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The Triticum pathotype of Magnaporthe oryzae (syn. Pyricularia oryzae) causes wheat blast, which has recently spread to Asia. To assess the potential risk of wheat blast in rice–wheat growing regions, we investigated the pathogenicity of 14 isolates of P. oryzae on 32 wheat cultivars, among which Oryzae pathotype of P. oryzae (MoO) isolates were completely avirulent on the wheat cultivars at 22°C but caused various degrees of infection 25°C. These reactions at 25°C were isolate and cultivar dependent, like race-cultivar specificity, which was also recognized at the heading stage and caused typical blast symptoms on spikes. Microscopic analyses indicated that a compatible MoO isolate produced appressoria and infection hyphae on wheat as on rice. When we compared transcriptomes in wheat–MoO interactions, the bulk of pathogen-related genes were upregulated or downregulated in compatible and incompatible patterns, but changes in gene transcription were more significant in a compatible pattern. These results indicate that temperature could influence the infection ratio of wheat with MoO, and some MoO strains could be potential pathogens that increase the risk of wheat blast outbreaks in wheat–rice growing regions with global warming. In addition, certain wheat cultivars exhibited resistance and are assumed to carry resistance-promoting genes to the MoO strains.

In agricultural systems, it is vital to use limited yet optimal phosphorus (P) resources, because excessive P fertilizer application leads to the accumulation of P in soil, increasing the risk of environmental pollution and causing the waste and exhaustion of P resources. In a rice-wheat rotation system, omitting P fertilizer application in the rice-growing season is a good alternative; however, how this P fertilization reduction influences changes in P in the soil-root-aboveground system is unclear. In this study, after a seven-year rice-wheat rotation at the Yixing (YX) and Changshu (CS) sampling sites, China, compared with P fertilization in rice- and wheat-growing seasons (PR+W), reduced P fertilization (no P fertilizer application in either season, P0; P fertilization only in wheat-growing seasons, PW; and P fertilization only in rice-growing seasons, PR) did not result in substantial variation in crop biomass. The PW treatment did not reduce crop total P, root iron (Fe)-plaque P, and soil Olsen-P at three stages of rice growth (seedling, booting, and harvesting stages) at the YX and CS sites. In contrast, concentrations of soil Olsen-P, aboveground crop total P, and root Fe-plaque P decreased in the P0 treatment by 45.8%–81.0%, 24.6%–30.9%, and 45.6%–73.4%, respectively. In addition, a significant negative correlation was observed between the root Fe-plaque P and crop biomass at the two sites. Significant positive correlations were also observed between root Fe-plaque P and root total P, crop total P, and soil Olsen-P. In addition, the results of a redundancy analysis revealed that soil alkaline phosphatase (ALP) played a major role in the supply of P in soil, and was closely associated with root Fe-plaque P. The results of this study will enhance the understanding of the changes in P in the soil-root-aboveground system, particularly under P fertilizer reduction regimes.

In the rice-wheat rotation area, Cd contamination affects food safety of rice and wheat. However, there have been conflicting results and different conclusions on the difference in Cd accumulation capacity of rice and wheat, and the factors that led to the difference were not clear. A field survey study was conducted by collecting 60 soil and grain samples in pairs during rice and wheat harvest in 30 long-term rice-wheat rotation areas with clean and mild Cd contamination in Jiangsu Province, China. The soil physicochemical properties, total Cd, soil available Cd, and grain Cd were determined, and the factors affecting Cd accumulation in rice and wheat were analyzed. The soil pH during wheat season (22 sampling points) was slightly higher than that during rice season; thus, soil available Cd in wheat was generally lower (with an average three times lower) than that in rice soil. The mean Cd content in rice grain was only half of that in wheat grain, and the Cd concentration in rice and bioconcentration factor of rice at 26 sampling points (86.7% of total samples) were lower than those of wheat, indicating that Cd accumulation capacity of wheat was stronger than that of rice. Pearson correlation coefficient and multivariate linear regression models revealed that the main factors affecting the difference of Cd accumulation in rice and wheat were soil pH and available Cd content in soil. The Cd accumulation capacity of wheat was higher than that of rice, especially in neutral and alkaline soil, and the Cd contents in rice and wheat grain depended on the soil pH and available Cd content. The food security risk of wheat was more noteworthy than rice in rice-wheat rotation area.

