Genetic mapping and QTL analysis for sugar yield-related traits in sugarcane

Genetic improvement of sugar content in sugarcane would benefit from the availability of sufficient DNA markers and a genetic map. Genetic linkage maps were constructed to identify quantitative trait loci (QTLs) for seedling brix (SB), brix (B), sucrose percent in juice (SUC), stalk number (SN), stalk length (SL), stalk diameter (SD), internodes (INT), number of green leaves (NGL), at three crop cycles across seven environments in a segregating population with 207 individuals derived from a bi-parental cross of sugarcane elite cultivars. Linkage analysis led to the construction of eight linkage groups (LGs) for Co86011 and sixteen LGs for CoH70. The combined length of the two linkage maps was 2606.77 cM distributed over 24 LGs. 31 QTLs were identified: 2 for SB, 7 for B, 6 for SUC, 4 for SN, 1 for SL, 3 for SD, 6 for INT and 2 for NGL at LOD scores ranging from 2.69 to 4.75. 7 QTLs (22 %) had stable effect across crop year and locations. Markers from parents were found to be associated with both positive and negative effect on all of the traits analyzed. The most important QTLs intervals identified in this study using single-dose marker, were qB2, qSUC2, qINT2 and qB2, qSUC2, qSL2, qINT2 located between SSR markers UGSM31₅₄₈ and UGSM31₆₄₉. These QTLs could be put into use in marker assisted breeding.     

Assessment of nitrogen losses to the environment with a Nitrogen Trading Tool (NTT)

Nitrogen (N) losses from agriculture often contribute to reduced air, groundwater, and surface water quality. The minimization of these N losses is desirable from an environmental standpoint, and a recent interest in discounted reductions of agricultural N losses that might apply to a project downstream from an agricultural area has resulted in the concept of N credits and associated N trading. To help quantify management-induced reductions in N losses at the farm field level (essential components of a Nitrogen Trading Tool), we defined a Nitrogen Trading Tool difference in reactive N losses (NTT-DNL_reac) as the comparison between a baseline and new management scenarios. We used a newly released Windows XP version of the Nitrogen Losses and Environmental Assessment Package (NLEAP) simulation model with Geographic Information System (GIS) capabilities (NLEAP-GIS) to assess no-till systems from a humid North Atlantic US site, manure management from a Midwestern US site, and irrigated cropland from an arid Western US site. The new NTT-DNL_reac can be used to identify the best scenario that shows the greatest potential to maximize field-level savings in reactive N for environmental conservation and potential N credits to trade. A positive NTT-DNL_reac means that the new N management practice increases the savings in reactive N with potential to trade these savings as N credits. A negative number means that there is no savings in reactive N and no N available to trade. The new NLEAP-GIS can be used to quickly identify the best scenario that shows the greatest potential to maximize field-level savings in reactive N for environmental conservation and earning N credits for trade.     

Polymorphism of BMPR1B,BMP15 and GDF9 fecundity genes in prolific Garole sheep

Tropical Animal Health and Production - Mutation studies in different prolific sheep breeds have shown that the transforming growth factor beta super family ligands viz. the growth differentiation...     

Vegetation structure of subtropical forest of Tabai,South Waziristan,Pakistan

Phytosociological parameters, soil and temperature conditions, importance values of species, life form, leaf size, and biomass were investigated at the village Tabai during autumn 2006. There was very little difference in air and soil temperature due to similar elevation. There was a great difference in biomass production for various stands. The original vegetation structure has been altered due to deforestation and overgrazing. There is a need for restoration of the habitat.     

