Effects of rice or wheat residue retention on the quality of milled japonica rice in a rice–wheat rotation system in China

In rice–wheat rotation systems, crop straw is usually retained in the field at land preparation in every, or every other, season. We conducted a 3-year-6-season experiment in the middle–lower Yangtze River Valley to compare the grain qualities of rice under straw retained after single or double seasons per year. Four treatments were designed as: both wheat and rice straw retained(WR), only rice straw retained(R), only wheat straw retained(W), and no straw retained(CK). The varieties were Yangmai 16 wheat and Wuyunjing 23 japonica rice. The results showed contrasting effects of W and R on rice quality. Amylopectin content, peak viscosity, cool viscosity, and breakdown viscosity of rice grain were significantly increased in W compared to the CK, whereas gelatinization temperature,setback viscosity, and protein content significantly decreased. In addition, the effect of WR on rice grain quality was similar to that of W, although soil fertility was enhanced in WR due to straw being retained in two cycles. The differences in protein and starch contents among the treatments might result from soil nitrogen supply. These results indicate that wheat straw retained in the field is more important for high rice quality than rice straw return, and straw from both seasons is recommended for positive effects on soil fertility.     

Fantastic yields in the system of rice intensification: fact or fallacy?

The combination of natural resources, genes, weather and management systems largely determines maximum crop yields. Recently, one of those elements was portrayed as the key to releasing hitherto unrecognized, but significant, untapped growth potential in rice. That element, the system of rice intensification (SRI), is an unconventional management system developed in Madagascar, where it was reported to increase rice yields to ‘fantastic’ levels. To investigate the general potency of the SRI, we conducted experiments in three locations in China comparing yields in conventional and SRI management systems. In addition, we used a theoretical model to predict maximum yields and compared those with reported yields for various locations, including China and Madagascar. Our results imply that the SRI has no inherent advantage over the conventional system and that the original reports of extraordinary high yields are likely to be the consequence of error.     

Limits to Growth or Growth to the Limits? Trends and Projections for Potatoes in China and Their Implications for Industry

While output for potatoes in China averaged nearly 73 million metric tonnes in 2008–2010, the trends for production, area, and yield have been far more volatile than suggested in earlier studies. A new set of estimated growth rates for potato production in China during the last five decades based on FAO times series data found that periods of rapid expansion were then followed by ones of stagnation and decline. Although increases in potato output have been impressive, China’s share of both regional and global production has declined in recent years as a result. This paper analyses these and other dimensions to the evolution of potato production in China during the last half century by synthesizing previous research before reassessing alternative future projections, highlighting opportunities for industry, and identifying some key topics for future research.     

Can the cropping schedule of rice be adapted to changing climate? A case study in cool areas of northern Japan

Adaptation of cropping schedules in response to climate change is essential for increasing rice productivity. In the present study, we analyzed yield, cropping schedule and cultivar characteristics records from 1958 to 2007 in a case study of four prefectures in northern Japan, where low temperatures can severely limit rice growth. Grain yield in all prefectures increased over time, with a higher increase from 1958 to 1982 (2.4 g m⁻² y⁻¹) than from 1983 to 2007 (1.0 g m⁻² y⁻¹). The transplanting date became 0.07–0.91 days y⁻¹ earlier before 1983, but did not appear to change thereafter. The growing period duration from transplanting to harvesting increased over time, especially during the first 25 years. We observed a significant correlation between grain yield and transplanting date before 1983. The length of the potential growing period, defined as the period from the earliest potential date for transplanting and the latest potential date for harvesting, increased over time in all four prefectures. The gap between the actual growing period and the potential growing period increased after 1983. The safe reproductive period, which is defined as the duration within which rice can escape cold damage during its reproductive stage, did not appear to change over time. Based on these results, we discuss future cropping schedules capable of increasing rice productivity under a changing climate in the future.     

Higher crop performance of rice hybrids than of elite inbreds in the tropics: 2. Does sink regulation,rather than sink size,play a major role?

Higher harvest index, widely reported as a main trait supporting major improvements in rice yield potential, also supports the higher performance of hybrids over inbreds. Although higher sink size is generally claimed for being the driver of higher grain filling in hybrid rice, it is relevant to question whether efficient sink regulation, that is timing and magnitude of the successive sink activities over crop growth from early stage, plays a role in supporting higher harvest index and is a key feature ensuring higher performance of hybrid rice. The partitioning coefficient (PC), as the increase in dry matter of one single organ over that of shoot, was calculated over short and successive periods to quantify the dynamics of dry matter partitioning. Four hybrid and four inbred genotypes of similar crop duration were grown under the same cropping management on the IRRI farm during a wet and a dry seasons. While PC to blade and sheath was similar for both plant types in both seasons at the early stage, PC to culm of hybrids was higher than that of inbreds, and PC to blade was lower, in the late vegetative and early reproductive phases. During the late reproductive phase, PC to panicle of hybrids was higher than that of inbreds, and PC to culm was lower whereas culm elongation was similar for both plant types. During grain filling, PC to culm was significantly more negative with hybrids which indicated stronger remobilization with hybrids. Specific culm length before anthesis, as low as 40 cm g⁻¹, accounted for storage ability, and at maturity, as high as 130 cm g⁻¹, for remobilization ability. Sink strength index, as a better indicator of dry matter partitioning efficiency than harvest index, and unfilled grain size, as an indicator of assimilate wastage, were suggested as key indices to account for the better sink regulation in hybrid rice and to improve screening protocols for increasing yield potential and tolerance to lodging.     

