of tubers initiated or retained where rainfall input could not be controlled. Water uptake was related to depth and density of rooting, and date of planting and irrigation regime had considerable effects on root distribution. There were interaction effects between site and season on crisp fry colour. Delayed harvest resulted in darker crisps, but fry colour after long-term storage (36-40 weeks) could not be predicted from the colour at harvest. No significant correlation could be established between individual, or total, tuber sugar concentration and crisp colour.Digitisation of this thesis was sponsored by Arcadia Fund, a charitable fund of Lisbet Rausing and Peter Baldwin