In the Netherlands about 2000 ha of glasshouses is equipped with supplementary assimilation light (SL), which is about 19% of the total glasshouse area. Besides increased production, SL results in improved product quality, a better control of yield and quality, possibilities for earlier or year-round production and a more regular labor requirement. In this paper several recent experiments with different strategies of SL (33 up to 210 µmol m -2 s -1 ) for tomato, sweet pepper, cucumber and eggplant are presented and discussed. In general, it was concluded that SL was not economically feasible. For cucumber SL can only be attractive if the crop is grown at high plant density and according to the high-wire system. Based on 3 plantings per year, a production of 147 kg m -2 (360 cucumbers) is possible with 210 µmol m -2 s -1 SL during 3000 h/year. Application of 50% of the light within the crop (interlighting) by fluorescent tubes instead of only HPS-lamps above the crop, did not improve production but improved fruit quality in cucumber. Mobile lamps are sometimes used instead of fixed lamps. For sweet pepper and tomato, a fixed-lamp installation was economically more feasible than mobile lamps when compared at the same light intensity. A dynamic simulation model was used to predict effects of different lighting strategies at 500 and 1000 ppm CO 2 on potential production. Maximum levels of 110, 64 and 168 kg m -2 year -1 were calculated for tomato, sweet pepper and cucumber, respectively. INTRODUCTIONThe glasshouse industry in the Netherlands is the largest worldwide with 10.500 ha and a production value of 5.9 billion euro. About 40% of the glasshouse area is used for vegetable production, mainly tomato, sweet pepper and cucumber. Ornamentals, both cut flowers and pot plants are grown on the remaining 60%. Main cut flowers are roses and chrysanthemum, whereas ficus, kalanchoe and begonia are the most important pot plants considering cultivation area. Although the total glasshouse area is rather constant, the area of individual companies is growing fast. For vegetables, in 1995 442 companies (9% of the total) were larger than 2 ha, whereas in 2004 this was 686 (26% of the total). Among these are several companies larger than 20 ha. Annual production levels in the Netherlands belong to the highest in the world, e.g. for tomato (up to 70 kg m -2 ), cucumber (up to 90 kg m -2 ), large-sized cut roses under supplementary assimilation light (SL; 270 stems m -2 ) and cut chrysanthemum under SL (250 stems m -2 ). A major threat to the glasshouse industry is its high energy use. The equivalent of 4.3 × 10 9 m 3 of natural gas is used annually to heat the glasshouses, resulting in an average gas input of 41 m

Physiological status of chrysanthemum cuttings during rooting process highly influences plant growth and flower production. Amongst other aspects, rooting capacity of the cuttings is the most important. Rooting capacity is influenced by environmental conditions such as growing medium and nutrition. The study was aimed to analyze the effects of different types of media, fertilizer concentration, and frequency of fertilizer application on the rooting capacity of chrysanthemum cuttings. The experiment was conducted at the Segunung Experimental Station of the Indonesian Ornamental Crops Research Institute from February to May 2005. The treatments consisted of four different rooting media, i.e. carbonized rice husk, coco peat, perlite, and mixture of perlite and vermiculite (1:1 v/v); two concentrations of NPK (25:7:7) fertilizers, i.e. 1.75 and 2.5 g 1-l; and four frequencies of fertilizer application, i.e. every 1 day, 2 days, 3 days, and 4 days. The experiment was designed in a completely randomized block with four replications. Parameters observed were rooting capacity and cutting performances such as cutting height, cutting diameter, number of leaves, number of visible roots, and root length at 16 days after planting. The results showed that chrysanthemum cuttings rooted in carbonized rice husk had better performance than those rooted in coco peat, vermiculite, and mixture of perlite + vermiculite. Higher concentration of fertilizer solution up to 2.5 g l-1 also gave significant effect on the root formation and further root growth of cuttings. However, the rooting capacity of cuttings was not affected by the frequency of fertilizer application. This study implied that carbonized rice husk growing medium supplemented with NPK (2.5 g l-l) every 4 days during rooting period is the choice for traditional chrysanthemum growers to increase the perform-ance and quality of the cut flowers.