Soil carbon pools of reclaimed minesoils under grass and forest landuses

Minesoils are characterized by low soil organic matter and poor soil physicochemical environment. Mine soil reclamation process has potential to restore soil fertility and sequester carbon (C) over time. Soil organic C (SOC) pool and associated soil properties were determined for reclaimed minesoils under grass and forest landuses of varied establishment year. Three grassland sites of 30, 9, and 1 years after reclamation (G30, G9, and G1) and two forest sites, 11 years after reclamation (RF) and undisturbed stand of 40 years (UF), were selected within four counties (Morgan, Muskingum, Noble, and Coshocton) of southeastern Ohio. Soil bulk density (BD) of reclaimed forest (RF) soil was significantly higher than undisturbed forest (UF) soils within 10–40 cm soil depth profile. Reclamation process increased soil pH from slightly acidic to alkaline and decreased the soil EC in both landuses. Among grassland soils, significant changes in SOC and total soil N contents were observed within 0–10 cm soil depth. SOC contents of G30 (29.7 Mg ha⁻¹) and G9 (29.5 Mg ha⁻¹) were significantly higher than G1 soils (9.11 Mg ha⁻¹). Soil N content was increased from G1 (0.95 Mg ha⁻¹) to G9 (2.00 Mg ha⁻¹) site and then the highest value was found under G30 (3.25 Mg ha⁻¹) site within 0–10 cm soil depth. UF soils had significantly higher SOC and total N content than RF soils at 0–10 and 10–20 cm soil depths. Copyright © 2009 John Wiley & Sons, Ltd.     

Tillage and drainage impact on soil quality: I. Aggregate stability, carbon and nitrogen pools

Effects of two tillage treatments, tillage (T) with chisel plough and no-till (NT), were studied under un-drained and drained soil conditions. Soil physical properties measured were bulk density (ρ_b), total porosity (ƒ_t), water stable aggregates (WSA), geometric mean diameter (GMD), mean weight diameter (MWD), organic carbon (OC) and total N concentrations in different aggregate size fractions, and total OC and N pools. The experiment was established in 1994 on a poorly drained Crosby silt loam soil (fine mixed, mesic, Aeric Ochraqualf) near Columbus, Ohio. In 2007, soil samples were collected (0–10, 10–20, and 20–30 cm) from all treatments and separated into six aggregate size classes for assessing proportions of macro (5–8, 2–5, 1–2, 0.5–1, 0.25–0.5) and micro (<0.25 mm) aggregates by wet sieving. Tillage treatments significantly (P ≤ 0.05) influenced WSA, MWD, and GMD. Higher total WSA (78.53 vs. 58.27%), GMD (0.99 vs. 0.68 mm), and MWD (2.23 vs. 0.99 mm) were observed for 0–10 cm depth for NT than T treatments. Relative proportion of macro-aggregates (>0.25-mm) was also more in NT than T treatment for un-drained plots. Conversely, micro-aggregates (<0.25-mm) were more in T plots for both drained and un-drained treatments. The WSA, MWD and GMD decreased with increase in soil depth. The OC concentration was significantly higher (P ≤ 0.05) in NT for un-drained (P ≤ 0.01) treatment for all soil depths. Within macro-aggregates, the maximum OC concentrations of 1.91 and 1.75 g kg⁻¹ in 1–2 mm size fraction were observed in NT for un-drained and drained treatments, respectively. Tillage treatments significantly (P < 0.01) affected bulk density (ρ_b), and total porosity (f_t) for all soil depths, whereas tillage × drainage interaction was significant (P < 0.01) for 10–20 and 20–30 cm depths. Soil ρ_b was negatively correlated (r = −0.47; n = 12) with OC concentration. Tillage treatments significantly affected (P ≤ 0.05) OC pools at 10–20 cm depth; whereas drainage, and tillage × drainage significantly (P ≤ 0.05) influenced OC pools for 0–10 cm soil layer. The OC pool in 0–10 cm layer was 31.8 Mg ha⁻¹ for NT compared with 25.9 Mg kg⁻¹ for T for un-drained treatment. In comparison, the OC pool was 23.1 Mg ha⁻¹ for NT compared with 25.2 Mg ha⁻¹ for T for the drained plots. In general, the OC pool was higher in NT system, coupled with un-drained treatment than in drained T plots. The data indicate the importance of NT in improving the OC pool.     

