Influence of nitrate concentration at the root surface on yield and nitrate uptake of kohlrabi (Brassica oleracea gongyloides L.) and spinach (Spinacia oleracea L.)

1991 ◽  
Vol 135 (2) ◽  
pp. 205-211 ◽  
Author(s):  
B. Steingrobe ◽  
M. K. Schenk
Sjemenarstvo ◽  
2021 ◽  
Vol 31 (1-2) ◽  
pp. 29-40
Author(s):  
Dijana Horvat ◽  
Helena Tomić-Obrtalj ◽  
Marina Palfi ◽  
Ivana Koprivnjak ◽  
Iva Rojnica

Sjeme povrtnih vrsta namijenjeno vrtlarima hobistima uglavnom je iz uvoza, kategorije standard i pakirano u sitnim pakiranjima. Uvoznici koji prepakiravaju sjeme obavezni su nakon pakiranja ispitati klijavost. Neprodane količine sjemena povlače se s tržišta na kraju sezone i plasiraju u iduće dvije do tri sezone bez kontrole klijavosti te se događa da sjeme u prodaji ima lošu klijavost ili uopće nije klijavo. Cilj istraživanja bio je ispitati klijavost sjemena 24 povrtne vrste na uzorcima partija sjemena skladištenih u klimatiziranom skladištu i na uzorcima istih partija koje je na tržištu dvije vegetacijske sezone te usporediti s ispitanom klijavosti nakon uvoza. Istraživanjem je utvrđeno da klijavost sjemena celera listaša (Apium graveolens var. secalinum L.), celera korjenaša (Apium graveolens L.), peršina listaša (Petroselium crispum ssp. crispum L.), poriluka (Allium porrum L.), boba (Vicia faba L.), paprike (Capsicum annuum L.) i špinata (Spinacia oleracea L.)pada neovisno o uvjetima skladištenja, dok uvjeti skladištenja značajno utječu na klijavost kupusa (Brassica oleracea L.), brokule (Brassica oleracea L. var. italica), salate (Lactuca sativa L.) i cikle (Beta vulgaris L. var. conditiva). Od ukupno 24 partije sjemena povrtnih vrsta uzorkovanih u skladištu dorađivača (uvoznika) njih 46% nakon 20 mjeseci ne zadovoljava propisanu minimalnu klijavost, dok od istih partija sjemena uzorkovanih u skladištu laboratorija (kontrolirani uvjeti) ne zadovoljava njih 29%. Skladištenjem sjemena na temperaturi 15° C na tamnom i suhom mjestu te kontrolom klijavosti nakon svake vegetacijske sezone može se značajno utjecati na kvalitetu sjemena povrtnih vrsta na tržištu.


2020 ◽  
Vol 38 (2) ◽  
pp. 205-217
Author(s):  
Zelma Beatriz Peñafiel-Sandoval ◽  
José Iannacone

Agricultural intensification has led to an elevated use of pesticides and fertilizers such as urea, without considering the negative effects these products can cause, such as acidification of the soil and the entry of lead (Pb) into the trophic chain. The objective of this research was to determine the effect of urea on the absorption of lead (Pb) in the leaf structure of corn (Zea mays L.), spinach (Spinacia oleracea L.), and cabbage (Brassica oleracea L.). These three plant species were exposed to five different concentrations of urea and a constant concentration of Pb in the form of Pb acetate for 93 days. The effect of urea and Pb was determined through analysis of the leaf structure. The results showed an increase in the dry weight of corn, whereas in spinach (T4) (1.5 g urea kg-1 of soil plus 0.5 g Pb kg-1 of soil) dry weight decreased as well as the fresh weight and foliar area. An increase in the chlorophyll index in corn, spinach, and cabbage was observed in the treatments with urea, and there was an influence on soil acidification. We also observed that spinach concentrated more Pb (T4) in its foliage at higher rates of N application. The idiosyncratic nature of the crop combined effects of Pb and N highlights the need for more research on this subject.


HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 480e-480
Author(s):  
Nancy H. Furness ◽  
Mahesh K. Upadhyaya ◽  
Douglas P. Ormrod

Relative sensitivity of selected vegetable and weed seedlings to ultraviolet-B (UV-B) radiation (280–320 nm) was investigated. Seedlings were grown for 4 weeks in a greenhouse, in chambers equipped with UV-B-emitting fluorescent tubes and Mylar (control) and cellulose acetate (UV-B) filters. UV-B radiation reduced seedling height, leaf area, and leaf fresh weight in tomato (Lycopersicon esculentum `Cour Di Bue'), broccoli (Brassica oleracea var. Italica `Purple Sprouting'), cabbage (Brassica oleracea var. Capitata `Red Drumhead'), and cucumber (Cucumis sativus `Straight Eight'), leaf area and leaf fresh weight in beet (Beta vulgaris `Cylindra' and `Early Wonder'), seedling height and leaf area in spinach (Spinacia oleracea `Long Standing Bloomsdale'), lettuce (Lactuca sativa ``Red Salad Bowl Everest') and `Savoy' cabbage, and seedling height in `Chinese Tip Top' cabbage and lettuce (`Saladin'). `Winterton' cabbage was not affected. UV-B radiation decreased leaf area and leaf fresh weight in common chickweed (Stellaria media) and corn spurry (Spergula arvensis) and seedling height in green foxtail (Setaria viridis) and redroot pigweed (Amaranthus retroflexus). Tillering was stimulated in response to UV-B in green foxtail. There was no effect of UV-B on lady's-thumb (Polygonum persicaria) growth. Leaf number was not affected by exposure to UV-B in any species. The differential morphological sensitivity of vegetable and weed seedlings may result in altered competitive relationships under enhanced UV-B levels expected with the depletion of the earth's ozone layer.


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