RESPONSE OF PEPPER TO BORON AND SALINITY UNDER GREENHOUSE CONDITIONS

     Boron toxicity occurs in semiarid and arid regions when there are high levels of boron (B) in the soil or irrigation water, particularly in areas with little or no drainage. The objective of the present study was to examine the combined effect of B and salinity on the dry matter production and yield of bell pepper grown under greenhouse conditions, in order to determine the toxicity threshold levels of B and salt. Plants were grown for 200 days on a perlite culture. Sixteen treatments comprised 4 concentration levels of sodium chloride (5, 15, 25 and 35 mM) and 4 concentration levels of B (0.046, 0.092, 0.185 and 0.37 mM). The Ca concentration was constant (5 mM). Shoot and yield weights were not influenced by B concentrations of up to 0.37 mM (4 mg/l) even at the highest salinity level. However, the dry matter weights of the shoot and fruit yield decreased as the sodium chloride concentration increased. The B concentration in the root was correlated positively to B concentration in the irrigation water at any given sodium chloride level. The same effect was observed to a lesser extent in the leaves. Increasing sodium chloride concentration reduced B uptake by the plants. These results may indicate that salinity increases the tolerance of bell pepper to B although it also reduces yields.

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