Declining productivity of rice-wheat system in Indo–Gangetic Plains poses risk to conventional practices because of high production cost and low input use efficiency. Four crop establishment methods (CEM) and four weed management practices (WMP) were compared in a 2–year study to determine the productivity and profitability of rice-wheat system. Growth, yield traits and yields of rice was uninfluenced by CEM. Zero tillage rice (ZTR)–zero tillage wheat (ZTW) exhibited highest improvement in mean wheat yield, system productivity and profitability by 7.5%, 4.0% and 16.0%, respectively over conventional tillage rice (CTR)–conventional tillage wheat (CTW). CTR–ZTW recorded minimum total weed density and biomass in system. Post emergence application of bispyribac 25 g ha-1 + azimsulfuron 35 g ha-1 (bis + azim) in rice at 20 days after sowing (DAS)/days after transplanting (DAT); clodinofop 60 g ha-1 + carfentrazone 20 g ha-1 (clod + carf) in wheat at 30–35 DAS minimized total weed density and biomass, increased growth, productivity and profitability of the system. Results suggest that higher growth, productivity and profitability of rice–wheat system may be achieved by adoption of ZTR–ZTW with application of bis + azim in rice and clod + carf in wheat.

Wheat plays an important role in attaining food and nutritional security in Bangladesh after rice. The demand of wheat has been increasing every year at the rate of 13% due to rapid changes in dietary habits, socio-economic upliftment, enhancement of per capita income, etc. Bangladesh Wheat and Maize Research Institute (BWMRI) has already released 34 high yielding, disease-resistant, and abiotic stress-tolerant wheat varieties, and improved management practices to the farmers. Although all the released varieties have climatic yield potential as high as 6.0 t ha−1 with the attainable average yield is 4.0–4.5 t ha−1, the national average yield in farmers’ field is only 3.49 t ha−1; it is specified that there is a huge yield gap existing among potential, attainable and actual yields. One of the most important reasons for this yield gap of wheat is the terminal high temperature stress (HS) in late sowing wheat. Generally, farmers in Bangladesh are sowing wheat lately due to delay in sowing monsoon rice and subsequent late harvest of the rice; as a result, late sown wheat faces terminal HS at reproductive stage. The chapter highlighted the consequences of terminal HS on wheat and potential approaches to mitigate the stress in Bangladesh.

Reducing chemical fertilization is one of the best management practices in agro-ecosystems where soil phosphorus (P) has accumulated to excessive levels. However, few studies have focused on the response of soil microbes to decreases in P input in a rice-wheat rotation. To determine the feasibility of a P reduction regime and its impacts on soil microbes, we modified P fertilizer inputs in a four-year pot experiment. Our treatments contained P fertilization during both rice and wheat seasons (PR + W), P fertilization during wheat-growing season only (PW), P fertilization during the rice season only (PR), and no P fertilization during either rice or wheat season (Pzero) as the control. We used ten paddy soils with varied P levels, including P-rich, P-moderate, and P-low. After four years of rice-wheat cropping, the PW treatment maintained crop yields but reduced soil Olsen-P accumulation by 20.8–88.7% (p

