Phosphorus use Efficiency of Safflower (Carthamus tinctorius L.) and Sunflower (Helianthus annuus L.)

This study comparatively evaluates phosphorus (P) use efficiency of safflower and sunflower in view of identifying low input oil crops. Sunflower accumulated more P than safflower at all equivalent P supplies. Sunflower was more efficient at their best P supplies to utilize absorbed P than safflower in terms of efficiency ratio and utilization index. Yield response curves interpreting the functional relationship between nutrient supply and yield using Michaelis-Menten equation indicate that sunflower is less sensitive to inadequate P supply and thus more P-efficient than safflower with respect to yield, as the term ‘Km’ is lower for sunflower. The minimal P amount per pot required to trigger yield formation (term ‘Cmin’) was lower in sunflower than safflower. Harvest Index in sunflower out-yielded that of safflower at all P supplies. Critical deficiency contents of sunflower were lower than that for safflower. It can be concluded that safflower cannot be considered as low-input crop.     

Mechanisms of potassium uptake efficiency and dynamics in the rhizosphere of safflower and sunflower in different soils

Potassium uptake efficiency of safflower and sunflower was studied under semi-controlled conditions in loamy and sandy soils. Both species performed better in loamy soil. Safflower had higher agronomic efficiency and higher relative root length under suboptimal K supply. Safflower had higher specific root density and less root radius at all K levels. Safflower had higher relative root-shoot ratio under suboptimal K in loamy soil. Both species had similar K-influx at low and optimal K in loamy soil, while sunflower had higher influx under suboptimal and optimal supplies in sandy soil. Safflower had higher shoot demand in both soils under suboptimal and optimal K. Both species depleted similar amounts of soil solution-K under suboptimal K in sandy soil, while sunflower was more efficient under suboptimal levels in loamy soils. Sunflower depleted more extractable-K under both suboptimal and optimal K. Safflower could be considered K-uptake efficient crop.     

Effects of potassium supply on growth and yield of safflower as compared to sunflower§

Safflower may have a certain production potential under German conditions, particularly in organic farming where the putatively low nutrient requirement is highly welcomed. However, current knowledge regarding the nutrient requirements of safflower as compared to similar oil crops is limited. It was thus the aim of this study to determine the growth and yield response of safflower (Carthamus tinctorius L.) as compared to sunflower (Helianthus annuus L.) with respect to potassium (K) supply. Three safflower and two sunflower plants were cultivated in 5 L Mitscherlich pots. Both species responded strongly to increasing K supply with respect to plant growth and yield. Growth and yield of safflower increased up to 1 g K per pot, while the optimum for sunflower was 3.0 g K per pot. Safflower out‐yielded sunflower at low K supply, while at high K level, the opposite was observed. Supply of K affected virtually all yield components in both species, though to different degree. The number of capitula in safflower was only slightly affected, and the number of achenes per capitulum was only reduced under severe K deficiency, while single‐achene mass increased with increasing K supply. In sunflower, the number of achenes per capitulum strongly responded to the K supply, as did the single‐achene mass. Oil yield in safflower was affected by K deficiency mainly due to reduced achene yield, not oil concentration. However, oil yield in sunflower was severely affected by low K supply due to both reduced achene yield and lowered oil concentration. Multiple‐regression analyses indicate that in sunflower, the stem dry matter (DM) and the total amount of K accumulated in the aboveground biomass were most important, while in safflower the total amount of K and N accumulated had the highest impact. It is concluded that sunflower is more sensitive to inadequate K supply than safflower.     

Potassium efficiency of safflower (Carthamus tinctorius L.) and sunflower (Helianthus annuus L.)

