Yield Components Of Rice Research Articles

BIOCHAR AS SOIL CONDITIONER IN THE SUCCESSION OF UPLAND RICE AND COWPEA FERTILIZED WITH NITROGEN

ABSTRACT The effects of biochar and nitrogen application on yields of upland rice and cowpea and on soil fertility were determined in a greenhouse in Macaíba, RN, Brazil. The trial consisted of the succession of two crops in a completely randomized design and a factorial scheme, with four replicates. Initially, four doses of biochar and four doses of nitrogen were tested for cultivation of rice. Subsequently, four doses of biochar and two doses of nitrogen were tested in half of the pots maintained for planting cowpea. Soil was sampled after rice harvest for half of the pots and at end of the trial for the remaining pots. We evaluated the following parameters: mass of hundred grains of rice, dry shoot mass, panicle number, number of filled spikelets and of empty spikelets, and grain production. Determinations for cowpea were: pod number per pot, grain number per pod, and grain production per pot. Measured soil parameters were: pH, contents of organic carbon, P, K, Ca, Mg, Na, cation exchange capacity, and exchangeable sodium percentage. Biochar addition did not influence yield components of upland rice and cowpea, but resulted in increased soil N retention, which influenced rice dry shoot mass, spikelets sterility, panicle number, and grain mass. Biochar also promoted increased soil pH, potassium content, and exchangeable sodium percentage and decreased calcium and magnesium concentrations.

Influence of tiller heterogeneity on yield components of rice grown under different nitrogen regimes

Increase in rice yield under excessive nitrogen (N) supply is negligible, hence it is necessaryto analyze the limiting factors via yield components. The present study was carried out during2014 and 2015 growing seasons in order to quantify the yield componenents of different typesof tiller at various N levels. Tillers were divided into three different types (superior, mediumand inferior) based on their productivity. The results indicated that the quantitative proportionsand yield contributions were decreased in superior tillers, increased in the inferior tillers, whileremained stable in the medium tillers with increasing supply of N fertilizer. The increased rateof spikelets per panicle in the superior tillers was higher under all N application levels; however,a high quantitative proportion and the lower number of spikelets per panicle of the inferiortillers might have resulted in the reduced population of spikelets per panicle. The rates of grainfilling percentage and grain weight in medium and inferior tillers were decreased withincreasing N applications, which led to a decrease in population grain filling and grain weight.The present study suggested that the enhancement of grain filling and weight of the inferiortillers would be an effective approach to further improve the per acre yields of rice. Theacquisition of more accurate yield component data, in the perspective of tiller, might be helpfulfor researches regarding the development of augmented rice breeding architectures.

Effect of Planting Date, Spacing and Seeding Methods on Disease Development and Yield Components of Rice (Oryza sativa L.) in Southeastern Nigeria

Effect of Planting Date, Spacing and Seeding Methods on Disease Development and Yield Components of Rice (Oryza sativa L.) in Southeastern Nigeria

Field-based high throughput phenotyping rapidly identifies genomic regions controlling yield components in rice

To ensure food security in the face of population growth, decreasing water and land for agriculture, and increasing climate variability, crop yields must increase faster than the current rates. Increased yields will require implementing novel approaches in genetic discovery and breeding. Here we demonstrate the potential of field-based high throughput phenotyping (HTP) on a large recombinant population of rice to identify genetic variation underlying important traits. We find that detecting quantitative trait loci (QTL) with HTP phenotyping is as accurate and effective as traditional labor-intensive measures of flowering time, height, biomass, grain yield, and harvest index. Genetic mapping in this population, derived from a cross of an modern cultivar (IR64) with a landrace (Aswina), identified four alleles with negative effect on grain yield that are fixed in IR64, demonstrating the potential for HTP of large populations as a strategy for the second green revolution.

Effects of elevated CO 2 on rice grain yield and yield components: Is non-flooded plastic film mulching better than traditional flooding?