Fue investigada la actividad antagónica in vitro de un total de 51 cepas pertenecientes a 16 géneros fúngicos detectados con mayor frecuencia en el filoplano del centeno, arroz y maíz.El antagonismo fue observado con el método de los cultivos duales en medios con agar, entre estos hongos y los fitopatógenos: Drechslera oryzae, Pyricularia oryzae y Helminthosporium maydis. Los más antagónicos son: Penicillium chrysogenum, P. thomii y Stachybotrys atra; ellos antagonizaron en particular con Botrytis cinerea, Fusarium moniliforme y Alternaria alternata. El antagonismo más exitoso contra los tres patógenos mencionados fue con P. chrysogenum y P. charlesii, quienes fueron notoriamente activos. Las cepas de Chaetomium globosum, Gibberella zeae, Fusarium moniliforme, Trichothecium roseum y B. cinerea presentan una actividad antagónica contra H. maydis; Cladosporium cladosporioides contra P. oryzae y D. oryzae; Aspergillus clavatus frente a D. oryzae. Los resultados son discutidos en relación al control biológico de estos patógenos de cereales

Rice and wheat are the main crops of the eastern part of Uttar Pradesh. Butachlor and 2,4-D are the two herbicides, which are very popular among rice growers. Studies on the estimation of herbicide residues present in the soil of rice and wheat grown in sequence were undertaken through bioassay technique. Results revealed that butachlor 1.5 kg/ha pre-emergence applied in rice did not leave its residue in the soil of rice after harvest. Isoproturon 1.0 kg + 2,4-D sodium salt 0.5 kg/ha at 30–35 days of sowing wheat also did not leave residue in the soil. In another long-term trial in rice-chickpea cropping system, butachlor 1.5 kg/ha pre-emergence and anilofos 0.5 kg/ha pre-emergence applied in rice did not leave their residue in the soil of rice.

With recent developments in phenotyping and genetics tools, biofortification programs around the world have significantly contributed to reducing malnourishment, particularly of iron (Fe) and zinc (Zn), in populations that depend upon on cereals as staple foods. As a polygenic trait, several quantitative trait loci (QTLs) for grain Zn or Fe levels have been mapped in the wild relatives of important crops, and these show a common genetic basis with some orthologous chromosomes in both rice and wheat, and with a few positively transgressed. Rice and wheat cultivars with target levels of grain Fe and Zn have been developed and released commercially. However, integration of agronomic biofortification with transgenic approaches and mapping for variation in density of Fe and Zn within endosperm for enhanced bioavailability and stability of traits in different environments are still in progress. Moreover, strategic advocacy for the awareness, demand, and acceptability of studies for scaling up the delivery of biofortified varieties is required to achieve additional health benefits globally.

In the Taihu Lake Region (TLR) of China, farmers’ injudicious and excessive use of phosphorus (P) fertilizer has led to a dramatic spike in P accumulation. In view of that, the water flooding practice can increase soil P release and enhance P availability in rice season, compared with the strong P fixation in wheat season; it seems possible to save P fertilizer in rice season with the aim of reducing P loads without any crop yield declines. To validate this possibility, a 4-year pot experiment encompassing eight rice/wheat seasons and using four paddy soils with varying Olsen-P contents (6.16 to 40.95 mg kg−1) was conducted to compare rice/wheat yield, inorganic and organic P accumulation under four different P regimes, P fertilization for both rice and wheat (PR + W; conventional practice), P fertilization only for wheat (PW), P fertilization only for rice (PR), and no P fertilization for both seasons (Pzero). Compared with conventional PR + W treatment, PR treatment significantly decreased wheat yields, especially in medium- and low-P soils, with an Olsen-P concentrate decline of 34.4–62.8 %. In contrast, PW treatment showed no significant difference in the rice/wheat yields over 4 years irrespective of high-, medium-, and low-P-concentrated soils, despite the soil Olsen-P concentration declining by 34.9–64.4 %. This highlights the feasibility of omitting P fertilizer application to flooded rice for at least 4 years in rice/wheat cropping paddy fields while maintaining crop yields and reducing environmental risk. In four paddy soils, available inorganic P was the dominant effective P source and increased with the concentration of Olsen-P. Without P fertilization over time, the concentration of soil inorganic P fractions declined and organic P remained relatively constant. According to the P supply capacity of different soils under the regime of omitting P fertilization for rice, how to utilize the bioavailability of P in different P supply capacity soils when P fertilization is omitted for rice crops will be required in future work.