The oil crop safflower may have a certain production potential under low‐input conditions (organic farming, developing countries), where the putatively low nutrient requirement is highly welcomed. However, current knowledge regarding the nutrient use efficiency of safflower as compared to similar oil crops is limited. It was thus the aim of this study to determine the potassium (K) use efficiency of safflower (Carthamus tinctorius L.) as compared to sunflower (Helianthus annuus L.). Safflower and sunflower were cultivated with increasing K supply in a mixture of equal volumes of sand, nutrient‐poor limed soil, and perlite in 5 L Mitscherlich pots. Both species responded strongly to increasing K supply with respect to growth and yield. Safflower out‐yielded sunflower at low K supply, while at high K level, the opposite was observed. Both species accumulated similar amounts of K in shoots at low K supply. Only at extremely low K supply, safflower took up more K than sunflower. However, achene yield of sunflower exceeded that of safflower at optimal and high K supply. Safflower utilized absorbed K more efficiently than sunflower to produce achene yield at suboptimal K supply in terms of both efficiency ratio and utilization index. The efficiency of a crop to use supplied or accumulated K for dry‐matter and achene production was interpreted in terms of Michaelis‐Menten kinetics, specifically addressing the shape of the yield response curve. Indeed, the efficiency of safflower to use K for growth and yield, analogue to a low K_m in enzyme kinetics, was higher than in sunflower, while the K supply or K accumulation required to initiate yield formation in safflower was significantly lower. Similarly, safflower had a lower external K requirement for achene yield than sunflower at low and optimal K supplies. It can be concluded that safflower represents a low‐input crop and outperforms sunflower on soils low in available K. The data analysis also reveals that using just one efficiency indicator is usually not sufficient to adequately describe the K efficiency of the crop under consideration.     

Viral encephalopathy and retinopathy is endemic in wild groupers (genus Epinephelus spp.) of the Algerian coast

This work describes betanodavirus infection in two species of groupers (family Serranidae) from the Algerian coast: the dusky grouper Epinephelus marginatus and the golden grouper Epinephelus costae. At necropsy, characteristic clinical signs, external injuries, clouded eyes and brain congestion, generally associated with viral encephalopathy and retinopathy (VER) infection were observed. The partial sequences of RNA1 and RNA2 from two viral strains were obtained, and the phylogenetic analysis revealed the presence of the red-spotted grouper nervous necrosis virus (RGNNV) genotype closely related to strains previously detected in groupers in the same geographic area. Results obtained in this study support the hypothesis that VER disease is endemic in the Algerian grouper population.     

EFFECTS OF PHOSPHORUS SUPPLY ON GROWTH,YIELD, AND YIELD COMPONENTS OF SAFFLOWER AND SUNFLOWER

This study comparatively evaluates the phosphorus (P) requirement of safflower (Carthamus tinctorius L.) and sunflower (Helianthus annuus L.) in view of identifying low input oil crops. Both species responded strongly to increasing P supply with respect to plant growth and yield. Yield component analysis revealed that oil yield in safflower was affected by P deficiency mainly via the number of capitula per plant followed, in consecutive order, by the number of achenes per capitulum and the single achene mass (SAM). The major yield component influencing oil yield of sunflower was the number of achenes per plant, followed by the SAM. Contribution of the seed oil concentration to overall yield variation was insignificant for both species. Path coefficient analyses indicate that in sunflower total nitrogen (N) accumulated was found to be most important, while in safflower this holds true for both the total P and N accumulated. It was concluded that safflower cannot be considered a low-input oil crop in terms of its P requirement.     

Nitrogen Use Efficiency of Safflower as Compared to Sunflower

This study compares the nitrogen (N) use efficiency of safflower and sunflower in pot experiments, as the putatively high nitrogen use efficiency of the former is not sustained. Safflower out-yielded sunflower at low N supply, while at ample supply the opposite was observed. Both species accumulated similar amounts of N per pot at equivalent N supplies, but safflower was a better N accumulator due to lower dry matter production. Safflower utilizes absorbed N more efficiently than sunflower to produce seed yield at suboptimal N supply in terms of efficiency ratio and utilization index, but the opposite holds true at optimal and high supply. Functional analysis of utilization efficiency for dry matter and seed production substantiated the higher efficiency of safflower. It is concluded that in terms of N utilization safflower represents a low input crop and outperforms sunflower with respect to seed yield on soils low in available N.