Effect of tillage systems on pea crop infestation with weeds

In a multi-year experiment, weed infestation of pea crop in three tillage systems was analyzed: a) conventional tillage (CT), b) reduced tillage (RT), and c) no-tillage (NT), and in two terms: 1) at 2–3 pea leaves stage (23–25 stage in BBCH scale) and 2) at the flat pod stage (75–79 BBCH). Treatments conducted in the CT system included shallow ploughing and pre-winter ploughing in the autumn. In the RT system, both these treatments were replaced by double cultivation, whereas only glyphosate treatment was applied in the NT system. In both terms of weed infestation assessment, the highest number and air-dry weight of weeds were determined in the RT system, lower ones in CT and the lowest ones in the NT system. In the first term, the number of weeds m^?2 in the RT system was higher by 43.9% than in NT and by 26% than in CT system. Also in the second term was the weed number m^?2 in RT higher by 58.6% than in NT and by 27.9% than in CT. Tillage systems differentiated also weed mass in pea crop. In RT, it was 4-fold higher than in NT and over 2-fold higher than in CT.     

Home range establishment and utilization by reintroduced lions (Panthera leo) in a small South African wildlife reserve

Understanding of animal spatial behavior is essential for informed management decisions. In southern Africa, reintroduction of lions (Panthera leo) to small reserves (<1000 km²) has increased since the early 2000s, however studies on their ranging behavior in these enclosed systems remain lacking. We applied Time Local Convex Hull (T‐LoCoH) methods to study the home range establishment and utilization of 11 lions reintroduced to Dinokeng Game Reserve, South Africa, during 2011 through 2014. Lions established home ranges close to their release sites and during the following 3 years their home range sizes continued to increase, but in each individual case the size remained smaller than half of the reserve area (<70 km²). Space use strategies differed between the core and the entire home range, with higher frequency of visits found in core areas. Exceptionally high rates (>60 separate visits) around the largest dam and along rivers suggest the importance of water and its surrounding vegetation in the lions' space utilization pattern. The home range size did not differ with season or sex of the individuals, whereas shifts in locations of home ranges revealed differences in the response of the 2 sexes to territorial conflicts and management interventions. Our study shows a dynamic home range utilization pattern and highlights the importance of both fine‐scale space use patterns (frequency and duration of visits) and broad‐scale home range changes in understanding the ranging behavior of reintroduced animals.     

Effects of different diets on juvenile tench, Tinca tinca (L.) reared under controlled conditions

In a laboratory experiment at 28 °C, four commercial starters (Carp Starter, Uni Starter, Perla Plus, Asta) were fed intensively to 11-month-old juvenile tench Tinca tinca of initially 41 mm TL and 0.70 g BW, over a period of 120 days. Frozen chironomid larvae were fed to fish below satiation as a reference diet for comparison of the fish body chemical composition. Final survival rates of 99–100% and satisfactory growth were attained with all dry diets, ranging from 73.3 (Carp Starter) to 84.8 mm TL (Asta) and from 5.39 (Carp Starter) to 8.09 g BW (Perla Plus). External body deformities of up to 96.4% specimens appeared in those fed Uni Starter, Carp Starter and Perla Plus, whereas 0% were recorded for Asta and chironomids. Fish in groups with deformities showed significantly elevated lipid content in their bodies, lower ash content and higher condition coefficient values. Juveniles in groups without deformities did not substantially change lipid content, but the ash content increased. Thus, among four dry diets studied, only Asta starter can be fed effectively and safely to juvenile tench reared intensively under controlled conditions.     

Stability Analysis of Agronomic Traits in Potato Cultivars of Different Origin

Potato (Solanum tuberosum ssp. tuberosum) cultivars are expected to express a stable level for traits important for growers and consumers. To investigate how this expectation was met by a set of 21 cultivars bred in Hungary, Poland and Spain, 2-year field experiments were carried out in these countries for the evaluation of tuber yield, starch content and yield, and occurrence of secondary growth of tubers. Stability in an agronomic sense was evaluated by the analysis of genotype by environment interaction (GE) using the Scheffé-Caliński mixed model. Unstable trait expression was indicated by the statistically significant share of GE in the variability contributed by a specific cultivar. This instability could lead to either complete or partial unpredictability. Stable trait expression was observed for 6–11 cultivars, depending on the trait. A significant genetic factor, which indicates broad adaptation, was rarely found. Stable expression of tuber yield occurred together with stable or predictable expression of both starch content and yield. Unstable expressions of tuber and starch yield were also associated. The stability or instability of secondary growth was not associated with stability or instability of the other measured traits. Analysis of GE interaction was useful for identifying stable or unstable responses and revealed the presence of incomplete stability or partial unpredictability as intermediate types of reaction.