To understand the effect of heat and drought on three major cereal crops, the physiological and biochemical (i.e., metabolic) factors affecting photosynthesis were examined in rice, wheat, and maize plants grown under long-term water deficit (WD), high temperature (HT) and the combination of both stresses (HT-WD). Diffusional limitations to photosynthesis prevailed under WD for the C3 species, rice and wheat. Conversely, biochemical limitations prevailed under WD for the C4 species, maize, under HT for all three species, and under HT-WD in rice and maize. These biochemical limitations to photosynthesis were associated with Rubisco activity that was highly impaired at HT and under HT-WD in the three species. Decreases in Rubisco activation were unrelated to the amount of Rubisco and Rubisco activase (Rca), but were probably caused by inhibition of Rca activity, as suggested by the mutual decrease and positive correlation between Rubisco activation state and the rate of electron transport. Decreased Rubisco activation at HT was associated with biochemical limitation of net CO2 assimilation rate (AN). Overall, the results highlight the importance of Rubisco as a target for improving the photosynthetic performance of these C3 (wheat and rice) and C4 (maize) cereal crops under increasingly variable and warmer climates.

Biomolecules are converted by the action of enzymes during the germination process and these are translocated to the growing seedlings serving as an enzyme source and for the synthesis of new biomolecules. The objective in the present study was to quantify the enzymatic activity of �≤ -galactosidase and alanineamino transferase in rice, wheat, ragi and bajra on different days of germination. Germination was carried out for a period of 8 days. The enzymes activity increased differentially to an exten ton the different days on germination in rice, wheat, ragi and bajra. This indicates the breakdown of molecules differs and the mechanism which is operating during the germination varies from species tospecies,depending on the requirement for the developing seedlings.

The impact of the combined effects of heat stress, increased vapor pressure deficit (VPD) and water deficit on the physiology of major crops needs to be better understood to help identifying the expected negative consequences of climate change and heat waves on global agricultural productivity. To address this issue, rice, wheat, and maize plants were grown under control temperature (CT, 25°C, VPD 1.8 kPa), and a high temperature (HT, 38°C, VPD 3.5 kPa), both under well-watered (WW) and water deficit (WD) conditions. Gas-exchange measurements showed that, in general, WD conditions affected the leaf conductance to CO2, while growth at HT had a more marked effect on the biochemistry of photosynthesis. When combined, HT and WD had an additive effect in limiting photosynthesis. The negative impacts of the imposed treatments on the processes governing leaf gas-exchange were species-dependent. Wheat presented a higher sensitivity while rice and maize showed a higher acclimation potential to increased temperature. Rubisco and PEPC kinetic constants determined in vitro at 25°C and 38°C were used to estimate Vcmax, Jmax, and Vpmax in the modeling of C3 and C4 photosynthesis. The results here obtained reiterate the need to use species-specific and temperature-specific values for Rubisco and PEPC kinetic constants for a precise parameterization of the photosynthetic response to changing environmental conditions in different crop species.

The production of cereals, including rice, wheat, and maize has increased in China over the past 20 years. However, variations in the production and cultivated area of cereals remains unclear. In this study, we collected and analyzed the cereal production and cultivated area in China from 1998 to 2016. An 85% increase in cereal production was recorded from 1998 to 2016, due to an increase in the maize production along with the increase in the cultivated area. Meanwhile, rice and wheat production have been stable since 2000. No change occurred in the rice cultivated area through 2016, and a 19% decrease in the wheat cultivated area was observed in 2016 relative to 1998. In addition, a significant positive relationship was observed among cereal production, maize production, and cultivated area (p &lt, 0.0001). Together, the increase in cereal production in China over the past two decades has resulted from the increase in maize cultivated area and the consequent increase in maize production.

