Effect of soil temperature on direction of corn root growth

Abstract

More precise effects of soil t e m p e r a t u r e on t h e direction of corn root g r o w t h were d e t e r m i n e d b y growing seedlings in soil for s h o r t periods in g r o w t h c a b i n e t s controlled to give a range of soil t e m p e r a t u r e conditions.The angle of g r o w t h (relative to t h e horizontal} was f o u n d to be m i n i m u m (10 °) at c o n s t a n t 17°C. A b o v e or below this t e m p e r a t u r e (I0-30°C), a more vertical direction occurred. Cyclic t e m p e r a t u r e s also influenced direction, w i t h t h e m a x i m u m of t h e cycle a p p a r e n t l y d e t e r m i n i n g the angle. The duration of t h e m a x i m u m t e m p e r a t u r e period in a cycle necessary to initiate a direction effect was n o t d e t e r m i n e d , however.The significance of these findings in t h e field is t h a t modifications of soil t e m p e r a t u r e s b y mulches, etc. p r o b a b l y influence t h e d i s t r i b u t i o n of roots in t h e rooting zone of soils. This in t u r n m e a n s t h a t p l a n t b e h a v i o u r such as moisture a n d n u t r i e n t u p t a k e can be b e t t e r explained or m a n a g e d for maxim u m performance. * Former graduate student. Present address, Ministry of the Environment,

Genetic variation in the gravitropic response of maize roots to low temperatures

“…On the contrary, the crown roots grew in a slightly more vertical direction. Similar effects were observed by Onderdon and Ketcheso (1973) where the GSAs were largest at 17°C and lower when plants were grown at lower temperature. The initial GSAs were measured between 0 and about 3 cm from the shoot base in a substrate with uniform temperature (due to the isolation layer of Perlit and the coverage with aluminium foil).…”

“…In particular in cool or phosphorus-deficient soil, more horizontal orientation of some roots may be of greater benefit. The avoidance of low subsoil temperature by increased GSAs is well documented for maize (Mosher and Miller, 1972;Onderdon and Ketcheso, 1973;Tardieu and Pellerin 1991). However, this type of response was not verified in the present set of inbred lines.…”

“…were plagiogravitropic or even diagravitropic (Feldman and Briggs 1987, Kisselbach 1999, Mosher and Miller 1972, Onderdon and Ketcheso 1973, Scott and Wilkins 1969, Suzuki and Fujii 1978, Weaver 1925. It is tempting to speculate that the more vertical orientation of modern inbred lines reflects breeders' selection during the last 30 years as suggested by Hammer et al (2009).…”

“…GSAs were largest at about 18°C. They decreased with increasing temperatures from 18 to 36°C (Mosher andMiller 1972, Onderdon andKetcheso 1973) and also with decreasing temperatures from 17 to 10°C (Onderdon and Ketcheso 1973). The temperatures during the early developmental phase, when the…”

“…It was observed already in the late 19 th century that maize roots grew more horizontally early in the season than later (Three references cited by Onderdon and Ketcheso, 1973). While the authors of these early studies assumed that the temperature gradient was responsible for this effect, later studies identified temperature per se as the cause.…”