A field experiment was carried out on a saline calcareous soil cultivated
with sweet pepper plants (Capsicum annuum L.) under drip irrigation system at a
private farm, Nubaria region, El Beheira Governorate, Egypt during two
successive seasons 2009 and 2010. The aim target of the current study was
identified the effect of soil application for different N-source of (ammonium
nitrate, calcium nitrate and ammonium sulfate) as solely treatments or in
combination with some bio-organo-stimulants (potassium humate, potassium
citrate or yeast) on the plant growth parameters, nutritional status, fruit yield and
its quality as expressed by titratable acidity, total soluble solids, total
carbohydrates, vitamin C, anthocyanin, total polyphenols, and mineral contents
(Ca and K), fruit nitrate, with a special reference to the associated effects on the
soil properties and available nutrient contents. The mineral N, P and K fertilizers
in their different forms were applied as the recommended rates after Ministry of
Agriculture, i.e., 100 kg N fed-1, 48 kg K2O fed-1 and 15.5 kg P2O5 fed-1, while
potassium humate at 0.5 g L-1, potassium citrate at 1.0 g L-1 and yeast at 2 g L-1,
which added at the same time of applied nitrogen sources through the drip < br />irrigation system. Taking into consideration K-amount of (K-humate+K-citrate)
represents 25% of the applied recommended K-rate.
The obtained results indicated that there were significantly increases in soil
organic matter and available nutrients contents as a result of applied different Nsources and bio-organo-stimulants, with a superiority effect for the combined
treatment of (ammonium nitrate+ K-humate). On the other hand, soil pH and
ECe were took place a parallel opposite trend, where their values exhibited
significantly decreases, with a superiority effect for the previous combined
treatment. It is noteworthy to mention that, it could be categorized the applied
treatments according to their superiority effects on the studied soil properties into
two ascending orders: Am-Ni > Am-Su > Ca-Ni and K-Hu > K-Ci > Ye as solely
treatments of N-sources and bio-organo-stimulants, respectively. The second
order: (Am-Ni+K-Hu) > (Am-Ni+K-Ci) > (Am-Ni+Ye), (Am-Su+K-Hu) > (AmSu+K-Ci) > (Am-Su+Ye) and (Ca-Ni+K-Hu) > (Ca-Ni+K-Ci) > (Ca-Ni+Ye) as
the applied combined treatments.
As for plant parameters of sweet pepper, the data showed that the effective
role of the applied treatments on leaf number/plant, branch number/plant, plant
height, leaves weight/plant and nutritional status as well as fruit yield and its
quality parameters behaved a similar parallel trend as was achieved with the
studied soil properties. That was true, since the achieved favourable amelioration
in soil properties was positively effected on the plant growth parameters, fruit
yield and its quality. Moreover, such findings are confirmed by the best effective
role of the combined treatment (ammonium nitrate+ K-humate) that was also
achieved the greatest values in plant growth parameters as well as fruit yield
and quality of sweet pepper.