Grain Yield Of Upland Rice Research Articles

Does Use of Unbordered Plots Affect Estimation of Upland Rice Yield?

ABSTRACTAdvance in crop genomics have led to a demand for more accurate and precise phenotyping of a large number of genotypes for discovering genes and mechanisms underpinning important agronomic traits. The use of unbordered plots for field phenotyping is one approach for reducing the resources needed, but competition effects between neighboring lines may confound varietal performance. Four field experiments were conducted in Benin to examine whether grain yields of 14 diverse upland rice (Oryza sativa spp.) varieties determined in unbordered one‐row or two‐row plots differ from those measured in self‐bordered four‐row plots and to examine if statistical models including covariates based on plant characteristics (height, panicle number, and days to heading) for correcting competition effect can improve the estimation of the yield in unbordered plots. Mean grain yield across all varieties ranged from 118 to 378 g m−2 in four experiments. There was no significant variety × row number interaction effect on grain yield, except for the highest yielding experiment. In that experiment, the variety × row number interaction was significant for one‐row versus four‐row plots, but not for two‐row versus four‐row plots. In one‐row plots in this high‐yielding experiment, the neighborhood covariate model based on panicle number improved residual mean square by 20%, but relative selection intensity by 3% only. Similarly, the covariate models based on height or panicle number in both one‐ and two‐row plots in the other experiments improved just 4%. We conclude that unbordered one‐ or two‐row plots can provide reasonable estimates of grain yield of upland rice without any bias due to competition effects, except for high‐yielding one‐row plots (>350 g m−2).

Gypsum and phosphorus in the development of upland rice under a no-tillage system

The use of gypsum in a no-tillage system may be a feasible alternative for cultivating upland rice because of its ability to move some nutrients to greater depth in the soil and thereby stimulate root growth. Additionally, phosphorus is one of the nutrients that most limits crop production in the Brazilian Cerrado. Thus, the objective of this work was to study the effect of combining gypsum (applied to the soil surface without tillage) and phosphorus at sowing on soil attributes, plant height, number of panicle m-1, seed mass, and grain yield in a no-tillage cultivation system. The experiment was conducted using a randomized complete block experimental design with four replicates in a factorial scheme of gypsum doses (0, 1000, 2000 and 3000 kg ha-1), phosphorus doses in the furrow (0, 50, 100 and 150 kg ha-1) and growing seasons (2011/2012 and 2012/2013). Gypsum applications provided incremental increases in soil calcium and increased potassium levels in the deeper soil layers, but it did not affect plant height, number of panicle m-1, or grain yield of upland rice cultivated under a no-tillage system. Increasing doses of phosphorus applied at sowing resulted in a significant increase in the plant height, number of panicles m-1 and grain yield. Key words: Oryza sativa L., fertilization, Cerrado, leaching.

Nitrogen, Phosphorus and Potassium Interactions in Upland Rice

Upland rice is an important crop in South America, including Brazil. Nutrient interactions are important in determining crop yields. A greenhouse experiment was conducted to evaluate interaction among nitrogen (N), phosphorus (P), and potassium (K) in upland rice production. The treatments applied to upland rice grown on an Oxisol were three levels of N (N0, N150 and N300 mg kg−1), three levels of P (P0, P100 and P200 mg kg−1) and three levels of K (K0, K100 and K200 mg kg−1). These treatments were tested in a 3 × 3 × 3 factorial arrangement. Grain yield, shoot dry weight, plant height, root dry weight, maximum root length, panicle number, 1000-grain weight, and grain harvest index were significantly influenced by N, P, and K treatments. The treatment that did not receive P fertilization did not produce panicle or grain. Hence, P was most yield-limiting nutrient compared to two other nutrients. At the N0P0K0 treatment, rice did not produce grains, indicating severe deficiency of these nutrients in Brazilian Oxisols. Maximum grain yield was obtained with the N300P200K200 treatment. Grain yield had significant positive association with plant height, shoot dry weight, root dry weight, maximum root length, 1000-grain weight, panicle number, and grain harvest index. Among these growth and yield components, shoot dry weight had the highest positive association with grain yield and root length minimum positive association with grain yield. Hence, adopting adequate soil and crop management practices can improve growth and yield components and increase grain yield of upland rice.