On-farm conservation and utilization of crop landraces have been proposed as means of conserving plant germplasm, in contrast to ex situ germplasm conservation, but little is known about the effectiveness of this approach. This paper reports the findings from a survey conducted in 15 unique ethnic groups of the Yunnan Province on the conservation and utilization of paddy rice, wheat (including wheat, barley, oats, and rye) and maize landrace varieties through participatory rural appraisal (PRA) and questionnaires. The surveyed regions covered 306 villages (the village group) from 237 administrative villages in 124 towns (township) distributed in 36 counties of 11 prefectures (city) in Yunnan Province. The survey showed that 44.8%, 77.5%, and 37.3% of the visited villages had lost their paddy rice, wheat, and maize landraces, respectively. A total of 901 landraces were collected, including 371 rice, 119 wheat, and 411 maize varieties, respectively. There were 2.9 on-farm varieties on average per village, 3.3, 8.0 and 5.2 varieties on average per 100 households, 1 000 peasants and 100 Ha farmland areas, respectively. Among the 306 villages, two villages (Laomian and Qingkou) maintained the highest crop diversity with 18 varieties (including 10 rice and 8 maize varieties) and 14 paddy rice varieties. Also, on-farm varieties in different ethnic groups varied significantly from each other, ranging from 16 to 120 varieties per group. The diversity of paddy rice varieties was the highest, ranging from 1 to 72, and the diversity was mainly distributed in southern, southwest Yunnan of tropical, subtropical ethnic regions. The wheat varieties ranged from 0 to 47 and distributed in northern, northwest Yunnan of high altitude, temperature, and cold ethnic regions. The maize varieties ranged from 4 to 40. These patterns of variation in on-farm varieties are directly associated with traditional culture and custom for the ethnic minorities and reflect the lack of improved varieties for the local special environments. These findings confirm the role of on-farm conservation in plant genetic resources in China and provide baseline information for better on-farm conservation and utilization of plant germplasm in China.

The yield gap and the production constraints in the rice-wheat (R-W) system in eastern Uttar Pradesh were studied. The yield gap II (difference between the yield obtained at nearest demonstration plot and actual yield obtained on farmers' fields in a particular region) has been found 45 percent and 38 percent in rice and wheat crops, respectively, in the irrigated rice-wheat system. The technological and socio-economic constraints have accounted for 54 percent and 46 percent of the yield gap, respectively, in the system. Soil-related constraints rank first, followed by weed-related constraints. Among the individual constraints, zinc deficiency rank first followed by nitrogen deficiency and incidence of Phalaris minor. The study has concluded that for the sustainability of the R-W system, priority should be accorded to bridge the existing yield gap through addressing the production constraints. DOI: http://dx.doi.org/10.3329/bjar.v36i4.11749 Bangladesh J. Agril. Res. 36(4): 623-632, December 2011

The effect of earthworms on humus composition and humic acid (HA) characteristics was studied in a rice–wheat rotation agroecosystem. Experimental plots in the rotation had five treatments, i.e., incorporation or mulching of maize residues with or without added earthworms and a control. Compared with the control, the application of maize residues to soil either alone or in combinations with earthworms strongly affected the humus composition and HA characteristics. In the presence of earthworms, the carbon ratio of HA to fulvic acid (FA), and the alkyl C/O-alkyl C and hydrophobic C/hydrophilic C ratios of HA were slightly higher, while the aliphatic C/aromatic C ratio of HA was slightly lower following maize residue incorporation than the same treatment without earthworms. In contrast, these ratios generally remained almost constant following maize residue mulching. Thus, earthworm activity following maize residue incorporation was more favorable for the HA formation, and was associated with a decrease in aliphaticity of HA, and an increase in its degree of humification and hydrophobicity.

