Effect of different soil water content effect on genotype expession in photosynthetic efficiency and leaf temperature in sunflower

Sunflower (Helianthus annuus L.) has high needs for water but can tolerate drought very well because, under stress conditions, its well developed root system can supply water and mineral nutrients from deeper soil layers. Reduced water content in soil affects plant growth and development, photosynthetic rate and causes rapid leaf senescence. In this study, we measured maximum quantum yield of photosystem II (F-v/F-m), photosynthetic performance index (PIABS) and leaf temperature (LT) on 13 sunflower genotypes at different soil water contents. By calculating stress tolerance indices (STI) of F-v/F-m and PIABS parameters we evaluated drought tolerance for every tested sunflower genotype at given soil water contents. The experiment was set up in vegetation pots in two treatments with different soil water contents (60% and 80% of field water capacity) in three replications. Based on the obtained results for Fv/Fm and PIABS and STI values of F-v/F-m and PIABS parameters, we concluded that genotypes 5 and 12 had higher tolerance at both treatments, as opposed to genotypes 2 and 13 which were less tolerant. These analyses will help breeders to select genotypes adapted to different farming areas which is, along with the use of recommended production practices, the background for profitable sunflower production

Anatomy, chlorophyll content and photosynthetic performance in current-year and previous-year Aleppo pine (Pinus halepensis Mill.) needles

Aleppo pine (Pinus halepensis) is a widespread Mediterranean woody species. Needles usually fall off the tree after the second year, which can be the reason for substantial crown defoliation under extreme environmental stress. The aim of the present investigation was to compare the anatomy, chlorophyll content and photosynthetic performance in current-year (CY) and previous-year (PY) Aleppo pine needles. Chlorophyll concentrations were determined spectrophotometrically, while photosynthetic performance was determined by measuring the increase in chlorophyll a fluorescence (the JIP test). The obtained results revealed that concentrations of chlorophylls a and b were almost twice as great in PY needles as in CY ones. The chlorophyll a to b ratio and values of the maximum quantum yield of photosystem II (Fv/Fm) showed no statistically significant difference between CY and PY needles. However, the performance index (PIABS) was significantly higher in CY needles compared to PY ones. Analysis of PIABS components revealed that CY needles had increased electron transport beyond the primary electron acceptor, QA -, which was associated with a lower value of variable fluorescence at 2 ms (VJ) in comparison with PY needles. Also, some differences were observed in needle anatomy. Current-year needles had an increased proportion of mesophyll tissue, together with decreased proportions of vascular cylinder and resin duct areas. Also, many more starch grains were present in PY than in CY needles. Based on the presented results, it can be concluded that despite considerably lower chlorophyll content, CY needles exhibited photosynthetic performance better than that of older needles, which is an unusual phenomenon in woody species.</jats:p

Relation between polyphenols content and skin colour in sour cherry fruits

Fruit skin colour plays a major role in quality assessment of food, significantly determining consumer`s choice. Colour of sour cherries depends on anthocyanins which are phenolic compounds (flavonoids) present in high amounts in fruits. The aim of this study was to determine a possible relation between polyphenols (total phenolics and anthocyanins) and colour parameters of fruit skin of sour cherries. The plant material used in this study was twenty two sour cherry genotypes from an orchard of Agricultural Institute Osijek. Total phenolics and anthocyanins contents as well as colour parameters (L*, a*, b*, h and C) of fruit skin were determined. Variability between sour cherry genotypes in total phenolics and anthocyanins as well as in colour parameters was revealed. Total polyphenols content varied from 462.7 to 1049.0 mg GAE/100 g of fresh weight, while total anthocyanins ranged from 160.1 to 495.6 mg CGE/100 g of fresh weight. A significant positive correlation was found between polyphenols and anthocyanins content. Total phenolics content had a significant negative correlation with colour parameters b* and h, while anthocyanins content negatively correlated with colour parameters L*, b* and h. According to the obtained results, genotypes Maraska, Heimanns Konservenweichsel and Rexelle are the richest genotypes in polyphenols and anthocyanins content.</jats:p

Sunflower agronomic traits in field irrigation conditions

Multi-year studies are crucial for the evaluation of sunflower hybrids and quantifying the environmental effect in the expression of genetic potential. In order to assess the adaptation of eight hybrids and test the impact of water availability on plant height (PH), head diameter (HD), 1000-grain weight (TWG), hectolitre mass (HM), seed yield (SY), oil content (OC) and oil yield (OY), a two-year study was conducted with irrigation as treatment. Analysis of variance (ANOVA) and principal component analysis (PCA) confirmed the year influence on all tested agronomic traits. According to the three-way ANOVA, irrigation significantly affected all tested traits except HD, OC and OY. All agronomic traits had lower values in both rainfed and irrigated treatment in 2014, confirming the influence of the environment. The hybrid was a significant source of variation for all traits. ANOVA and PCA grouped hybrids 1, 7, and 8 in one group and 2, 3, 4, 5, and 6 in another. The first group had lower PH, HD, TGW and SY values and higher HM, OC and OY values, and the second group had reversed traits values. Furthermore, the PCA biplot indicates SY was positively correlated with PH, HD, TGW and OY and HM was positively correlated with OC. This facilitates the breeding process because it enables indirect breeding for economically important traits such as seed yield, oil content and oil yield. As treatments were significant sources of variation for PH, HM, TWG and SY, sunflower irrigating is considered justified and can be used as an additional agrotechnical measure to target the agronomic traits. Understanding the expression of traits under rainfed and irrigation conditions will greatly help design effective breeding programs by creating hybrids suitable for cultivation in semi-arid environments

Sunflower agronomic traits in field irrigation conditions

Multi-year studies are crucial for the evaluation of sunflower hybrids and quantifying the environmental effect in the expression of genetic potential. In order to assess the adaptation of eight hybrids and test the impact of water availability on plant height (PH), head diameter (HD), 1000-grain weight (TWG), hectolitre mass (HM), seed yield (SY), oil content (OC) and oil yield (OY), a two-year study was conducted with irrigation as treatment. Analysis of variance (ANOVA) and principal component analysis (PCA) confirmed the year influence on all tested agronomic traits. According to the three-way ANOVA, irrigation significantly affected all tested traits except HD, OC and OY. All agronomic traits had lower values in both rainfed and irrigated treatment in 2014, confirming the influence of the environment. The hybrid was a significant source of variation for all traits. ANOVA and PCA grouped hybrids 1, 7, and 8 in one group and 2, 3, 4, 5, and 6 in another. The first group had lower PH, HD, TGW and SY values and higher HM, OC and OY values, and the second group had reversed traits values. Furthermore, the PCA biplot indicates SY was positively correlated with PH, HD, TGW and OY and HM was positively correlated with OC. This facilitates the breeding process because it enables indirect breeding for economically important traits such as seed yield, oil content and oil yield. As treatments were significant sources of variation for PH, HM, TWG and SY, sunflower irrigating is considered justified and can be used as an additional agrotechnical measure to target the agronomic traits. Understanding the expression of traits under rainfed and irrigation conditions will greatly help design effective breeding programs by creating hybrids suitable for cultivation in semi-arid environments.</jats:p