PW-ACTUA Potato Handbook well received During the recent Potato Demonstration Day in Westmaas, Potato World BV presented the Potato Handbook by the famous potato professor Anton Haverkort. Although the potato specialist retired two years ago, he certainly did not sit back quietly watching the grass grow. He put pen to paper and the result was presented during the wellattended book presentation. ‘Two thick manuals full of knowledge about the potato, one in Dutch and one in English. They’ve turned out to be weighty books of no less than 1.6 kilograms with 600 pages of accessible explanations, photographs, and diagrams. In short, a book from which every player in the potato chain can learn a lot to improve his business operations’, publisher Jaap Delleman proudly announces about the new Potato Handbook. Crop of the future European Parliamentarian Annie Schreijer-Pierik was very pleased to receive a first copy of the reference work Potato handbook Crop of the future The presentation by Potato World BV of the Potato Handbook during the recent Potato Demonstration Day in Westmaas. Left to right: Anton Haverkort (author), Annie Schreijer-Pierik (MEP), Dick Hylkema (NAO), Jaap Delleman (publisher) en Ernst van den Ende (WUR). Anton J. Haverkort from the author himself. She expressed her admiration both on the day as well as via Twitter. ‘Potatoes are the crop of the future: worldwide demand is growing. An honour to receive the first copy of the Potato Handbook by Anton Haverkort’, writes the politician on Twitter. Indispensable reference work The complete reference book describes the potato from molecular level to production systems and from subsistance farming to advanced agriculture. In short, a reference work that is indispensable for anyone who is active or interested in the potato. The book starts with the people who eat potatoes, earn money with them and set up organisations about them. The book then deals with parts of the plant itself, its growth, the use of resources and how it defends itself against pests and diseases. The genetics and physiology of the planting stock play a central role, as do soil, weather and climate change. The book ends with the high and low tech aspects of cultivation and storage. The cover illustration prominently shows the formula: O = S x DSB x OI/DSG. It is the formula for calculating the fresh tuber yield (O). This is higher as more solar radiation (S) is absorbed, which is converted 4. Environment Daylength versus latitude 18 16 14 12 10 8 6 1 2 3 4 5 6 7 8 9 10 11 12 50° 1=January.......................................... 12=December Month 0 degrees latitude 25 °N 50 °N 25 °S 50 °S More remote from the equator the days lengthen in summer and shorten in winter. The photoperiod is 12 h throughout the year at the equatorial highlands, around 11 h in subtropical winters and Mediterranean spring and autumn. Photoperiods move up to 17 h at 50–60 degrees latitudes North and South during summer. The photoperiod in greenhouses is not lengthened for production purposes but for breeding purposes; it is done to postpone tuber formation and enhance flowering 15–16 h daylength at 40 to 50 degrees latitude. The same ones only have a 90–100-day cycle when grown over short days in subtropical winters in the lowlands, or in tropical highlands throughout the year. On longer days, the crop initiates its tubers later and matures later. There are, however, large differences between varieties when they are planted in a region with another daylength. Variety Désirée for instance is quite daylength insensitive and performs well in photoperiods of 11 h in subtropical winters as well as under 20 h daylength in Lapland. Variety Bintje, however, is best adapted to long days. When planted in a Mediterranean environment with 11 h daylight at emergence, the variety initiates its tubers immediately after emergence, tubers then compete at an early stage with 340 Main season 35° Latitude Autumn season 20° 0° fluctuating amount of instable ozone (O3 ) around an average of 50 parts per billion (ppb). All four gases (N2 , O2, CO2 and O3) directly or indirectly The daylength mid-season is around 16 h at 50 °N and S and around 13 h at 35 °N and S in the spring season and around 11 h in the autumn season. This is similar to the daylength at 20 °N and S during the winter crop. Around the equator