Seed germination of plants with various acid-resistance display different responses to acid rain. To understand the reason why such differences occur, the effects of simulated acid rain (pH 2.5–5.0) on the activities of peroxidase (POD) and catalase (CAT) during seed germination of rice (O. sativa), wheat (T. aestivum), and rape (B. chinensis var. oleifera) were investigated. Results indicated that the maximum change in activities of CAT and POD by acid rain treatment with different acidity and time in relation to the referent treatment without acid rain, was in the order: rice (28.8%, 31.7%) < wheat (34.7%, 48.3%) < rape (79.3%, 50.0%). The pH level for which the treatment with acid rain did not cause significant difference (p < 0.05) was in the order: rice (3.5).wheat (4.0).rape (5.0). Moreover, the change in activity of POD was higher than that of CAT, which showed that POD was more sensitive to acid rain stress than CAT. The difference in the ability of POD and CAT in removing free radicals was one reason why the germination indexes of these three species behaved differently.

Nine Tibetan weedrace, 9 Xingjiang rice wheat and 14 Yunnan hulled wheat accessions were evaluated for the variability of HMW-glutenins and gliadins. Higher variability was observed for both HMW-glutenins and gliadins in Tibetan weedrace and Xingjiang rice wheat, while lower variability was observed in Yunan hulled wheat. There were 4 HMW-glutenin and 9 gliadin patterns in 9 Tibetan weedrace accessions, 5 HMW-glutenin and 8 gliadin patterns in 9 Xingjiang rice wheat accessions, and 3 HMW-glutenin and 8 gliadin patterns in 14 Yunnan hulled wheat accessions. In Xinjiang rice wheat, one accession (i.e. Daomai 2) carried subunits 2.1 + 10.1 encoded by Glu-D1, which is very rare in common wheat.

A long-term rice-wheat experiment was conducted at Parwanipur, Nepal, to study the effects of organic and mineral sources of nutrients on yield and nutrient status of the soil. Twelve treatments comprising different combinations of inorganic N, P, and K; farmyard manure (FYM); and wheat chopped straw (WCS) were included. On average during a 20-year period, the control plot with an indigenous nutrient supply supported 2.06 Mg rice ha–1 and 0.69 Mg wheat ha–1. The application of 100 kg N ha–1 increased yields, but the addition of P, K, Zn, and S gave no response, indicating that the soil supply of these nutrients did not limit yield. The grain yield of rice and wheat was maintained over the years. Soil analyses of the past 6 years (1994–1999) showed that treatments receiving organic sources of nutrients increased total soil C and N from 18% to 62% and 15% to 48%, respectively, compared with the NPK treatment. There was a buildup of total P and Olsen P in plots receiving FYM. However, total and available soil K were similar in all the treatments. The apparent N and P balances for the rice-wheat system were positive in the NPK, FYM, and WCS treatments, whereas the K balance was negative in all the treatments except with the application of FYM to both rice and wheat. Rice and wheat in most years yielded