Influence of Lime and Gypsum on Growth and Yield of Upland Rice and Changes in Soil Chemical Properties

Upland rice is an important crop in the cropping systems of South America, including Brazil. Two greenhouse experiments were conducted to determine influence of lime and gypsum on yield and yield components of upland rice and changes in the chemical properties of an Oxisol. The lime rates used were 0, 0.71, 1.42, 2.14, 2.85, and 4.28 g kg−1 soil. The gypsum rates were 0, 0.28, 0.57, 1.14, 1.71, and 2.28 g kg−1. Lime as well as gypsum significantly increased plant height, straw and grain yield, and panicle density in a quadratic fashion. Adequate lime and gypsum rates for maximum grain yield were 1.11 g kg−1 and 1.13 g kg−1, respectively. Plant height, straw yield, and panicle density were positively related to grain yield. Lime as well as gypsum application significantly changed extractable calcium (Ca), magnesium (Mg), hydrogen (H)+aluminum (Al), base saturation, and effective cation exchange capacity. In addition, liming also significantly increased pH, extractable phosphorus (P) and potassium (K), calcium saturation, magnesium saturation, and potassium saturation. Optimum acidity indices for the grain yield of upland rice were pH 6.0, Ca 1.7 cmolc kg−1, base saturation 60%, and calcium saturation 47%. In addition, upland rice can tolerate 42% of acidity saturation.

Growth, Nutrient Uptake Efficiency and Yield of Upland Rice as Influenced by Two Compost Types in Tropical Rainforest-Derived Savannah Transition Zone

Cultivating traditional upland rice cultivars on nutrient depleted soil causes poor and low yield. Little attention is paid to performance of inter-specific NERICA cultivars grown on nutrient deficient soil augmented with different types of compost. Therefore, field trials were conducted during 2010 and 2011 planting seasons in Ibadan to evaluate growth, dry matter, nutrient uptake efficiency and grain yield of upland rice grown on nutrient deficient soil augmented with different types of compost. There were nine treatments comprising of three upland rice cultivars: NERICA I, NERICA II and Ofada, two compost types applied at the rate of 8 t·ha-1: poultry dropping + maize stover (PDMC) and cattle dung + maize stover (CDMC) and control. The treatments were laid out in randomized complete block design and replicated three times. CDMC enhanced growth, nutrient use efficiency, dry matter and grain yield of upland rice cultivars. Performance of Ofada was better than NERICA cultivars. N (24.55 g), P (12.45 g) and K (35.41 g) uptake concentration and grain yield (5.45 t/ha) were highest in Ofada plots augmented with CDMC. Residual effect of compost on growth, yield and nutrient uptake efficiency of upland rice on nutrient deficient soil was marginal.

Upland rice under no-tillage preceded by crops for soil cover and nitrogen fertilization

The grain yield of upland rice under no-tillage has been unsatisfactory and one reason could be the nitrate/ammonium balance in the soil. Cover crops and nitrogen fertilization can be used to change the nitrate/ammonium relation in the soil and improve conditions for the development of upland rice in the no-tillage (NT) system. The aim was to study the effect of cover crops and nitrogen sources on grain yield of upland rice under no tillage. The study was carried out on the Fazenda Experimental Lageado, in Botucatu, State of São Paulo, Brazil, in an Oxisol area under no-tillage for six years. The experiment was arranged in a randomized block split-plot design with four replications. The plots consisted of six cover crop species (Brachiaria brizantha, B. decumbens, B. humidicola, B. ruziziensis, Pennisetum americanum, and Crotalaria spectabilis) and the split-plots of seven forms of N fertilizer management. Millet is the best cover crop to precede upland rice under NT. The best form of N application, as nitrate, is in split rates or total rate at topdressing or an ammonium source with or without a nitrification inhibitor, in split doses. When the cover crops C. spectabilis, B. brizantha, B. decumbens, B. humidicola, and B. ruziziensis preceded rice, they induced the highest grain yield when rice was fertilized with N as ammonium sulfate source + nitrification inhibitor in split rates or total dose at topdressing.

