Pengaruh Herbisida Metil Metsulfuron dan Kombinasinya pada Pengendalian Gulma Tanaman Tebu (Saccharum officinarum L.)

Weed control must use the right dose of herbicide so as not to leave a residual effect on cultivated plants and soil. This study ains to obtain the most appropriate dose of herbicide. Herbicide used in this study were methyl methulfuron and acetic acid combined. This study used a randomized block design (RCBD) witch 2 factors, factor A was asetic acid and factor B was methyl methulfuron and there were 12 treatment combinations with 3 replications. This research was conducted in the practicum of the Departement of Plantation Plant Cultivation, Lampung State Polytechnic. The total research plot was 36 experimentals units. The dosage levels levels of methyl methulfuron tested in this study were: 0%, 55%, 75%, and 105%. While the dose of acetic acid is: 0%, 50%, and 70%. Observations made in this study were weed vegetation analysis, weed cover percent, weed dry weight, Summed Dominance Ratio (SDR), and Community Coefficient Value (C). SDR values indicate that Panicum dicotomyflorum weed, Ricardia brasiliensis, Euphorbia heterophyla, and Cyperus rotundus are the dominant weeds. The results of this study indicate that there is no effect on the dose of methyl methulfuron herbicide, acetic acid, and interactions on methyl methulfuron herbicide and acetic acid on weed control in sugarcane fields (Saccharum officinarum L.).

Perubahan Komposisi Gulma pada Sistem Tumpangsari Padi Gogo dengan Kedelai di Lahan Pasir Pantai

Weeds can reduce upland rice yields in coastal sandy area. Density and growth of weeds can be controlled and reduced by an intercropping system between upland rice with soybeans. The study aimed to determine the weeds composition change and weeds biomass in various crop proportions of upland rice and soybean under intercropping. The research was conducted from December 2016 until March 2017, at coastal sandy soil of Samas, Bantul, Yogyakarta (8°00’03.5”S and 110°15’20.1”E). This study used a complete randomized block design (RCBD) with one factor and three replications. The treatments were crop proportions of upland rice and soybean under intercropping with 6 levels, such as 100:0 (upland rice monoculture), 80:20, 60:40, 40:60, 20:80, and 0: 100 (soybean monoculture). The results showed that there was weeds composition changes due to setting crop proportions of upland rice and soybean under intercropping at coastal sandy soil. Weed of sedges, grass, and broadleaf were found throughout the experimental plots, but varied in number and type of weeds among experimental plots. Weeds condition differed among the soybean proportion treatments &lt; 40% and ≥ 40%. The average community coefficient value was &lt;75% which was dominated by Digitaria nuda and Eragrostis tenella under soybean proportion treatments &lt; 40%, and Ludwigia parviflora and Amaranthus lividus under soybean proportion treatments ≥ 40%. The linear model was established between the increase of soybean proportion to a decrease in dry weight of weeds as Y = -0.6624X + 67.699; R2 = 0.7224).<br /><br />Keywords: crops proportion, intercropping, weeds community<br /><br />

Depth-stratified soil sampling for assessing nematode communities

This study assessed the importance of stratified soil sampling on the detection (and therefore the distribution) of nematode communities and the differentiation of ecosystems by collecting stratified soil samples at intervals of 10 cm and non-stratified samples from 0 to 30 cm in two soil management systems (no-tillage and conventional tillage) and in a native forest fragment. The nematode frequency and prominence values were obtained after extraction by successive screening operations, sugar floatation clarification and the identification of nematodes to the genus level. The nematode communities were compared two-by-two based on Sorensen’s community coefficient (CC) and the percentage similarity (PS). Relative abundances of functional guilds were subjected to a principal component analysis (PCA) and classified in dendrograms. Thirty-two edaphic nematode genera were found, and the nematode communities sampled on a non-stratified basis in the soil profile exhibited a high level of similarity because they could not be accurately characterized. Genera with low abundances were not detected. In the stratified samples, we were able to classify and group the nematodes present at different depths, mainly from 0 to 10 cm. Stratified soil sampling allowed a more accurate characterization and greater differentiation of nematode communities, identifying taxa that occurred at lower abundance levels, irrespective of frequency.

Weeds Pressuring on the Grow th and Yield of Soybean Plants By Giving an Acasia Organic Mulch

Soybean is the one of agricultural commodities that was very needed in Indonesia, neither as a human food, animal feed nor a basic material of industry. In the development of soybean plants, there were some issues that related to the agro-ecosystem during the planting and it must be overcome, the one of them was the problem of the weeds management that have not optimum yet. The purpose of this research is to examined the effectiveness of a combination of some organic mulchs towarded the weeds suppressing ability on the growth and yield of soybean. In this experiment, it was conducted the effectiveness of acasia organic mulch to suppress the growth of weeds, and also the testing of community coefficient, vegetation analysis (initial SDR value, middle and final), the weeds heavy with broad and narrow leaf types, and kinds of other teki-tekian. Plant’s growth (height, dry weight of shoots and roots). The yield components (amount of pods, amount of meaty pods, weight of 100 seeds and the yield of soybean). The experiment was conducted in a Group Randomized Plan. From the results of this study, found that the Acacia mulch is the organic mulch that effective to suppress the growth of weeds, especially in doses of 20 tons per-ha-1 of mulch Acacia.

Effects of acidity on the phytoplankton and primary productivity of selected northern Ontario lakes

The effects of acidity on primary production, species composition, and abundance of phytoplankton were investigated in six lakes in the Sudbury area of Ontario, where pH values lay between 4.05 and 7.15. Significant relationships showing an increase in water transparency and decrease in chlorophyll a concentration with declining pH were found. Percentage similarity of community (PSc) and community coefficient (CC) values were highest between lakes closest in pH, reflecting progressive changes in species composition. As the pH declined, Chlorophyta diminished in importance and the Cyanophyta became dominant. The phytoplankton diversity index (DI) remained relatively unchanged between pH values of 7.0 to 5.0 but decreased at lower values. Primary production in milligrams C metre−3 hour−1 was reduced in lakes below pH 5.5; however, as a result of the increase in depth of euphotic zone accompanying more acidic conditions, primary production in milligrams C metre−2 hour−1 remained high down to pH 4.4, below which it was drastically reduced.