On-farm research to evaluate the productivity and nitrogen (N) nutrition of a rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping system was conducted with 21 farmers in the piedmont of Nepal and with 21 farmers in northwest Bangladesh. In Nepal, two levels of N-fertilizer (0–22–42 and 100–22–42 kg N–P–K ha−1) and farmers’ nutrient management practices were tested in the rice season, and three levels of N (0–22–42, 70–22–42, and 100–22–42) and farmers’ practices were evaluated in the wheat season. The treatments in Bangladesh included a researchers managed minus-N plot (0–22–42) and the farmers’ practices. Rice and wheat yields were higher in all treatments than the 0–22–42 control plots, with the exception of rice with the farmers’ practices at one location in Bangladesh. The researchers’ treatment of 100–22–42 in Nepal resulted in larger yields of both rice and wheat than the farmers’ practices, indicating that farmers’ rates of N-fertilizer (mean 49 kg N ha−1) were too low. Delaying wheat seeding reduced yields in the fertilized plots in both countries, especially as N-fertilizer dose increased. Soil N-supplying capacities (SNSC), measured as total N accumulation from the zero-N plots (0–22–42), and grain yields without N additions were greater for rice than for wheat in both Nepal and Bangladesh. Higher SNSC in rice was probably due to greater mineralization of soil organic N in the warm, moist conditions of the monsoon season than in the cooler, drier wheat season. However, SNSC was not correlated with total soil N, two soil N availability tests (hot KCl-extractable NH4+ or 7-day anaerobic incubation), exchangeable NH4+ or NO3−. Wheat in Nepal had greater N-recovery efficiency, agronomic efficiency of N, and physiological efficiency of N than rice. Nitrogen internal-use efficiency of rice for all treatments in both countries was within published ranges of maximum sufficiency and maximum dilution. In wheat, the relationship between grain yield and N accumulation was linear indicating that mobilization of plant N to the grain was less affected by biotic and abiotic stresses than in rice.

The relationship between rice cropping practices, biotic constraints, and rice yield levels in the eastern part of Uttar Pradesh, India was studied. The investigation was conducted at the centre of a geographic area representative of the rice-wheat system of South Asia, and covers a large diversity of production situations undergoing intensification. A survey procedure was used to collect data for 3 consecutive years (1993–1995) in 251 individual farmers' fields. Two analytical approaches were used, the emphasis shifting from yield determining variables, that are mostly qualitative in nature, to quantitative, and predominantly yield-reducing, variables. The first approach was intended to characterize relationships among variables using cluster and correspondence analyses, while the second approach was aimed at generating yield loss estimates using combinations of principal components and step-wise multiple regressions. Seven patterns of cropping practices were distinguished, reflecting a wide variation in production situations, especially in terms of use of fertilizers and manure, and degree of water control. Six types of disease profiles, four insect injury profiles, and four weed infestation patterns were identified. Correspondence analysis, based on patterns of cropping practices and injury profiles, yielded a path of increasing attainable yield associated with varying levels of intensification and combinations of injuries. The use of principal component analysis with multiple regression generated estimates of yield reductions due to rice diseases, insects and weeds. The analysis highlighted the effects of changes in patterns of cropping practices on injuries caused by weeds, brown spot, sheath blight and dead hearts. The significance of these findings with respect to current and future IPM needs is discussed.

Diversity analysis of biocontrol Bacillus isolated from rhizospheric soil of rice–wheat ( Oryza sativa – Triticum aestivum L.) at India

Protoplasts are used as source material for a range genetic manipulations. The use of molecular and somatic genetics in plant breeding should facilitate the selection and enhancement of the production of plants with desirable characters.The main tendency in the modern biotechnology is described in this review. It is shown the recent success in plant regeneration from rice and wheat protoplasts using fine, highly dispersed cell suspension cultures as a protoplast source.Different procedures related with gene transfer in rice and wheat using protoplast fusion and recombinant DNA technology are presented. Also, another methods for stable transformation such as pollen tube way, agroinfection, microprojectile bombardment, microinjection are discussed in the review. However, such techniques are still very much at the experimental stage and several major drowbacks must be overcome before they can be applied to agricultural practice but the efforts should be well worthwhile.

