PERTUMBUHAN ANAKAN KOPI (Coffea arabica Lin.) BERBASIS SISTEM AGROFORESTRI DI HUTAN RAKYAT CIMARIAS SUMEDANG

In the recent years, there is a significant increase on economic value of coffee as trade commodity. On that note, the most frequently used cultivation practices for coffee in Indonesia is coffee agroforestry system in private forest. However, there are still some constraints in the system development due to the traditional farmer limited knowledge of coffee cultivation practices. In this study we conducted preliminary observations on the coffee cultivation practices used by the traditional farmers to determine the steps needed to improve the coffee quality and sustainability. We study the effect of plant-spacing and shading on the growth of juvenile plant of coffee (Coffea arabica Lin.) from Sigarar utang variety. The observation was carried out in private forest of Cimarias village Sumedang district for 1 (one) month. We used the combination of 2,5m x 2,5m and 3m x 3m for plant-spacing with kayu afrika (Meisopsis eminii Engl.) as shade and without shade. This experiment used Completely Randomized Design experiment with 10 replication for each treatment, with juvenile height (cm), stem diameter (mm), and the quantity of productive primary branches as data. Then data were analyzed using Anova, Duncan’s Multiple Range Test (DMRT) 0,05, and Pearson Correlation. From the result, the best growth of juvenile plant of coffee tree was showed on 3m x 3m spacing with shade. However, the growth shown has not reached the potential of the coffee from Sigarar utang variety as supposed to in accordance with the environmental condition of the crop. This analysis also supports the prediction of low-productivity because there is positive correlation between juvenile height and the quantity of primary branches, and between stem diameter and the quantity of primary branches.

Reaction of jaboticaba trees cv. ‘Sabará’ to the species of gall forming nematodes

ABSTRACT Tropical and subtropical fruit production plays an important role in the country’s economic scenario and has been affected by root-knot nematode. The jaboticaba tree is a plant widely cultivated in Brazil, and among the problems of the crop is the root-knot nematode of the genus Meloidogyne. This study aimed to evaluate the hostability of jaboticaba tree cv. ‘Sabará’, in different inoculum concentrations of Meloidogyne incognita and Meloidogyne javanica. The inoculum used in the experiment was obtained from the roots of tomato cv. ‘Santa Cruz’. Jaboticaba trees were subjected to inoculation with concentrations of 0, 2000, 4000, and 8000 eggs + juvenile plant-1, for both species of nematodes. The plants of jaboticaba cv. ‘Sabará’ showed resistance concerning the development of M. incognita and M. javanica root-knot nematode with Reproduction Factor (RF) <1.

Susceptibility of Australian wheats to Pyrenophora tritici-repentis

The response of Australian wheats to yellow spot caused by Pyrenophora tritici-repentis has been examined under controlled conditions with a juvenile-plant screening system. About three-quarters of contemporary Australian wheats are highly susceptible to the disease and very few cultivars possess useful levels of resistance. Also, the majority of Australian wheats now undergoing final evaluation before releasing are highly susceptible to yellow spot. Modern wheats grown in Queensland and northern New South Wales are, as a group, more susceptible than those they replaced, and this may have contributed to the upsurge in yellow spot in the region. In two comparisons between ratings on juvenile plants under controlled conditions with field disease assessments and yield measures, the juvenile plant ratings and field disease assessments explained similar proportions of the variation in yield measures.

GENETIC STUDIES OF SYMBIOTIC NITROGEN FIXATION IN SPANISH CLOVER

In this genetic study of symbiotic nitrogen fixation in the tropical legume Spanish clover (Desmodium sandwicense E. Mey), it was established that the quantitative variance found within several estimates of nitrogen fixation had a genetic basis. The diallel analysis suggested that genetic variation was present and that a major portion of this variation was attributable to differences between the parents and their F1 crosses. The within-cross genetic variation was due solely to general combining ability suggesting the presence of heritable genetic variation. Genotype by environment interactions were also found to be significant. The analysis of the data from a cross between two lines suggested that the four nitrogen fixation estimates measured were highly correlated and this variation could be represented by one principal axis of variation. Significant differences among population means were found for all analyses. Plants with larger cotyledons and juvenile leaves fixed significantly more nitrogen than did plants with smaller cotyledons and juvenile leaves. This difference was attributed to juvenile plant vigor which may assist the onset of nodulation. Analysis of the population means suggested that non-heritable variation accounted for the predominant portion of the genetic variance when the nitrogen fixation estimates were unadjusted for differences due to juvenile plant vigor. However, when the nitrogen fixation estimates were adjusted for the effects of juvenile plant vigor the genetic variation was totally heritable. Such heritable variation is of agricultural importance.

A genetic study of cold resistance in wheat

SUMMARYThe variety Chinese Spring of Triticum aestivum is susceptible to cold treatment applied at the juvenile plant stage, while the variety Cappelle-Desprez shows resistance to such treatment. By cytological and backcross procedures single homologous pairs of chromosomes from Cappelle-Desprez were substituted for their homologues in Chinese Spring. Assay experiments carried out on each of the 21 possible substitution lines indicated that three chromosomes, 4D, 5D and 7A of Cappelle-Desprez were involved in the determination of cold resistance. The resistance expressed by the three substitution lines carrying these chromosomes was less than the reaction of Cappelle-Desprez to cold treatment. Also the magnitude of this resistance supported a hypothesis that the action of the three chromosomes was additive on the scale of measurement used. The possible relationships of the genes for cold resistance to the established genes controlling other developmental characters, also carried by these three chromosomes, are discussed.