旱地玉米等雨晚播技术的农业气候原理

应用气候生产潜力理论,定量考虑了光、温、水3种气候要素对玉米生长发育的影响,组建了利用气候资料计算玉米潜在产量的理论模式,算出旱地玉米的最佳,播种期中熟种在5月中下旬,早熟种在6月上中旬,与分期播种试验的结果相一致.论证了等雨晚播技术是符合气候规律的防旱增产有效措施.应用山地气候变化规律,提出玉米等雨晚播的“海拔—播期—品种搭配”配套技术.     

Relay-Intercropping of Stylosanthes guianensis in Rainfed Lowland Rice Ecosystem in Northeast Thailand

We evaluated the usefulness of the Stylosanthes guianensis (stylo)- rice relay-intercropping system for increasing agricultural productivity in Northeast Thailand. Although large production variability was observed, the relay-intercropping system produced an average of 350 g m-² stylo dry matter during the dry season under non-irrigated and non-fertilized conditions in the experimental fields at the Ubon Rice Research Center. Utilization of the stylo production as green manure increased rice yield, but only slightly. The relay-intercropping also slightly improved soil chemical properties, but not significantly. The trial of the relay-intercropping in farmer’s fields produced a maximum of 367 g m-² stylo dry matter. Since the stylo production did not decrease the subsequent rice production, the rice-stylo relay-intercropping system is worth considering as one way to utilize the paddy fields during the dry season in Northeast Thailand.     

APPLICATION OF FUZZY FLEXIBLE CLASSIFICATION IN RAINFED AGRICULTURAL DEMARCATION

<正> The paper, by the flexible classification in fuzzy mathematics, uses precipitation, meantemperature, sunshine duration, dry index (namely evaporation to precipitation in the corre-sponding period) and cumulative temperature≥10°C between March to September asclassifying indices, and classifies the whole region of Ningxia. We have obtained resultswhich are basically in accordance with the previous divisions, but has some differences.     

The effect of system innovations on water productivity in subsistence rainfed agricultural systems in semi-arid Tanzania

Rainfed subsistence farming systems in sub-Saharan Africa generally obtain low crop yields as a result of highly erratic rainfall seasons. This paper presents results of research conducted to test the effects of improvements in farming techniques for subsistence rainfed systems. The research was carried out in the Makanya catchment of northern Tanzania where rainfall of less than 600 mm a⁻¹ and spread over two agricultural seasons per year is clearly insufficient to support staple food crops under the present farming systems in the area. The research sought to prove that, with improved efficiency in tillage techniques, grain yields can improve even under the existing challenging hydro-climatic conditions. The research tested farming system innovations (SIs) at four sites located within a spatial distance of 10 km where a combination of runoff diversion (RD), on-site rain water harvesting (WH) and conservation tillage (CT) were compared against the traditional farming methods of hand-hoeing under strict rainfed conditions (Control). For RD, runoff generated from natural storms was directed into infiltration pits dug along the contour with the excavated soil deposited upward of the trenches (fanya juus). The impact of these techniques on maize yields under different SIs was investigated.The results showed that the innovations resulted in increased maize grain yields of up to 4.8 t ha⁻¹ compared against current averages of less than 1 t ha⁻¹. The average productivity of the available water over four seasons was calculated to range between 0.35 and 0.51 kg m⁻³. For the SIs that were tested, the distribution of yields within a cultivated strip showed variations with better yields obtained on the down slope side of the cultivated strip where ponding effects resulted in higher water availability for infiltration and storage. However, due to the large seasonal climate variability, statistical analysis did not show significant differences in the yields (p < 0.05) between different cultivation techniques.The study showed that there is scope to improve grain yields with the little available rainfall through the adoption of techniques which promote water availability and retention within the field. The re-partitioning of water within the field creates mitigation measures against the impact of dry spells and allows alternative cropping in addition to the traditional maize cultivated in the rainfall seasons.     

Comparative analysis of farmers engaged in participatory research to cope with climate change versus non-participants in Northeast Thailand

ABSTRACT

To assess the extent of improvement of rainfed rice production by using a participatory approach, we compared research project participants and non-participants (total of 206 rice-growing households) with regard to yield variability and their perspective on climate change at seven sites in Northeast Thailand. The participants were characterized by membership in local groups, an active learning attitude, and confidence in their farming. Compared to non-participants, the participants produced crops with higher yield and had more knowledge about the Intergovernmental Panel on Climate Change (IPCC) message and advanced farming technologies. Both groups had similar reactions to past climatic damage experiences, but the participants tended to have a more positive attitude about adaptation to climate change and mitigation by refraining from residual straw burning than the non-participants. The farmers’ attitude about adaptation to climate change was positively associated with their active learning and close relationship with researchers. There was a large yield gap between the bottom 10 percentile farmers (0.63 t/ha) and the top 10 percentile farmers (4.05 t/ha), with an average yield of 2.18 t/ha. Yield was associated with the level of market orientation, with the market-oriented farmers attaining higher yield, including yield from broadcast seeding (2.71 t/ha), than the subsistence farmers (1.66 t/ha). Our findings suggest that technical improvement of rice production in the region by using the participatory approach could be enhanced by selecting participants who are linked with local groups, tend to be market orientated, and are willing to learn with researchers.     

