[en] Crop modelling is considered an essential tool of planning. The automation of irrigation scheduling using crop models would contribute to an optimisation of water and fertiliser use of protected crops. To achieve this purpose, two experiments were carried. The first one aimed at determining water requirements and irrigation scheduling using climatic data. The second experiment was to establish the influence of irrigation interval and fertigation regime on water use efficiency. The results gave a simple model for the determination of the water requirements of protected cucumber by the use of climatic data: ETc=K* Ep. K and Ep are calculated using climatic data outside the greenhouse. As for water use efficiency, the second experiment highlighted the fact that a high frequency and continuous feeding are highly recommended for maximising yield. (author)

[en] The Oriental fruit moth (OFM) is a major insect pest of peaches in Bulgaria. Its control usually requires several insecticide treatments per season. This, however, gives rise to serious toxic residue problems. A program for suppression of OFM populations involving the use of sterile-insect technique (SIT) has been developed as an alternative to the chemical methods for OFM. Relevant information regarding laboratory rearing, radiation and basic biology are presented here. Expected effects of some release programs are modelled using appropriate mathematical simulations. Results obtained in a small field experiment showed high efficacy of a program integrating F₁ male sterility technique and classic SIT. (author)

[en] Spodoptera litura was reared on natural food (castor leaves, Ricinus communis) and on a several semi-synthetic diets using quasi mass rearing techniques. The effect of the different diets and rearing regimes on S. litura growth, development, reproductive competence and adult behaviour was measured. Spodoptera litura reared from a modified chickpea-based diet provided the greatest growth index and index of adequacy. These studies were conducted as a prerequisite for the evaluation of F₁ sterility technique. (author)

[en] The management of cotton bollworms in a semi-isolated area through the use of inundative releases of the egg parasitoid Trichogramma chilonis (Hymenoptera: Trichogrammatidae) in conjunction with pheromones suppressed populations of the pink and spotted bollworms to sub-economic levels. The parasitoid was more effective against pink bollworm than spotted bollworm. Applications of either pheromones or parasitoids by themselves were less effective when compared to the combined treatment. The level of parasitism in the cotton field was comparatively low in June and July but gradually increased during August and September. Maximum parasitism was recorded in November. Studies indicated that temperature affected the establishment of the parasitoid, and populations increased significantly when favourable conditions prevailed in the cotton field. (author)

[en] Studies were conducted with codling moth, Cydia pomonella (L.), to examine the effects of gamma radiation on fertility and reproductive behaviour. Data accumulated during these studies showed that egg production and hatch decreased with increasing radiation dose. Females were more sensitive to radiation treatment than were males. A dose of 150 Gy caused 100% sterility in females and significantly reduced fecundity, and a dose of 350 Gy reduced male fertility to less than 1%. Radiation dosages up to 400 Gy had no adverse effect on male longevity or competitiveness in cages using laboratory reared moths. However, males exposed to a dose of 350 or 400 Gy mated fewer times than unirradiated males. (author)

[en] Diamondback moth (DBM), Plutella xylostella males irradiated with 100 Gy and larval parasitoids (Cotesia plutellae) were studied for their potential to control DBM in cabbage fields of Nyaung-Le-Bin Township, Bago Division. The following treatments were evaluated as control tactics: release of irradiated male DBM, augmentative release of parasitoids, and combined release of irradiated male DBM and parasitoids. These treatments reduced the larval population of feral DBM. (author)

[en] A number of experiments were conducted to investigate the influence of different N rates applied through drip irrigation on the growth and N uptake by tomato, pepper, cucumber, melon and eggplant under greenhouse conditions. It was found that, for tomato, the % NUE was significantly increased by applying the N fertilizer through fertigation (53.9%) as compared to the soil application (34.0%) at 100 mg N/L. In general, any further increase of N fertilizer did not have an improving effect on the tomato yield. With pepper, the % NUE was significantly increased by applying the N fertilizer in the irrigation water (49.2%) as compared to the soil application (33.9%) at the same N level (140 mg N/L), being the optimum N rate under our greenhouse conditions. At a fertilization level of 100 mg N/L with fertigation, the % NUE was significantly increased as compared to the soil application. With respectively cucumber, melon and eggplant; the % NUE with fertigation was 63.4, 21.4 and 50.8%, while with soil application it was 34,0 11.0 and 18.8%. (author)

[en] Cucumber and tomato are the most important protected vegetables in coastal Lebanon. Recent research established that in these intensive systems, irrigation and fertilization are still empirically applied. Techniques such as fertigation are used but associated to traditional practices of soil application of fertilizers and animal manure addition. In 1997, a pot experiment was conducted in order to find the optimal irrigation frequency and modality of fertigation. For this, four frequencies of irrigation were combined with two modalities: discontinuous irrigation as practiced by the growers and continuous irrigation, as recommended by the scientists. In these closed-system conditions, the frequency of irrigation influenced the dry matter production. In addition, the percentages of nitrogen derived from fertilizers were very high, from 89 to 95%. The discontinuous modality allowed for greater nitrate leaching. The evaluation of the main findings for plants grown in the soil, was conducted in 1998, in a greenhouse, 35 km north of Beirut. The treatments were reduced to two frequencies of irrigation combined with the two modalities of fertigation. The objectives were to assess, with the use of ¹⁵N labelled fertilizers, the most efficient treatment as far as plant performance and losses from the plant-soil system are concerned. (author)

[en] To measure the N uptake and utilisation by plants, labelled ¹⁵N has been used. In this paper ¹⁵N-labelled urea was applied to cucumber under protected cultivation for two seasons, 1996/97 and 1997/98. Four levels of urea-N (0, 200, 400 and 600 kg N ha ^-1) were used in a complete randomised block design with 8 replicates. The experiment was conducted in the UAE at the Hurnraniyah Agriculture Research Station (HARS) in collaboration with the International Atomic Energy Agency (IAEA). From the obtained results it was clear that the average optimal fertiliser rate was 200 kg N ha ^-1. The N yield in the plant dry matter (fruits, shoots and roots) was 6.13 g N/plant under the specific experimental conditions (the area per plant was 1.23 m² ). Using ¹⁵ N, it was found that the fertiliser N yield obtained for the same plant parts was 1.82 g N/plant. (author)

[en] We investigated various effects of gamma radiation on the carob moth, Ectomyelois ceratoniae, treated with 200-600 Gy at different pupal ages. Irradiation resulted in a decrease of adult emergence. This effect was both dose and age dependent. At 500 and 600 Gy, no pupae developed into normal adults when treated at the age of 4-5 days. Only 6% normal adults emerged when the pupae were treated at the age of 6-7 days with 500 Gy. When 8-9 d old pupae were irradiated with 500 and 600 Gy, 30% and 10% normal adults emerged, respectively. Other emerged moths exhibited various malformations, mostly wing deformities. When pupae were treated with 400 or 500 Gy, fecundity and fertility of both untreated females mated with irradiated males or irradiated females mated with untreated males were drastically reduced. When 9-10 d old pupae were irradiated with 200, 250 and 300 Gy, adult morphology, fecundity, fertility and egg hatch were slightly affected. Mating behaviour of irradiated males also was affected. Competitiveness of males irradiated with sub-sterilizing doses varied depending on irradiation dose and number of insects present in the mating cages. A significant reduction of competitiveness was observed in males treated with ≤300Gy. (author)