Grain yield and arsenic uptake of upland rice inoculated with arbuscular mycorrhizal fungi in As-spiked soils

A pot trial was conducted to investigate the effects of three arbuscular mycorrhizal (AM) fungi species, including Glomus geosporum BGC HUN02C, G. versiforme BGC GD01B, and G. mosseae BGC GD01A, on grain yield and arsenic (As) uptake of upland rice (Zhonghan 221) in As-spiked soils. Moderate levels of AM colonization (24.1-63.1 %) were recorded in the roots of upland rice, and up to 70 mg kg(-1) As in soils did not seem to inhibit mycorrhizal colonization. Positive mycorrhizal growth effects in grain, husk, straw, and root of the upland rice, especially under high level (70 mg kg(-1)) of As in soils, were apparent. Although the effects varied among species of AM fungi, inoculation of AM fungi apparently enhanced grain yield of upland rice without increasing grain As concentrations in As-spiked soils, indicating that AM fungi could alleviate adverse effects on the upland rice caused by As in soils. The present results also show that mycorrhizal inoculation significantly (p < 0.05) decreased As concentrations in husk, straw, and root in soils added with 70 mg kg(-1) As. The present results suggest that AM fungi are able to mitigate the adverse effects with enhancing rice production when growing in As-contaminated soils.

Gas exchange rates, plant height, yield components, and productivity of upland rice as affected by plant regulators

The objective of this work was to evaluate gas exchange rates, plant height, yield components, and productivity of upland rice, as affected by type and application time of plant growth regulators. A randomized block design, in a 4x2 factorial arrangement, with four replicates was used. Treatments consisted of three growth regulators (mepiquat chloride, trinexapac-ethyl, and paclobutrazol), besides a control treatment applied at two different phenological stages: early tillering or panicle primordial differentiation. The experiment was performed under sprinkler-irrigated field conditions. Net CO2 assimilation, stomatal conductance, plant transpiration, and water-use efficiency were measured four times in Primavera upland rice cultivar, between booting and milky grain phenophases. Gas exchange rates were neither influenced by growth regulators nor by application time. There was, however, interaction between these factors on the other variables. Application of trinexapac-ethyl at both tillering and differentiation stages reduced plant height and negatively affected yield components and rice productivity. However, paclobutrazol and mepiquat chloride applied at tillering, reduced plant height without affecting rice yield. Mepiquat chloride acted as a growth stimulator when applied at the differentiation stage, and significantly increased plant height, panicle number, and grain yield of upland rice.

Effect of cultural methods on Striga (Striga hermonthica (Del.)) Benth management and yield of cereals in the Savanna Zone of Nigeria: a review

Data were obtained from the research done in the Guinea Savanna (Zaria 11°11′N; 070 38′E) and Sudan Savanna (Maiduguri −11°51′N; 13°15′E) regions of Nigeria, respectively on different cultural methods of Striga control and management. In the Guinea Savanna, trials on the effects of nitrogen on the response of resistant and susceptible upland rice varieties to Striga hermonthica infestation and the effect of resistant and susceptible varieties of maize and crop rotation on Striga infestation was carried out, while the effect of inter-cropping trap crop (Bambaranut) with resistant sorghum varieties on S. hermonthica was studied in the Sudan Savanna Zone of Nigeria. In the Guinea Savanna, it was observed that a combination of upland rice variety, Faro 40 and an application of 90 kg N/ha in the wet season and WAB 56-50 upland rice variety and 120 kg N/ha in the dry season, respectively reduced Striga infestation and produced maximum grain yield. Also, the growing of resistant variety of maize (Across 97ITZ comp. I-W) after 1 or 2 years' rotation with cowpea or soybean was observed not only to be effective in Striga control, but resulted in higher grain yield of maize. In the Sudan Savanna, the use of resistant varieties of sorghum, 1CSV1002 and 1CSV1007 intercropped with bambaranut significantly reduced Striga infestation, but the grain yield of the resistant varieties was low. From these studies, Faro 40 with 90 kg N/ha application rate and WAB56–50 with 120 kg N/ha were suitable for the management of Striga and for higher grain yield of upland rice in both wet and dry seasons, respectively, while Across 97ITZ comp. I-W, resistant maize variety and 1 or 2 years rotation with cowpea or soybean were also the best for the management of S. hermonthica and for higher maize yield in the Guinea Savanna zone. Further research needs to be carried out in the Sudan Savanna to select a high yielding resistant variety of sorghum which when intercropped with bambaranut will not only control Striga infestation but will also give high grain yield.