Growth and Yield of New Rice for Africa (NERICAs) under Different Ecosystems and Nitrogen Levels

Abstract

Scarcity of water and N fertilizer are major constraints to rice production, particularly in developing countries where rainfed upland condition dominates. Improvement of genetic adaptability to inadequate water and N fertilizer is one option to maintain productivity in these regions. NERICAs are expected to yield higher under low input conditions, but growth and yield responses of the cultivars to different ecosystems and N levels remain unknown. The objectives of this study were to characterize the growth and yield performance of NERICAs, in comparison with selected Japanese rice cultivars. The two NERICAs (NERICA 1 and NERICA 5), two Japanese upland cultivars (Toyohatamochi and Yumenohatamochi), and a Japanese lowland cultivar Hitomebore were grown under two ecosystems (irrigated lowland (IL) and rainfed upland (RU)) with two N levels (high (H) and low (L)) for two years. The cultivar difference in the aboveground dry weight and grain yield was the largest in the in RU × L plot, where the values of NERICAs were similar to those in the other plots, but the values of other cultivars were substantially reduced. Regardless of cultivar, N contents of the plants at maturity correlated significantly with the aboveground dry weight at maturity, spikelet number and grain yield per area. These results indicate that NERICAs, compared with the selected Japanese upland cultivars that were bred for drought tolerance, have a higher ability to absorb N under upland conditions, which may contribute to higher biomass production and sink formation, resulting in increased gain yield.     

Tolerance of longer-term partial stagnant flooding is independent of the SUB1 locus in rice

Longer-term partial stagnant flooding, particularly when it occurs following transient complete submergence causes severe damage to modern rice varieties. Progress was made in developing varieties tolerant of complete submergence through transfer of the Submergence-1 (SUB1) gene into popular varieties. However, SUB1 may not be effective under partial stagnant flooding (SF), as the new varieties may not elongate and continue growth when fully or partially submerged because of the SUB1-mediated suppression of elongation. We tested a set of rice genotypes, including a pair of near-isogenic lines (NILs), Swarna and Swarna-Sub1, under either SF or SF following complete submergence of 12 d. Swarna-Sub1 had higher survival and yield than Swarna following 12 d of submergence, but survival and grain yield of all lines decreased substantially when SF of 15-30 cm followed complete submergence, with the sensitive lines experiencing greater reductions in growth and yield. This suggests the importance of combining SUB1 with tolerance of SF in areas where both stresses are expected during the season. Swarna and Swarna-Sub1 are more sensitive to long-term partial SF than IR49830 and IR42 because of their short stature, and Swarna-Sub1 showed slightly higher reduction in tillering than did Swarna when subjected to deeper SF alone, possibly because of further inhibition of elongation by SUB1 if induced in submerged tissue. The results suggest that tolerance of these genotypes to SF depends less on SUB1 introgression and more so on the genetic background of the recipient genotype, with better performance of the genotypes that are inherently taller, such as IR42 and IR49830. The SUB1 donor landrace FR13A and its derivative breeding line IR49830 had better survival and relatively less reduction in grain yield under SF following complete submergence and under longer-term partial SF, indicating that these genotypes may have genes other than SUB1 for submergence and SF tolerance. For better adaptation to prolonged SF, SUB1 should be introgressed into genotypes that tolerate partial SF through better tillering ability and taller shoots, because SUB1 may not be effective in shorter genotypes, as it promotes survival of submerged plants by hindering shoot elongation to conserve energy reserves. Varieties combining tolerance of prolonged SF with SUB1 will have broader adaptation in flood-prone areas and greater impacts on yield stability.     