Chemical stabilization of organic carbon pools in particle size fractions in no-till and meadow soils

The knowledge about the relevance of physical and chemical fractionation methods to soil organic carbon (SOC) stabilization mechanisms is fragmentary but needed to manage the SOC pool. Therefore, our objective was to compare the C contents of the particle size fractions coarse and fine sand, silt, and clay of the two uppermost horizons of a soil under three different management systems (meadow; no-till corn, NT; no-till corn with manure, NTm). The mineral composition was dominated by silt (48–60%). However, coarse sand and clay showed the highest enrichment of C compared to the bulk soil. In spite of an enrichment factor below 1, the high proportion of silt made this fraction the main C store. In the upper 30 cm, this fraction amounted to 27.1 Mg C ha⁻¹ in NTm and progressively less in NT (15.5 Mg C ha⁻¹), and meadow (14.9 Mg C ha⁻¹), representing 44%, 39%, and 39% of the total SOC pool, respectively. The C in the isolated particle size fractions was further investigated by an oxidizing treatment with Na₂S₂O₈ and a treatment with HF to solubilize the mineral phases. The pools of oxidizable C were comparable among particle size fractions and pedons, as indicated by Na₂S₂O₈ treatment. The pools of C preferentially associated with soil minerals were also comparable among pedons, as indicated by HF treatment. However, NTm stored the largest pool (12.6 Mg ha⁻¹) of mineral-associated C in 0–30 cm depth. The silt-associated and mineral-bound SOC pool in NTm was greater compared to NT due to increased organic matter (OM) input. Thus, the silt particle size fraction at the North Appalachian Experimental Watershed (NAEW) has the potential for SOC sequestration by stabilizing OM inputs. Mineralogical and molecular level analyses on a larger set of fractions obtained from entire rooted soil profiles are required, however, to compare the SOC sequestration capacity of the land uses.     

Soil enzymatic activity as affected by long term application of farm yard manure and mineral fertilizer under a rainfed soybean–wheat system in N-W Himalaya

Long-term experimental sites are expected to provide important information regarding soil properties as affected by management practices. This study was designed to examine the effects of continuous fertilization, and manuring on the activities of enzymes involved in mineralization of C, N, and P on a long term (33 years) field trial under sub-temperate conditions in India. Treatments at the site included application of recommended doses of nitrogen and phosphorus (NP), nitrogen and potassium (NK), nitrogen, phosphorus and potassium (NPK), farmyard manure (FYM) with N (N + FYM), FYM with NPK (NPK + FYM) and un-amended control (C). The study was done under rainfed soybean–wheat rotation. Manure application increased soil carbohydrate, dehydrogenase, acid and alkaline phosphatases, cellulase, and protease activity significantly. Urease activity was not influenced by the manure treatment and the activity was highest in controls. Both acid and alkaline phosphatase activities were negatively influenced by chemical fertilizer treatment. Almost all the enzymes studied were significantly correlated with soil C content. The results suggest that application of FYM directly or indirectly influences the enzyme activity and it in turn regulates nutrient transformation.     

Carbon sequestration in soils of central Asia

Problems of frequent drought stress, low soil organic carbon (SOC) concentration, low aggregation, susceptibility to compaction, salinization and accelerated soil erosion in dry regions are accentuated by removal of crop residues, mechanical methods of seedbed preparation, summer clean fallowing and overgrazing, and excessive irrigation. The attendant soil degradation and desertification lead to depletion of SOC, decline in biomass production, eutrophication/pollution of waters and emission of greenhouse gases. Adoption of conservation agriculture, based on the use of crop residue mulch and no till farming, can conserve water, reduce soil erosion, improve soil structure, enhance SOC concentration, and reduce the rate of enrichment of atmospheric CO₂. The rate of SOC sequestration with conversion to conservation agriculture, elimination of summer fallowing and growing forages/cover crops may be 100 to 200 kg ha⁻¹ y⁻¹ in coarse‐textured soils of semiarid regions and 150 to 300 kg ha⁻¹ y⁻¹ in heavy‐textured soils of the subhumid regions. The potential of soil C sequestration in central Asia is 10 to 22 Tg C y⁻¹ (16±8 Tg C y⁻¹) for about 50 years, and it represents 20 per cent of the CO₂ emissions by fossil fuel combustion. Copyright © 2004 John Wiley & Sons, Ltd.