Involvement of peduncle elongation, anther dehiscence and spikelet sterility in upland rice response to reproductive-stage drought stress

Reproductive stage drought stress results in dramatic reduction of spikelet fertility and grain yield of upland rice ( Oryza sativa L.). The hypothesis investigated here is that spikelet sterility under pre-anthesis drought is triggered by deficient plant water status that inhibits peduncle elongation, panicle exsertion and anther dehiscence. A set of 45 rice genotypes was grown in an upland field under well-watered and drought-stressed conditions. Irrigation was applied using a drip irrigation system, and the drought stress treatment was initiated differentially for each genotype at 10–15 days before heading. Drought stress substantially reduced grain yield, and the average yield in the drought treatment was only 20% of that of the control. Peduncle elongation rate (PER) was significantly inhibited by drought, simultaneously with the decrease of plant water status parameters. Yield was highly associated with spikelet fertility ( r = 0.74***), PER ( r = 0.47***), leaf water potential (LWP) ( r = −0.4**), and peduncle water potential (PWP) ( r = −0.38**). The sensitivity of anther dehiscence to drought stress, as determined by the anatomic structure of anther walls, did not differ among genotypes. Path analysis revealed that spikelet fertility and PER had a major positive effect on yield, while peduncle length and LWP had negative effects. PWP had a small direct effect, but had a high negative indirect effect on yield through spikelet fertility reduction. PER had a high and positive indirect effect on yield under drought through spikelet fertility. It is concluded that PER is key parameter that affects rice yield through the regulation of spikelet fertility by plant water status under drought.

Componentes da produção e produtividade de cultivares de arroz e feijão em função de calcário e gesso aplicados na superfície do solo

A utilização do gesso agrícola e de cultivares mais tolerantes à acidez do solo podem ser alternativa para viabilizar o cultivo em sistema plantio direto sem a incorporação prévia do calcário. Este trabalho foi realizado com o objetivo de avaliar o efeito da aplicação superficial de calcário e gesso agrícola nos componentes da produção e na produtividade de grãos de cultivares de arroz e feijão. O experimento foi instalado em Latossolo Vermelho distroférrico, anteriormente manejado no sistema convencional de preparo do solo, em Botucatu (SP). O delineamento foi em blocos casualizados com parcelas sub-subdivididas e quatro repetições. Nas parcelas, os tratamentos foram os seguintes: quatro doses de calcário dolomítico (0, 1.100, 2.700 e 4.300 kg ha-1); nas subparcelas, aplicação ou não de 2.100 kg ha-1 de gesso agrícola; e nas sub-subparcelas, foram cultivadas duas cultivares de arroz de terras altas (Caiapó e IAC 202), no ano agrícola 2002/2003, e duas de feijão (Pérola e Carioca), em 2003/2004. O número de panículas por m², o número de espiguetas por panícula, a massa de mil grãos e a produtividade de grãos das cultivares de arroz aumentaram pela aplicação de calcário. A aplicação de gesso aumentou o número de panículas por m² e a produtividade de grãos da cultivar Caiapó, mas reduziu o número de panículas e não afetou a produtividade da cultivar IAC 202. A calagem, na ausência de gesso, aumentou o número de vagens por planta e a produtividade de grãos das cultivares de feijão. A aplicação de gesso reduziu o número de vagens por planta da cultivar Carioca de feijão, mas não alterou outros componentes da produção e a produtividade de grãos. A dose de calcário para elevar a saturação por bases a 70% foi a mais adequada para ambas as culturas. O uso de cultivares mais tolerantes à acidez do solo proporciona maior produtividade no início do sistema plantio direto, quando ainda não houve efetiva correção do solo pela aplicação de corretivos em superfície.

Optimizing tillage schedule for maintaining activity of the arbuscular mycorrhizal fungal population in a rainfed upland rice (Oryza sativa L.) agro-ecosystem

Rainfed uplands in India are predominantly mono-cropped with rice (Oryza sativa L.) in the wet season (June/July to September/October) and grown under aerobic soil conditions. The remaining fallow period (winter followed by summer) of about 8-9months leads to natural crash in the population of native arbuscular mycorrhizal fungi (AMF) in the soil. Attempts have been made to minimize this population crash by reducing soil disturbance-induced deleterious effects on native AMF activity of improperly scheduled off-season tillage, an agronomic recommendation for weed and disease (soil-borne) management, practiced by the upland farmers. On-farm (farmers' field) evaluation of effects of all suitable off-season tillage schedule combinations on rice during wet seasons of 2004, 2005, and 2006 revealed that a maximum of two off-season tillage schedules with a minimum gap of 13weeks between them minimized the population crash of native AMF with a concomitant increase in phosphorus (P) uptake and grain yield of upland rice (variety "Vandana").