半湿润偏旱区沟垄覆盖种植对冬小麦产量及水分利用效率的影响

为探索半湿润偏旱区沟垄集雨种植模式下冬小麦田土壤蓄水保墒和节水增产效果, 于2007-2010年连续3个小麦生长季在渭北旱塬旱农试验站, 研究了不同沟垄集雨种植模式对土壤水分、冬小麦产量和水分利用效率的影响。设置3个沟垄集雨处理, 分别是垄上覆盖地膜+沟内不覆盖(P1)、沟内覆盖小麦秸秆(P2)、沟内覆盖液体地膜(P3)处理, 以传统平作(CK)为对照。P1、P2和P3处理显著提高冬小麦生育前期0~20 cm和20~100 cm的土壤贮水量, 其中以P2处理蓄水保墒效果最显著, P3处理由于液态地膜的降解, 仅在小麦生长前期有一定的蓄水保墒作用, 在小麦的生长后期与P1处理无显著差异;各沟垄集雨处理100~200 cm土壤贮水量与CK无差异。P2处理对冬小麦平均株高和生物量影响最大, 3年平均株高和生物量分别较对照提高26.7%和60.3%。以P2处理增产效果最显著, 3年平均产量和水分利用效率分别较CK对照提高39.3%和35.6%;且P1和P3之间无显著差异。因此, 垄覆地膜、沟覆秸秆的二元沟垄集雨覆盖种植模式能显著提高冬小麦产量和水分利用效率, 适宜在半湿润偏旱区冬小麦生产中应用。     

Association between climate indices,aridity index,and rainfed crop yield in northeast of Iran

Agricultural drought occurs when there is a deficit in soil water supply to crops. Severe drought limits crop water availability and reduces yield. Rainfed crop production is very vulnerable to drought conditions and farmers in northeast of Iran who heavily depend on their rainfed cereals production usually suffer from drought occurrence. Based on history, any severe drought resulted in severe financial problems and forced the affected farmers to move to cities in search of alternative jobs. Any possibility to enable the farmers to mitigate or adapt to drought is highly required. In this study, the relationship between aridity index (AI) and detrended crop yield (1985–2005) of selected crops (wheat and barley) and the influence of three climate indices (AO, NAO and NINO-3.4) were assessed for Khorasan province in northeast of Iran. All associations were assessed at annual, seasonal (wet and dry seasons) and monthly scale considering both concurrent and lag correlations (1-year and 2-year lag). Our results indicated a significant correlation (P < 0.05) between the AI and crops yield mostly in central Khorasan province. Our study also showed that correlation coefficient between AI and barley yield was stronger than AI and wheat yield across all study locations. Seasonal (wet) AI showed significant correlation with crops yield. These results demonstrated that, in some areas of Khorasan, drought is one of the key causes of interannual yield variability. We also observed a significant association between NAO and NINO-3.4 with AI. Precipitation is one of the components of AI, so AI response to NAO and NINO-3.4 can be related to the observed association between this index and precipitation. It seems that these indices could be useful tools to monitor drought patterns and subsequent yield variability in some regions of Khorasan province.     

Nutrient management for rainfed lowland rice in northeast Thailand

Average grain yields of rainfed lowland rice in northeast Thailand are the lowest in the region, and they barely changed in the past decade. Improved fertilizer management is one of the few options to enhance cropping system productivity but related results from previous studies were often disappointing and sometimes contradictory, possibly due to the large variability of soil and water resources. Therefore, the objectives of this study were to develop a site-specific nutrient management approach, and to propose a related decision tool for farmers. For this purpose, we conducted on-farm experiments in Kumpa-Oong Village, Roi Et Province, during the 2003–2005 cropping seasons. Tested fertilizer treatments were designed based on topographic field position. A comparison of soil characteristics between lower and upper fields revealed significantly higher soil fertility for lower fields (higher pH, TOC, TSN, CEC, clay, and silt content; lower sand content). Across seasons and treatments, grain yields were higher in the valley bottom (VB; 2.82 t ha⁻¹) than on upper and middle terraces (UMT; 1.68 t ha⁻¹). In all seasons, significant fertilizer treatment effects were detected only in UMT fields. But the comparison of treatment effects in individual fields and in both toposequence positions showed that the limited average fertilizer response was mainly caused by low or even negative responses in fields with a higher control yield, i.e., with higher indigenous nutrient supply. A missing or even negative fertilizer response occurred at lower control yields in UMT fields, most probably because attainable yields in these fields were lower as a result of limited water resources. Thus, site-specific fertilizer recommendations need to take toposequence and the field-specific indigenous nutrient supply into account. Based on these results, we proposed a decision tool that helps farmers to choose the most adequate fertilizer treatment for their fields, based on their knowledge of specific field characteristics. On-farm testing of the proposed decision tool is the next step to show whether this approach is acceptable to farmers and can contribute to higher resource-use efficiency and system productivity.