Growth and phosphorus, zinc, and manganese content of tomato, muskmelon, and honey locust at high root‐zone temperatures¹

Received for publication 10–20–95. Journal Paper no. J‐16551 of the Iowa Agriculture and Home Economics Station, Ames, Iowa. Project No. 3081 and 3229. This paper is in partial fulfillment for the requirements for a Ph.D. degree in Horticulture.

Abstract

Horticultural species vary in growth response to root‐zone temperature (RZT) that exceed 30°C, but little is known about the effects of RZT on nutrient absorption. We determined the amount of phosphorus (P), zinc (Zn), and manganese (Mn) in plants of tomato (Lycopersicon esculentum Mill. ‘Jet Star'), muskmelon (Cucumis melo L. ‘Gold Star'), and thornless honey locust (Gleditsia triacanthos L. var. inermis Willd.) grown in an Hoagland No. 1 nutrient solution that was held at 24°, 27°, 30°, 33°, and 36°C RZT. Tomato dry mass and P and Mn contents were highest at 27°C RZT, but tomato Zn content did not show a response to RZT. Muskmelon dry mass and P, Zn, and Mn contents, however, were highest at 36°C. Honey locust dry mass and P and Zn contents did not vary with RZT, but honey locust Mn content decreased linearly with increasing RZT. Growth and P, Zn, and Mn absorption by muskmelon were increased by continuous exposure to RZT > 30°C, whereas honey locust growth and P, Zn, and Mn acquisition were not changed by exposure to RZT > 30°C. Growth and P, Zn, and Mn absorption by tomato, however, were decreased by continuous exposure to RZT > 30°C.

Notes

Received for publication 10–20–95. Journal Paper no. J‐16551 of the Iowa Agriculture and Home Economics Station, Ames, Iowa. Project No. 3081 and 3229. This paper is in partial fulfillment for the requirements for a Ph.D. degree in Horticulture.

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