Decreasing input–output balance by reducing chemical fertilizer input without yield loss in intensive cropping system in the Coastal Area of southeast Lake Dianchi,Yunnan Province,China

Overuse of chemical fertilizer and/or manure in agriculture is a principal factor in water eutrophication in China. Our previous study indicated that reducing chemical fertilizer input effectively decreased the soil nitrogen, phosphorus, and potassium in an intensive vegetable cropping system in the coastal area of southeast Lake Dianchi, China. This study aimed to decrease the input–output balance, namely the nutrient balance between input of fertilizer and output through vegetable harvesting, by reducing chemical fertilizer application without yield loss. A pot experiment was performed using chemical fertilizer with different amounts of N, P, and K on soils from six vegetable fields’ representative of the study area. High nitrate concentration in soils 2, 3, and 6 resulted in high N absorption from soil, and low N absorption from chemical fertilizer. Moreover, the responses of dry matter production to N absorbed from chemical fertilizer were less sensitive in soils 2, 3, and 6 than those in the other soils. Accordingly, reducing N input of chemical fertilizer did not decrease total N absorption or dry matter production, which should be the reason why reducing N input of chemical fertilizer did not reduce dry matter production in soils 2, 3, and 6. In the cases of soils 1, 4, and 5, reducing N input of chemical fertilizer reduced dry matter production, owing to lower levels of soil nitrate. This study should be helpful for reducing nutrient surplus from chemical fertilizer in the coastal area of southeast Lake Dianchi and other eutrophic agricultural areas in China.     

Increased productivity through integrated soil fertility management in cassava–legume intercropping systems in the highlands of Sud-Kivu,DR Congo

Smallholder farmers in sub-Saharan Africa are confronted by low productivity and limited investment capacity in nutrient inputs. Integrated soil fertility management (ISFM) aims at increased productivity through the combined use of improved germplasm, judicious fertilizer application and organic matter management, adapted to the local farming conditions. We hypothesize that the application of these different ISFM components can result in significant increases in productivity and economic benefits of cassava–legume intercropping systems. Participatory demonstration trials were conducted in the highlands of Sud-Kivu, DR Congo with 12 farmer groups during 3 seasons. Treatments included the farmers’ common practice (local common bean and cassava varieties, seed broadcast and manure addition) and sequentially added ISFM components: improved bean and cassava germplasm, modified crop arrangements, compound NPK fertilizer application and alternative legume species (groundnut or soybean). The use of improved germplasm did not result in yield increases without simultaneous implementation of other ISFM components. Modifying the crop arrangement by planting cassava at 2 m between rows and 0.5 m within the row, intercropped with four legume lines, increased bean yields during the first season and permits a second bean intercrop, which can increase total legume production by up to 1 t ha⁻¹ and result in an additional revenue of almost 1000 USD ha⁻¹. Crop arrangement or a second legume intercrop did not affect cassava storage root yields. Fertilizer application increased both legume and cassava yield, and net revenue by 400–700 USD ha⁻¹ with a marginal rate of return of 1.6–2.7. Replacing the common bean intercrop by groundnut increased net revenue by 200–400 USD ha⁻¹ partly because of the higher market value of the grains, but mostly due to a positive effect on cassava storage root yield. Soybean affected cassava yields negatively because of its high biomass production and long maturity period; modifications are needed to integrate a soybean intercrop into the system. The findings demonstrate the large potential of ISFM to increase productivity in cassava–legume systems in the Central-African highlands. Benefits were, however, not observed in all study sites. In poor soils, productivity increases were variable or absent, and soil amendments are required. A better understanding of the conditions under which positive effects occur can enable better targeting and local adaptation of the technologies.     

Characteristics of growth and quality,and factors contributing to high yield in newly developed rice variety ‘Akidawara’

The newly developed rice variety ‘Akidawara’ (AKI) combines the traits of high yield and highly palatability, and its cultivation is expected to spread. We examined characteristics of growth and quality, and factors contributing to high yield in AKI by comparing with ‘Nipponbare’ (NIP). Grain yield for AKI were 703 g m^?2 (9% more than NIP) and 781 g m^?2 (14% more than NIP) under the standard and heavy fertilizer regimes. It was also suggested that increase in the sink capacity was the key contributors to the high yield in AKI resulting from a conspicuous increase in the number of spikelets, which is likely due to introgression of the high-yielding variety allele. Furthermore, AKI achieved the similar degree of sink filling in spite of its larger sink capacity. In this point, panicle dry weight increase during ripening (ΔP) was significantly higher for AKI than for NIP despite the fact that no differences in shoot dry weight increase were observed between varieties. The greater ΔP in AKI might be derived from its larger sink capacity and the difference between varieties involves the translocation of nonstructural carbohydrate. In the grain quality, the reduction in perfect grain ratio was negligible and regarded as a small trade-off for AKI’s 14% increase in yield, and grain protein content increased to a lesser degree in AKI at the same yield level. These results suggest that over 700 g m^?2 high yield can be achieved with relative high grain quality and lower protein content in AKI.     