Restos vegetais e adubação nitrogenada na micorrização e produtividade do arroz de terras altas em sistema plantio direto

The objective of this research was to verify the influence of plant residues and the nitrogen fertilization in covering on the mycorrhization (colonization and number of spores of the arbuscular mycorrhizal fungi), and grain yield of upland rice grown under a no tillage system. The experiment was conducted at the Experimental Farm Station of Unesp/Ilha Solteira Campus, at Selviria (Mato Grosso do Sul State). In the main plots, the leguminous were tested: sun hemp ( Crotalaria juncea L. ), pigeon pea ( Cajanus cajan L. ) and velvet bean ( Stizolobium aterrimum Piper & Tracy) and the grass: corn ( Zea mays L.), millet ( Pennisetum americanum L.) and grain sorghum ( Sorghum bicolor L.), plus no planted area during the winter, as plant cover. In the subplots, after the rice sowing, the nitrogen fertilization in covering (zero and 75 kg ha-1 of N at the urea form) was used. The rice grain yield was influenced by the plant residues, but not for the N doses or the interaction. The sorghum grain showed negative influence on the rice productivity. The nitrogen fertilization influenced the number of spores, but not the mycorrhizal colonization or the grain yield, at the time of the crop. Correlation between the studied variable was not found.

Effects of Nitrogen Nutrition on Grain Yield of Upland Rice and Paddy Rice under Different Cultivation Methods

Upland rice and dry-cultivated paddy rice have been attracted more and more attention because of limited water re- sources in China. Researches on interaction between water and nitrogen supplies for crop resistance to drought stress has become the hot topic regarding regulation on nutritional physiology. However, there is little information available on effect of nitrogen (N) nutrition on grain yield and its components of upland rice and paddy rice under different cultivation methods. The objective of this study was to evaluate the difference between upland rice and paddy rice and interaction between cultivation methods and N levels. One upland rice cultivar Zhonghan 3 (japonica) and one paddy rice cultivar Yangjing 9538 (japonica) were grown under moist cultivation (MC, control) or bare dry-cultivation (DC) with three N levels, low amount of N (LN, 100 kg ha-1), normal amount of N (NN, 200 kg ha-1), and high amount of N (HN, 300 kg ha-1). The results showed that, compared with NN, the grain yield under HN was lower for both upland and paddy rice under DC and for paddy rice under MC, whereas higher for upland rice under MC. With the increase in N levels, upland rice and paddy rice showed higher productive tillers, more or fewer spikelets per panicle, lower percentage of ripened grains under two cultivation methods. However, the percentage of ripened grains was reduced more for paddy rice than for upland rice. There was no significant difference in 1 000-grain weight for upland rice among three N levels, whereas grain weight was reduced with the increase in N levels. Compared with MC, DC showed no significant difference in grain weight for upland rice, whereas a significant decrease for paddy rice. DC significantly increased the percentage of ripened grains for both upland and paddy rice, and that were more for upland rice than for paddy rice. Compared with paddy rice, upland rice showed less number of adventitious roots, lower nitrogen absorption ability and lower productive tillering ability, fewer pani- cles, fewer spikelets per panicle and lower grain yield. However, upland rice exhibited quicker increase in adventitious roots and slower declining in leaf nitrogen content from jointing to heading, and a faster declining speed in chlorophyll content (SPAD value) after flowering. Also, upland rice had less negative response to water stress and more positive response to N. The results suggest that the response to cultivation methods and N levels varies largely between upland rice and paddy rice. The approaches to in- crease the grain yield of both paddy and upland rice were discussed.