the daylength is 12 h throughout the year. The length of the season from planting till crop maturity at harvest is correlated to the photoperiod and varies from 180 days at the 16 h photoperiod and 90 days at the 11 h photoperiod the foliage that dies off well before the end of the growing season. This makes that variety unsuitable for short day cropping seasons. In tropical highlands where potatoes can be grown throughout the year, growers in the Andean highland grow late maturing 180-day cycle varieties of the species Solanum andigenum. In most other tropical areas on the other continents, farmers cultivate 90–110-day cycle varieties of Solanum tuberosum. Atmospheric gases The atmosphere consists for 78% of nitrogen (N2 ppm, parts per million) of carbon dioxide (CO2 Apart from these major gases, there are traces of neon, helium and methane. There is also a ), 21% oxygen (O2), 0.9% argon (Ar) and 0,04% (400 ). The three atmospheric gases directly (O2 indirectly after conversion (N2 and CO2 ) or ) are needed for crop growth interact with crop growth. Nitrogen in the air is bound by bacteria or synthetically in factories and becomes available to plants as nitrate or ammonia. Oxygen is released in photosynthesis [6 CO2 + 6 H2O → C6 H12O6 H12O6 + 6 O2 + 6 O2 ]. This gas is absorbed in respiration. Carbon dioxide is absorbed in photosynthesis and released in respiration: [C6 → 6 CO2 + 6 H2 Only ozone is a deleterious gas and causes O]. Growth limiting factors Nutrients Nitrogen (N2 ) Oxygen (O2 ) Atmospheric gas composition Nitrogen (78) Argon (0.9) Oxigen (21) Carbondioxide (0.04) Carbon Dioxide (CO2 ) The yield-defining factors solar radiation, daylength, temperature and carbon dioxide concentration are altered in controlled conditions. Greenhouses change all factors and nurseries change radiation and temperature at relatively high costs. In plant breeding and the production of high-priced vegetables and ornamentals, creating such conditions pays off. Large-scale staple food production takes place in the open and there such factors are not affected by the grower other than by screens and mulch. Yield-affecting measures that arable farmers apply in fields are the application to crops of nutrients and water. The primary or macro-elements taken up by the crop are nitrogen, phosphorus and potassium supplied by the hundreds of kg per hectare. In terms of quantity, they are followed by the secondary or meso-elements that are taken up to a lesser degree and have a lower concentration in the harvested tuber. These elements are supplied 341 220 Latitude and photoperiod dependence of the length of the growing season more efficiently into dry matter (DSB) and more of all the dry matter formed ends up in the tubers (OI, Harvest Index) and the dry matter content (DSG) is lower. The tuber yield depends on the amount of radiation absorbed, how effectively it is converted into dry matter and how much of that dry matter ends up in the tuber and of the water content of the tuber. ● 4. Environment symptoms in the leaves. Ozone enters through the stomates, causes leakage of cell membranes, interferes with photosynthesis and decreases plant growth. Plants defend themselves with anti-oxidants such as ascorbic acid (Vitamin C). 170 120 70 20 Ozone formation caused by high incidence of solar radiation and industrial exhaust in summer lead to high near surface concentrations of damaging ozone The concentrations of nitrogen and oxygen do not limit plant growth, but that of carbon dioxide does. The higher its concentration the higher the photosynthetic rate. The current CO2 concentration is above 400 ppm and increasing with 2 ppm per year because of burning by man of the fossil carbon sources coal, oil and gas. In addition, large quantities are released by thawing of the permafrost. A second essential property of carbon dioxide is its functioning as a greenhouse gas. Part of the incoming solar radiation is absorbed by CO2 and most of it is emitted again. The difference in energy heats the atmosphere. Atmospheric water vapor (H2 O) is the major gas responsible for the greenhouse effect of the atmosphere followed by CO2 ozone (O3 ) and nitrous oxide (N2 , methane (CH4 O). ) Potato World 2018 • number 4 11 Daylength (h) Length of the growing season (days) Pagina 10

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