A survey was done recently in Jiaxing city of Zhejiang Province in the Yangtze River Delta to compare the differences of soil microbiological properties among paddy soils with different land use including continuous open-field vegetable cultivation (OFVC), plastic-greenhouse vegetable cultivation (PGVC) and traditional rice–wheat rotation (RWR). The soil types included are percolating, permeable and waterlogged paddy soils. The results indicate that the microbial flora was markedly changed as the land use changed for all the three soil types. In continuous vegetable cultivation soils, especially in PGVC soils, the bacteria amounts decreased dramatically, but the fungal and actinomyce amounts increased as compared with RWR soils. The dehydrogenase activities decreased significantly in vegetable soils, especially in PGVC soils as compared with RWR soils. The microbial biomass C and the total phospholipid contents (TPL) in vegetable cultivation soil greatly decreased as compared with RWR soils. Biolog analysis indicated that the kinds of carbon sources that could be metabolized by native microbes in PGVC soils greatly decreased as compared with OFVC soils and RWR soils, revealing that microbial diversity had decreased since land use change. The activities of some soil enzymes including urease, invertase and phosphase were all lower in OFVC soils than those in RWR soils, and those in PGVC soils were the lowest. The degradation of microbiological activities in continuous vegetable cultivation soils, especially in PGVC soils, as compared with RWR soils might have been caused by soil acidification and accumulation of salts due to overuse of both organic and inorganic fertilizers in vegetable cultivation.

Three bacterial isolates were obtained from the roots of rice, wheat and kallar grass. These isolates fix nitrogen in pure culture as confirmed by acetylene reduction assay in semi-solid nitrogen-free growth media. Production of growth hormones by these isolates was confirmed by colorimetric method. The isolates from wheat (strain Wb-3) and rice (strain N-4) were identified as Azospirillum brasilense and A. lipoferum, respectively, on the basis of their morphology, carbon utilization pattern and biochemical tests. The isolate K-1 from kallar grass, previously identified as Azospirillum brasilense, was confirmed to belong to a newly named genus Azoarcus (Reinhold-Hurek et al., 1993) by using 16S rRNA-targeted oligonucleotide probes and some morphological and physiological characteristics.

The study was conducted at three villages under Birganj upazilla of Dinajpur district to select suitable mungbean genotype to fit in the rice-wheat-fallow cropping system. Nine advanced mungbean genotypes and a check variety were tested in the farmers' fields through mother and baby trials managed by the farmers themselves. The mother trials were laid down in a radomized completely block design with three replications. Based on farmers' judgment regarding field performances and post-harvest evaluation on growth, field duration, seed yield, taste, cooking and milling quality, VC3960-88 appeared as the most preferred genotype. Farmers also preferred VC6153B-20P next to the above genotype. The baby trials conducted in thirty farmers' field reaffirmed that VC3960-88 was also the most preferred genotype. The performance of genotypes in baby trials and subsequent preference of the farmers signified the role of mother-baby trial approach towards selecting mungbean genotype by themselves. Key words: Variety, mungbean, selection, cropping system, PR & D approach. DOI: 10.3329/jard.v7i1.4419 J Agric Rural Dev 7(1&2), 33-40, June 2009

Consequent on the present shortage of rice and other cereals both in India and in other parts of Asia, it has become increasingly necessary to make up the deficit of starchy foods from other sources. The most promising sources are roots and tubers like tapioca and sweet potato which give two to three times higher yields of calories per acre than the commoner cereals. In fact, in Travancore and certain other parts of southern India, tapioca already forms a substantial part of the diet of the people. Tapioca and sweet potato, however, are deficient in proteins, and by themselves can serve mainly as sources of energy. In an earlier publication from this laboratory (Murthy, Swaminathan & Subrahmanyan, 1950) it was reported that in experimental animals: (I) poor diets, based mainly on tapioca or sweet-potato flour, did not support life; (2) addition of groundnut- cake flour at a level of 20 yo to these diets enhanced the nutritive value of the diets to an even higher level than that of rice diet; and (3) replacement of rice in a poor rice diet to the extent of 25 yo by a mixture of four parts of tapioca flour and one part of groundnut-cake flour produced a marked improvement in the nutritive value of a rice diet. Further systematic studies were therefore undertaken with a view to confirming the above findings, and to find out whether similar beneficial results could be obtained with other cereals. At the same time, it was considered to be of some practical importance to investigate the effect on the nutritive value of the rice diet of replacing varying percentages of rice by tapioca flour.