Green manuring and nitrogen fertilization effects on soil chemical properties, agronomic traits and grain yield of upland rice

A field experiment was conducted at the University of Agriculture, Abeokuta (UNAAB), Nigeria to screen three green manure crops in the 1997 cropping season for biomass production. The most promising legume was selected, grown and incorporated insitu along with varying levels of inorganic nitrogen fertilizer. The effects of these treatments on agronomic trait and yield of upland rice and soil chemical properties were then investigated at UNAAB and Olowo-Papa village (OP). In the first experiment three green manure crops, namely, Mucuna utilis, Canavalia ensiformis and Lablab purpureus were screened for biomass production in a Randomized Complete Block Design with three replicates. The biomass of M. utilis (25.5 t/ha) was significantly higher than those of C. ensiformis (20.4 t/ha) and L. Purpureus (2.1 t/ha). The second experiment was laid out in a split- plot design at the two sites. Mucuna, which produced the highest biomass in the first experiment, was chosen as the green manure crop. The main plot was green manure (no green manure and green manure) and N-fertilizer constituted the subplot treatment (0, 30, 60 and 90 kg N/ha). The results showed that rice plants grown on green manure plot had higher panicles/m2, number of grains/panicle and grain yield than in the control plot. The contribution of green manure incorporation to grain yield was estimated to be 56%. The plot treated with 90 kg N/ha had the highest rice yield at OP. It was found that the response of rice to N fertilizer application depended on green manuring. Mucuna grown with the late rains as pre-rice green manure has the potential of increasing the grain yield of the subsequent rice crop. Keywords: Canavalia ensiformis; inorganic fertilization; Lablab purpureus; Mucuna utiliMoor Journal of Agricultural Research Vol. 7 (1&2) 2006 pp. 1-8

Produtividade de grãos e exportação de nutrientes de cultivares de arroz irrigadas por aspersão em conseqüência da época de semeadura

No sistema irrigado por aspersão, o uso de cultivares e épocas adequadas de semeadura podem possibilitar a obtenção de altos níveis de produtividade do arroz de terras altas. No entanto, são escassas as informações sobre a exportação de nutrientes pelos grãos dessa cultura nesse sistema de produção. Este trabalho objetivou avaliar o efeito da época de semeadura na produtividade e exportação de nutrientes pelos grãos de cultivares de arroz de terras altas (IAC 201, IAC 202, Carajás, CNA 7800 e CNA 7801), irrigados por aspersão. Os experimentos foram desenvolvidos nos anos agrícolas de 1995/1996 e 1996/1997, em Latossolo Vermelho distrófico, em Selvíria (MS). As semeaduras foram realizadas no início da segunda quinzena de setembro, outubro, novembro, dezembro, janeiro e fevereiro, de cada ano. Foi utilizado o delineamento de blocos ao acaso, em esquema de parcela subdividida, com quatro repetições. A época de semeadura influenciou a produtividade de grãos e exportação de nutrientes pelos grãos. A semeadura realizada em novembro proporcionou maior exportação de nutrientes por promover produtividades mais elevadas. Em épocas de semeadura antecipada (setembro), com a cultivar Carajás, a produtividade e a exportação de nutrientes foram superiores às demais; já nas semeaduras de outubro a dezembro, a cultivar CNA 7801 se destacou. No sistema irrigado por aspersão, é possível semeadura em fevereiro com produtividade acima 3.900 kg ha-1 utilizando as cultivares IAC 201 e Carajás.

Improvement of rice ( Oryza sativa L.) growth in upland conditions with deep tillage and mulch

The productivity of upland rice in Japan as well as in the world is low and unstable owing to scarce and unpredictable rainfall. The objective of this study was to examine whether agronomic methods could enhance grain yield of upland rice. Four field experiments were conducted from 2001 to 2003 in Nishitokyo, Japan, under upland conditions with different water supplies, in order to quantify the effects of deep tillage combined with deep placement of manure (50-cm depth), straw mulch (6 t ha −1), or their combinations on the growth and grain yield of rice. Mulch kept surface soil moisture higher than without mulch even at reproductive stage, and it increased yield to the greatest extent under the most favourable conditions with much rainfall before heading (i.e., 2003). Deep tillage with deep placement of manure induced deep root proliferation and higher nitrogen uptake, increasing biomass production, and panicle number, and consequently grain yield was enhanced under the two lowest yielding environments with less rainfall before heading. Rice plants with deep tillage with deep manure application without mulch tended to have lower leaf water potential and higher diffusion resistance during drought, and negative effects on grain filling and harvest index in some experiments compared with the control. When deep tillage with deep placement of manure was combined with mulching in two experiments in 2002 and 2003, grain yield always enhanced compared with the control ( P < 0.10, 6.0 t ha −1 versus 5.4 t ha −1 on average), suggesting their synergetic mechanisms for yield increase and stabilization. The results showed that deep tillage or mulching can improve grain yield of rice under drought-prone rainfed upland conditions in a temperate climate on an Andosol, and their combination had more consistent and greater positive effects.