Di Indonesia, penelitian tentang pengaruh jumlah cabang per tanaman sangat terbatas dan baru dilakukan pada satu varietas paprika, yaitu cv. Ferrari. Dalam rangka meningkatkan pilihan petani terhadap varietas yang dibudidayakan, penelitian tentang pengaruh jumlah cabang per tanaman pada pertumbuhan dan hasil tiga varietas paprika perlu dilakukan. Penelitian dilaksanakan di Rumah Plastik kayu-metal, Kebun Percobaan Balai Penelitian Tanaman Sayuran, Lembang (1.250 m dpl.), Jawa Barat dari bulan Juni 2007 sampai dengan Februari 2008. Penelitian menguji dua faktor perlakuan, yaitu (1) jumlah cabang per tanaman dengan dua taraf, yaitu dua dan tiga cabang per tanaman serta (2) varietas dengan tiga taraf yaitu varietas Spider, Chang, dan Athena. Percobaan menggunakan rancangan acak kelompok dengan tiga ulangan. Hasil penelitian menunjukkan bahwa jumlah cabang per tanaman berpengaruh nyata terhadap pertumbuhan dan hasil paprika. Tanaman paprika dengan sistem tiga cabang menunjukkan pertumbuhan yang lebih tinggi dan berbeda nyata dibandingkan dengan sistem dua cabang terutama pada  umur 11 minggu setelah tanam. Tanaman paprika dengan sistem tiga cabang memberikan hasil total dan hasil kelas buah &gt;200 g berturut-turut lebih tinggi  yaitu sebesar 9,3 dan 9,1% daripada tanaman paprika dengan dua cabang. Total hasil varietas Athena dan Spider lebih tinggi dan berbeda nyata dibandingkan dengan varietas Chang, tetapi varietas Chang menghasilkan jumlah buah yang lebih banyak dibandingkan dengan dua varietas lainnya. Hasil penelitian ini dapat digunakan sebagai rekomendasi untuk pemilihan varietas dan teknik budidaya paprika dalam kondisi rumah plastik di Indonesia.<br /><br /><br />In Indonesia, research on the effect of stem number per plant is very limited and it was conducted only in one sweet pepper variety namely Ferrari. In order to increase the possibility of farmers to choose good cultivated varieties, an experiment needs to be conducted to determine the effect of stem number per plant on the growth and yields of three sweet pepper varieties. This experiment was carried out in the wood-metal plastichouse at the experimental field of the Indonesian Vegetable Research Institute (IVEGRI), Lembang (1,250 m asl.), West Java from June 2007 to February 2008. Two factor treatments tested were (1) number of stem per plant with two levels i.e. two stems and three stems per plant and (2) varieties of sweet pepper i.e. Spider, Chang, and Athena. The treatment combinations were arranged in a completely randomized block design with three replications. The results indicated that number of stem per plant significantly affected the growth and yield of sweet pepper. The plant height of sweet pepper plants grown with three stems were significantly higher than those with two stems, especially after 11 weeks after planting. The plants grown with three stems per plant gave higher total yield and yield of class &gt;200 g up to 9.3 and 9.1%, respectively than the ones grown with two stems per plant. The total yield and yield of class &gt; 200 g of Athena and Spider were significantly higher than those of Chang. However, Chang yielded more number of fruits compared to Athena and Spider. The results can be used as a recommendation in variety selection and cultivation of sweet pepper grown under plastichouse  conditions in Indonesia.<br /><br />

Glassiness, a physiological disorder occurring in greenhouses between November and February under low natural light conditions, is probably due to an imbalance between water uptake and transpiration. Eight greenhouse experiments were carried out during winter. Experiments with soil-grown plants showed that soil compaction and nitrogen supply were negatively correlated with the amount of glassiness whereas the amount of nightly outgoing radiation (from inside the greenhouse) was positively correlated with glassiness. Studies using the nutrient film technique showed that the positive effect of nitrogen was probably due to higher salt concentration rather than a specific effect of NO3-. Clear cultivar differences were observed with Dalida, Mistra and Rolinda showing less glassiness than Renate, Amanda Plus and Decisco. High soil compaction, high plant temperature, tolerant cultivars and higher total salt concentration could all be used to reduce glassiness. (Abstract retrieved from CAB Abstracts by CABI’s permission)

In a series of greenhouse experiments (winter and spring, 1980-85), significant differences in frequency of (undesirable) open head formation were detected among 6 cultivars. Starlina, Aubade, Cristallo and Kellys showed 18-38% open heads, whereas Sonia and Marbello had