pH optima for citrus inferred from the anatomical records of young roots of trifoliate orange budded with Satsuma mandarin [Japan]
1999
Mohammad, P. (Matsuyama (Japan). United Graduate School of Agricultural Sciences) | Shiraishi, M.
The anatomy of young roots of trifoliate orange budded with satsuma mandarin cultured hydroponically under pH 4.5-5.6, 6.0-5.3 and 7.5-7.6 were investigated to know the pH optima for this plant. Under pH 4.5-5.6, root tips were pointed and meristematic zone appeared wider. Starch grains were found on the rootcap and cortical cells apart from the tip but were absent completely from the cortical cell files close to the root apex. These characteristics remained similar along the exposure time. Under pH 6.0-6.3, roots were subjected to gradual shortening of growing zone followed by epidermal and root tip injuries on longer induction. Starch grain content in the cortical cells gradually increased up to 10 days of induction followed by conspicuous decrease, especially near the injured epidermis. The adverse effects of pH 7.5-7.5 started at short exposure resulting the severe sloughing of rootcap cells and bulbous structure of root tip. The epidermal injury also became conspicuous even within 3 days. The root apex secreted mucilaginous substances which were followed by injuries. Numerous starch grains were initially accumulated in the cortical cells but degraded completely at longer exposures. The cortical cells remained elongated and cell length gradually increased from the root apex towards the root base at pH 4.5-5.6. In contrast, the cells turned to round and their lengths became higher near the root apex in pH 6.0-6.3 and 7.5-7.6 compared to pH 4.5-5.6.
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