Pengaruh peningkatan suhu pada fase pembentukan umbi tanaman kentang (Solanum tuberosum) cv. Granola

Kentang (Solanum tuberosum) merupakan salah satu bahan makanan yang penting di dunia. Budidaya komoditas ini umumnya berada di dataran tinggi dengan suhu yang rendah. Jumlah lahan pertanian di dataran tinggi semakin kecil disebabkan antara lain karena alih fungsi lahan. Penanaman kentang di dataran yang lebih rendah menjadi kendala karena adanya peningkatan suhu. Penelitian ini dirancang untuk mengetahui pengaruh ketinggian tempat dan perubahan suhu terhadap tanaman kentang pada fase pembentukan umbi. Tanaman kontrol ditanam pada ketinggian 2921 meter diatas permukaan laut (m dpl) dengan suhu siang/malam (190C/120C). Setelah fase pembentukan umbi, sebagian tanaman dipindah ke daerah dengan ketinggian 115 m dpl dengan suhu siang/malam (300C/240C). Perubahan ketinggian tempat dengan suhu yang berbeda mengakibatkan shade avoidance, perubahan akumulasi biomasa pada batang tanaman dan penurunan hasil panen. Hal ini disebabkan karena penurunan hasil fotosintesa, sukrosa, serta kadar klorofil yang disebabkan oleh faktor genetik dan metabolisme enzim. Oleh karena untuk mendukung permintaan komoditas kentang yang semakin meningkat, pemuliaan tanaman kentang tahan terhadap cekaman suhu diperlukan untuk memperluas area penanaman kentang di dataran menengah maupun dataran rendah.ABSTRACTPotato (Solanum tuberosum) is one of the important staple foods in the world. This plant is mostly cultivated in high-altitude regions with low temperatures. As the number of lands for potato cultivation is getting smaller due to land conversion. Potato cultivation in low-altitude regions with high temperatures yields low productivity. This study was designed to determine the effect of altitude and temperature changes on potato plants in the tuber formation phase. Control plants were planted in an area with an altitude of 2921 meters above sea level (m asl), with day/night temperatures (190C/120C). After the tuber formation phase, some plants were transferred to areas with an altitude of 115 m above sea level and day/night temperatures (300C/240C). Change in altitude with different temperatures resulted in shade avoidance, changes in the accumulation of biomass on plant stems, and yield reduction. This is due to decreasing sucrose content as photosynthesis assimilates, and chlorophyll content due to genetic factors and enzyme metabolism. Therefore, to support the increasing demand for potato commodities, breeding potato plants resistant to heat stress is needed to expand the potato planting area in middle or low altitudes.

Euphorbia tirucalli L.-comprehensive characterization of a drought tolerant plant with a potential as biofuel source.

Of late, decrease in mineral oil supplies has stimulated research on use of biomass as an alternative energy source. Climate change has brought problems such as increased drought and erratic rains. This, together with a rise in land degeneration problems with concomitant loss in soil fertility has inspired the scientific world to look for alternative bio-energy species. Euphorbia tirucalli L., a tree with C3/CAM metabolism in leaves/stem, can be cultivated on marginal, arid land and could be a good alternative source of biofuel. We analyzed a broad variety of E. tirucalli plants collected from different countries for their genetic diversity using AFLP. Physiological responses to induced drought stress were determined in a number of genotypes by monitoring growth parameters and influence on photosynthesis. For future breeding of economically interesting genotypes, rubber content and biogas production were quantified. Cluster analysis shows that the studied genotypes are divided into two groups, African and mostly non-African genotypes. Different genotypes respond significantly different to various levels of water. Malate measurement indicates that there is induction of CAM in leaves following drought stress. Rubber content varies strongly between genotypes. An investigation of the biogas production capacities of six E. tirucalli genotypes reveals biogas yields higher than from rapeseed but lower than maize silage

Specific biogas production (L biogas kg⁻¹ ODM) and gas composition in the biogas produced.

<p>n.a., not analyzed. In case standard deviations could be calculated, they were always less than 10%.</p

Effect of water limitation on quantum effciency during 8 weeks drought stress treatment.

<p>n = 5 (A) Morocco leaves, (B) Morocco stem, (C) Senegal leaves (D) Senegal stem, (•) VWC 25%, (○) VWC 15%, (▾) VWC 10% and (Δ) VWC 5%, n = 5. Vertical error bars denote the standard error of mean (SEM). Stars above the point denote significant difference between VWC in each week treatment following the Tukey procedure (<i>p</i><0.05).</p