Relationship between PSII-D1-protein,xanthophyll cycle and the differences in capacities related to photodamage-resistance of indica and japonica subspecies of rice（O.sativa L.）

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Does the Relief of Glucose Toxicity Act As a Mediator in Proliferative Actions of Vanadium on Pancreatic Islet Beta Cells in Streptozocin Diabetic Rats?

Background: Data shows vanadium protects pancreatic beta cells (BC) from diabetic animals. Whether this effect is direct or through the relief of glucose toxicity is not clear. This study evaluated the potential effect of oral vanadyl sulfate (vanadium) on glycemic status and pancreatic BC of normal and diabetic rats. Methods: Rats were divided into five groups of normal and diabetic. Diabetes was induced with streptozocin (40 mg/kg, i.v.). Normal rats used water (CN) or vanadium (1 mg/ml VOSO₄, VTN). Diabetic rats used water (CD), water plus daily neutral protamine Hagedorn insulin injection (80 U/kg, ITD) or vanadium (VTD). Blood samples were taken for blood glucose (BG, mg/dL) and insulin (ng/dL) measurements. After two months, the pancreata of sacrificed rats were prepared for islet staining. Results: Pre-treated normal BG was 88 ± 2, and diabetic BG was 395 ± 9. The final BG in CD, VTD, and ITD was 509 ± 22, 138 ± 14, and 141 ± 14, respectively. Insulin in VTN (0.75 ± 0.01) and VTD (0.78 ± 0.01) was similar, higher than CD (0.51 ± 0.07) but lower than CN (2.51 ± 0.02). VTN islets compared to CN had larger size and denser central core insulin immunoreactivity with plentiful BC. CD and ITD islets were atrophied and had scattered insulin immunoreactivity spots and low BC mass. VTD islets were almost similar to CN. Conclusion: Besides insulin-like activity, vanadium protected pancreatic islet BC, and the relief of glucose toxicity happening with vanadium had a little role in this action. Key Words: Vanadium, Rats, Diabetes, Protection, Beta cells     

Indirect changes associated with a selection program for increased seed-yield in wild species of Lesquerella (Brassicaceae): Are we developing a phenotype opposite to the expected ideotype?

Seed-yield stability, frequently associated with drought-tolerance strategies, is one of the main breeding objectives for the development of crops for semi-arid mediterranean-type environments. Since breeding of new industrial crops targeted for arid lands is not appreciably different from that of traditional crops, higher yield is achieved by increased harvest-index, at the cost of losing traits associated with drought-tolerance and reduced seed-yield stability. Using Lesquerella as a model we compared selected and unselected accessions of annual (L. gracilis and L. angustifolia) and perennial (L. pinetorum and L. mendocina) genotypes grown in field experiments in Patagonia, Argentina. Our objective was to assess the effects of breeding for increased seed-yield on traits related to the main characteristics that define the most common ideotype for mediterranean-type environments: early vigor, conservative growth strategy post-anthesis and reserves storage. Our specific question was: Have any of the attributes associated with seed-yield stability been indirectly selected during the domestication process? Our results show that these characteristics were reduced or lost, in selected lines compared to their wild relatives. Early vigor was lower in selected accessions and was associated mainly with reduced relative growth rate and CO₂ assimilation. During the reproductive period the growth strategy was changed by selection towards a non-conservative and more acquisitive resource use strategy. Traits associated with this strategy were linked to higher water use efficiency and growth capacity (higher CO₂ assimilation rate, specific leaf area, and leaf allocation), but also with loss of structural adaptation to low resource environments (i.e. low specific leaf area), an increase in nutrient and water demands, and reduced nutrient use efficiency. Carbohydrates accumulation pre-anthesis was lower in selected accessions of all four species, and also, just in perennials we found lower reserves storage post-anthesis. These changes in the pattern of carbohydrates accumulation could be associated to lower seed-yield stability due to the loss of buffer capacity linked with the use of pre-anthesis reserves for seed filling. On the other hand, in perennial species lower reserves storage after seed harvest could reduce plant longevity and survival. We conclude that indirect changes occurred during the preliminary domestication of both annual and perennial species of Lesquerella used in our experiment. These changes were against those required if these species were to be developed as crops for semi-arid, mediterranean environments and should result in low seed-yield stability.