Nutritional Diagnostic in Upland Rice Production in Some Municipalities of State of Mato Grosso, Brazil

Nutrient deficiency is one of the most important yield limiting factors in crop production in cerrado soils in Brazil. A survey was conducted with the objective to evaluate soil fertility and nutritional status of upland rice plants in 43 sites, covering 33 rural properties, in three Municipalities of the Chapada dos Parecis Region, State of Mato Grosso, Brazil. Grain yield of upland rice was also determined where soil and plant samples were taken for nutritional evaluation. Grain yield of upland rice varied from 975 to 7853 kg ha−1 with an average value of 3595 kg ha−1. Soil analysis showed average value of pH 5.5, organic matter (O.M.) 21.5 g dm−3, phosphorus (P) 4.1 mg dm−3, potassium (K) 31.6 mg dm−3, calcium (Ca) 17.7 mmol dm−3, magnesium (Mg) 8.4 mmol dm−3, and aluminum (Al) 1.8 mmol dm−3. Average micronutrients levels in the soil were 0.51 mg dm−3 of copper (Cu), 2.4 mg dm−3 of zinc (Zn), 61.6 mg dm−3 of iron (Fe), and 4.79 mg dm−3 of manganese (Mn). Similarly, average base saturation was 28%, Al saturation was 8%, Ca saturation was 18%, Mg saturation was 9%, K saturation was 0.82%, Ca/K ratio was 24, Ca/Mg ratio was 2.23 and Mg/K ratio was 12. Plant analysis showed average values of N 30.3 g kg−1, P 1.68 g kg−1, K 19 g kg−1, Ca 3.87 g kg−1, Mg 2.66 g kg−1, Zn 22 mg kg−1, Cu 8 mg kg−1, Mn 120 mg kg−1, and Fe 106 mg kg−1. Based on soil fertility analysis there were low levels of P, K, base saturation, Ca saturation, Mg saturation, K saturation and deficiencies of Cu, Zn, and Mn in some samples. Plant analysis showed deficiency of P, followed by deficiency of K and N. Among micronutrientes, plant analysis showed deficiencies of Zn, Cu, and Mn in some samples.

Produtividade do arroz irrigado por aspersão em função do espaçamento e da densidade de semeadura

Com o objetivo de estudar o efeito de três espaçamentos entre fileiras (30, 40 e 50 cm) e três densidades de semeadura (100, 150 e 200 sementes viáveis/m²) sobre o desenvolvimento da planta, os componentes da produção e a produtividade do arroz irrigado por aspersão até a tensão de reposição de água de -0,070 MPa, foi instalado um experimento em condições de campo, em um Latossolo Vermelho-Escuro, epieutrófico, textura argilosa, em Selvíria, MS. A cultivar avaliada foi a IAC 201. Esta cultivar apresenta suscetibilidade ao acamamento, no sistema de irrigação por aspersão, até uma tensão de reposição de água, no solo, de -0,070 Mpa. O número de colmos e de panículas é incrementado com a redução do espaçamento. A densidade de 100 sementes/m² é a mais indicada para a cultivar IAC 201 irrigada por aspersão, por proporcionar menor gasto de sementes. O espaçamento de 30 cm entre fileiras de plantas proporciona maior produtividade de grãos da cultivar IAC 201 no sistema de irrigação por aspersão.

Plant phosphorus and rice yield in an Ultisol of the humid forest zone in West Africa

Little attention has been devoted to calibrating plant tissue tests for phosphorus (P) in the field for upland rice in West Africa, although information is needed for improving crop production through efficient P nutrition. A field experiment was conducted under rainfed conditions in the 1994 season to establish the relationships between plant P content and grain yield of upland rice grown on an Ultisol, having a range in extractable P, in the humid forest zone of Ivory Coast. The critical limit of P content in the whole rice plant tops at the tillering stage, at 90% relative grain yield, was found to be 2 g kg‐1 P for the four upland rice cultivars tested. Total P uptake in the biomass was significantly correlated with rice grain (r=0.81, n=20) and straw (r=0.79) yields of the cultivars.