External tuber disorders: Malformed tubers
September 26, 2022
PotatoWorld editorial
Malformed tubers take many shapes. The deformed or misshapen tubers may be knobby, doll-like, have bottle necks like dumbbells and have a spiked rose end (pear shaped).
All these appearances are the result of secondary growth. Secondary growth symptoms appear on tubers when they were formed and grew under optimal temperature, moisture and nitrogen conditions for some time. When these conditions are interrupted by heat and drought that stops tuber growth and afterward growth resumes ‘secondary growth’ is referred to.
Lower dry matter concentration
The loss of quality due to secondary growth is not only caused by the removal of deformed tubers at sorting but also due to the lower dry matter concentration in both primary and secondary tubers. Moreover, the dry matter is distributed unevenly over the tuber (and between tubers) and so are the reducing sugars. In pointed tubers, this leads to visible brown ‘sugar ends’ when chips of such tubers are fried. The major effort by growers to avoid secondary growth, apart from growing less susceptible varieties, is assuring a regular supply of water. In the case of a heat wave, they pay special attention to irrigation to cool down the high temperatures of the soil. Single stemmed plants also lead to more defects than plants that usually consist of several stems, say four or five growing from relatively large and old seed tubers.
You may also be interested in:
The efficiency of overhead irrigation for potato crops
Irrigation with sprinklers, rain guns, center pivots or linear systems – as opposed to furrow and drip irrigation delivering water under the canopy – distributes water overhead, much like natural rainfall does.
The advantages of drip irrigation in potato cultivation
Of all irrigation practices, furrow irrigation loses most water through drainage and also loses more nitrogen through leaching than other irrigation practices. Drainage through deep percolation on the other hand is an advantage as it avoids accumulation of salts at the surface. Besides, erosion is considerable as the water flow to some extent always transports…
Potato Association of America to showcase industry advances during annual meeting
The annual meeting of the Potato Association of America (PAA) is scheduled to take place from July 23rd to 27th, 2023. PAA members, potato researchers and industry partners will gather in Charlottetown, the capital of Prince Edward Island. ‘We look forward to welcoming the PAA family to Prince Edward Island for the first time since…
Furrow irrigation in potato cultivation
Where there is not enough rainfall and evapotranspiration exceeds precipitation, the crop is irrigated. That is if there is surface water or underground water available at acceptable distance and depth from the field. What is more, the grower needs to have available the capital to invest in equipment. The irrigation technique requiring the least investment…