Carla do Carmo Milagres

Relationship between fruit maturation stage and physiological quality of physic nut (Jatropha curcas L.) seeds

The physic nut (Jatropha curcas L.) has great potential for use in biodiesel production due to the high oil content of its seeds. Production of high quality seeds depends upon the appropriate time of harvest. A field experiment was carried out to monitor the maturation process of physic nut seeds and to establish the ideal harvest time of the seeds based on external fruit color. Fruits were collected at different maturation stages based on the external color: green, yellow-green, yellow, yellow-brown and brown. Seeds were extracted manually and, after natural drying, were submitted to the following tests and determinations: moisture content and dry matter, germination, first count seedling emergence, seedling growth, accelerated aging, electrical conductivity, the weight of thousand seeds and oil content. A randomized design was used with four replications. Data were subjected to analysis of variance and, for each test, treatment means were compared by Tukey test at 5% probability. Physic nut seeds with high physiological quality are obtained from yellow and yellow-brown fruits. Seeds from green fruits have lower physiological quality, dry matter and oil content than the other maturation stages. The seeds obtained from brown fruits have a high germination potential, but have low vigor in relation to yellow and yellow-brown stages.

Basal defoliation and their influence in agronomic and phytopathological traits in tomato plants

The incidence of leaf diseases is one of the main factors limiting the tomato crop production, increasing the production cost due to excessive pesticide application. The basal leaf removal could reduce inoculum sources, disease severity and contribute to reducing the use of pesticide. Aiming to evaluate the efficiency of this practice on the reduction of tomato leaf diseases and the effect in the quality and in the productivity of the tomato plants for in natura consumption, two experiments were carried out to test four levels of basal leaf removal. Basal leaves removal, at fruit harvesting, is efficient in reducing the infected plant area by disease, what can mean smaller disease severity and least inoculum source in the field. Also, the all basal leaf removal does not affect yield and quality of the tomato fruits. Other studies are necessary to evaluate the effect of adopting this practice in different planting dates, spacing, varieties, successive plantings and the financial viability of adopting this practice.

Assessment of the natural control of Neoleucinodes elegantalis in tomato cultivation using ecological life tables

ABSTRACT Life table studies allow for a better understanding of mortality factors against insect pests. It assesses each mortality factor and its parameters in population suppression. Neoleucinodes elegantalis (Guenée) (Lepidoptera: Crambidae) is one of the major pests of solanaceous crops in South America. The background information provided by life table studies might be used for developing management strategies for controlling N. elegantalis. Thus, the aim of this study was to identify and quantify the mortality factors of N. elegantalis in tomato cultivation by using life tables. The results were obtained from 64 ecological life tables. The mortality factors for eggs, larvae and pupae were due to rain, fruit drop, predation, parasitism and unviability caused by physiological disorder and diseases. The percentage of total death for eggs, larvae and pupae were 64.2%, 24.9% and 5.93%, respectively. The highest rates of mortality were caused by predation and parasitism. Thus, mortality of N. elegantalis caused by natural enemies might be used as a basis for determining which methods are better for controlling N. elegantalis while having the lowest possible impact on its natural enemies.

Mini-tubérculos de batata semente básica produzidos sob parcelamento e doses de nitrogênio em substrato

This study aimed to evaluate the effect of both N fertilizer rates and split applications on yield of basic class seed potato mini-tubers. Treatments were four N rates (0, 115, 230, 460 mg L-1) and five split modes: M1 [10% at planting + 90% at 21 days after plant emergence (DAE)]; M2 [10% at planting + 3% daily (21 to 51 DAE)]; M3 (50% at planting + 50% at 21 DAE); M4 [50% at planting + 1.6% daily (21 to 51 DAE)]; M5 (100% at planting). The experiment was set up in randomized blocks design in factorial arrangement 4x5 (rates x modes), with three replications. We planted the cultivars Atlantic and Opaline, using basic commercial mini-tubers. Plants were grown in 3 L pots containing commercial substrate. At 25, 35 and 56 DAE we assessed the content (TN) and amount of N (QNA) in the leaf. At harvest, 86 DAE, we determined the number of tubers and fresh and dry tubers mass. For both cultivars, in the early stages of plant growth, neither combination of rate and split modes of nitrogen affected the TN. In subsequent evaluations, TN increased with increasing dose of N. In both cultivars, QNA was not affected by application of diluted doses of N. No combination of dose and split mode of nitrogen fertilizer application influenced the number of tubers. When there was effect of N rate on tuber mass, the zero rates provided the highest value of this variable. The concentrated application of N at the tuberization time is harmful for the plant because it reduces both dry and fresh tuber masses.