Changes in the leaf gas exchange of common winter wheat depending on the date of application of a set of herbicides

Z. Petrova1*, Z. Zlatev2

1Dobrudzha Agricultural Institute, 9520 General Toshevo, Bulgaria
2Department of Plant Physiology, Faculty of Agronomy, Agricultural University, 12 Mendeleev, 4000 Plovdiv, Bulgaria

Abstract. The aim of this investigation was to determine the effect of the date of application of a set of herbicides on the foliar gas exchange of common winter wheat. The investigations were carried out in 2013 and 2014 at Dobrudzha Agricultural Institute (DAI). The following herbicides were used: Derby super VG (33 g/ha), Granstar 75DF (15 g/ha), Lintur 70VG (150 g/ha), Secator ОD (100 ml/ha), Mustang 306.25 СК (800 ml/ha), Palace 75WG+oil (250+1000 g/ml/ha) and Husar Мax ОD (1000 ml/ha) from the group of suflonylureas with various mechanism of action. The preparations were applied at two stages of common winter wheat cultivars Aglika and Enola (stages 29 and 32 according to Zadoks). The indices of leaf gas exchange were followed: rate of net photosynthesis (А), intensity of transpiration (E), stomatal conductivity (gs) and intercellular concentration of СО2 (ci). It was found that the later application (stage 32) of Lintur 70VG and Mustang 306.25СК caused visible signs of phytotoxicity. These were expressed as anthocyanin pigmentation of leaves and spikes and as partial to full sterility of spikes, stronger after using Lintur VG and weaker after Mustang 306.25СК. Following a delayed application of the herbicides, slower rate of growth of plants was observed, as well as disturbances in the parameters of foliar gas exchange. The high rate of A at comparatively low E and gs and the low ci in the weeded check indicated that the plants spent considerable energy resources to overcome the negative effect of weeding.

odbutton6

Effect of organic fertilizers on photosynthesis of young tomato plants (Lycopersicon esculentum Mill.)

Z. Zlatev, V. Popov
Abstract. The aim of this study was to investigate the effect of organic fertilization on photosynthesis of young tomato plants (Lycopersicon esculentum Mill.) – cv. Trapezica and cv. Yana. The field experiments were carried out at the experimental field of the Agroecological Centre of Agricultural University-Plovdiv, which is certified as an organic farm. For the purpose of the research, two biofertilizers were used – Emosan and Lumbrical (both authorized for use in organic farming). The results indicated that the applying of organic fertilizers increased leaf gas exchange parameters and pigment content in the studied cultivars. It is established that there was a positive effect of biofertilizers upon the functional activity of the photosynthetic apparatus.odbutton

Drought-induced changes in photosynthesis of young cowpea plants

K. Uzunova, Z. Zlatev
Abstract. Laboratory experiments were conducted to study the effect of soil drought on photosynthesis of young cowpea plants (Vigna unguiculata L.) – cv. Lagoa and cv. 1183. Drought conditions were imposed on 2-week-old plants by withholding water for 10 days. It was established that drought seriously inhibits net photosynthetic rate (A) and transpiration rate (E). Minimal (F ) fluorescence increases and maximal (F ) and variable (F ) fluorescence decrease. In light 0 m v adapted leaves a significant decrease in quantum yield (Y), photochemical quenching (qP) and electron transport rate (ETR) of PSII occurred. In conclusion, it is considered that the photosynthetic apparatus of cv. Lagoa is more tolerant and of cv. 1183 more sensitive to drought.

odbutton

Leaf gas exchange and water relations of two sunflower cultivars under drought

Z. Zlatev

Abstract. Laboratory experiments were conducted to study the effect of soil drought on leaf gas exchange and water relations of young sunflower plants (Helianthus annuus L.) – cv. Favorit and cv. Albena. Similar changes were established in the parameters tested. Significant inhibition of net photosynthetic rate, transpiration intensity and stomatal conductance were observed. Cultivar’s differences were also established, particularly marked in terms of transpiration intensity and stomatal conductance, which were more strongly inhibited in plants of cv. Favorit. Among the water exchange parameters, it was the leaf water potential (Ψ) that changed most in both cultivars, becoming more than two times lower.

odbutton

Changes in chlorophyll fluorescence and leaf gas exchange of durum wheat under low positive temperatures

Z. Zlatev, T. Kolev

Abstract. Changes of functional activity of the photosynthetic apparatus of four durum wheat cultivars under low positive temperature stress were studied. Parameters of chlorophyll fluorescence in dark-adapted and light-adapted leaves were analyzed, as well as leaf gas exchange. The applied stress induced an increase in F accompanied by a decrease in F in the second leaf of the studied cultivars. At the end of the stress period plant of cv. Reamur and cv. Exodur limit 0 m to greater extent transpiration intensity and stomatal conductance, this leads, together with significantly reduced activity of PS2, to substantial inhibition of net photosynthetic rate (P ). It is established, that photosynthetic apparatus of cultivars Karur and Pescadou is more tolerant and photosynthetic apparatus of N cultivars Reamur and Exodur is more sensitive to low positive temperature stress.

odbutton