The effect of different drought levels on root and stem architecture in some silage maize (Zea mays l.) varieties

This study aimed to determine the effects of different drought levels on the belowground and aboveground components of silage maize cultivars. Four silage maize cultivars (DKC7240, Hido, M16S45, and P2105) were used as plant material. Drought stress treatments included full irrigation, 25% water deficit, and 50% water deficit. The plants were grown in PVC tubes with a diameter of 10 cm and a length of 1 m, using a washed river sand-peat (1:1) mixture as the growing medium. The experiment was conducted in a controlled growth environment with a light intensity of 10,000 lumens, a photoperiod of 14 hours light and 10 hours dark, relative humidity of 60-80%, and temperature ranging between 25,0 27,5 °C. The trial was arranged in a factorial randomized complete block design with four replications. In the study, aboveground traits such as plant height, stem diameter, chlorophyll content (SPAD), leaf angle, pigment contents, and fresh and dry shoot weights were measured. Belowground traits included maximum root length, total root number, total root length, root diameter, root depth distribution (0-30 cm, 30-60 cm, and >60 cm), and fresh and dry root weights. As a result, significant differences were found among drought levels for plant height, stem diameter, chlorophyll content, leaf angle, pigment contents, and fresh and dry shoot weights, with a marked decrease in these traits under increased drought stress. Among aboveground parameters, significant varietal differences were observed for chlorophyll content, leaf angle, and fresh shoot weight. Among belowground parameters, significant differences were detected in maximum root length, total root length, and root fresh and dry weights under varying drought levels. As drought severity increased, maximum root length tended to increase, total root length fluctuated, while root fresh and dry weights decreased. Overall, plant growth in the aboveground parts was negatively affected starting from the 25% water deficit level. Considering the general characteristics of root and stem architecture, the P2105 and M16S45 cultivars stood out. Taking into account the effects of drought stress, it was concluded that full irrigation is necessary for the positive development of root and stem architecture in silage maize cultivars.