The atmospheric carbon dioxide (CO2) concentration has been increasing rapidly since the Industrial Revolution. The responses to elevated CO2 of rice (Oryza sativa L.) growth and yield have been widely reported, but the majority of these studies investigated rice grown under traditional flooding at two contrasting CO2 levels. The effects of a range of CO2 concentrations (CO2 gradient) on the yield and its components of rice grown under non-flooded vs. flooded conditions remain unclear. Using a CO2 Gradient Tunnel (CGT), we investigated the effects of elevated CO2 (450, 500, 550 and 600 μmol mol−1) on rice yield and yield components under two cultivation practices, viz. traditional flooding (TF) and non-flooded plastic film mulching (PM). Elevated CO2 increased rice yield by 25% under the TF treatment at 450–500 μmol mol−1, but had no effect or decreased the rice yield under the PM treatment. The number of panicles per square meter was decreased by 4–26% under progressive elevation of CO2 concentration, regardless of cultivation practice. Elevated CO2 increased the spikelet number per panicle and filled spikelet percentage under the TF treatment, but had no effect on these parameters under the PM treatment. Specifically, elevated CO2 decreased the number of degenerated spikelets on secondary rachis branches of rice grown under the TF treatment by 75%, but increased that of filled spikelets by 43%. This was the major reason for the CO2-induced increase in rice yield under the TF treatment. The 1000-grain weight and Harvest Index (HI) under the two cultivation practices was increased only when CO2 concentration was elevated to 550–600 μmol mol−1. The CO2 × cultivation interaction was detected for grain yield. When CO2 concentration was increased to 600 μmol mol−1, the rice yield of the PM treatment was 2% higher than the TF treatment. This study demonstrated that improved management practices are needed to maximize the benefits of non-flooded plastic film mulching cultivation in a CO2-rich world. Our results provide major implications for water management of rice production systems and global food security under future higher CO2, and potentially drier, environments.

Fine Mapping and Candidate Gene Analysis of the Tiller Suppression Gene ts1 in Rice.

Tiller number is one of the key factors that influences rice plant type and yield components. In this study, an EMS-induced rice tiller suppression mutant ts1 was characterized. Morphological and histological observations revealed that, in the ts1 plants, the tiller buds were abnormally formed and therefore cannot outgrow into tillers. With an F2 population derived from a cross between ts1 and an indica cultivar Wushansimiao, a major gene, tiller suppression 1 (ts1) was fine-mapped to a 108.5 kb genomic region between markers ID8378 and SSR6884 on the short arm of rice chromosome 2. Candidate gene analysis identified nineteen putative genes. Among them, ORF4 (LOC_Os02g01610) is a PPR gene which harbored a point mutation c.+733/C→T in ts1 mutant plants. A co-dominant SNP marker cd-733C/T was subsequently developed and the SNP assay demonstrated that the point mutation co-segregated with tiller suppression phenotype. Quantitative RT-PCR analysis showed that the expression level of ORF4 in ts1 plants was significantly lower than that in their wild plants, and the expression of rice tillering regulators MOC1 and HTD1 was also significantly decreased in ts1 plants. Our data indicated that ORF4 was a strong candidate gene for ts1 and ts1 might play a role in regulating rice tillering through MOC1 and HTD1 associated pathway. The results above provide a basis for further functional characterization of ts1 and will shed light on molecular mechanism of rice tillering. The informative SNP marker cd-733C/T will facilitate marker-assisted selection of ts1 in rice plant type breeding.

Participatory Evaluation and Determination of N and P Fertilizer Application Rate on Yield and Yield Components of Upland Rice (NERICA-4) at Bambasi District, Benishangul-Gumuz Regional State

Declining soil fertility is one of the major problems causing yield reduction of rice in Benishangul Gumuz Regional state. Therefore, field experiments were carried out at Bambasi District Assosa Zone, to evaluate and determine the effects of N and P fertilizer rate application on growth, yield and yield components of upland rice. The fertilizer treatments considered in the study was consist of four levels of N (0, 46, 92 and 138 kg N ha-1) and four levels of P (0, 23, 46, and 69 kg P2O5 ha-1). The experiment was laid out in a randomized complete block design (RCBD) with three replications at Sonka FTC and on three farmers fields consisting of a total of 16 treatments (mother trial). The results of the study revealed that most of yield and yield components of rice were significantly (P<0.05) affected by the main effect of N on mother and baby trails. Except grain per panicle, straw and grain yield; other parameters are not affected by the main effect of P fertilizer rate application. The highest grain yield (3244 kg ha-1) was recorded from 92 kg N ha-1 combined with 46 kg P2O5 ha-1 and the lowest grain yield (1415.6 kg ha-1) was recorded from the control treatment. Partial budget analysis also indicated that the highest net return (28548 Birr ha-1) was obtained from the application of 92 kg N ha-1 combined with 46 kg P2O5 ha-1 fertilizer rate. Thus, from the result of this study, it can be concluded that the application of 92 kg N ha-1 combined with 46 kg P2O5 ha-1 was found to be superior both agronomically and economically for rice NERICA-4 variety under main cropping season in the study area.

Effects of Paddy Soil Chemical Changes and Yield Components of Rice in Accordance with the Age and Usage of Organic Fertilizer and Chemical Fertilizers

Effects of Paddy Soil Chemical Changes and Yield Components of Rice in Accordance with the Age and Usage of Organic Fertilizer and Chemical Fertilizers

Effect of planting method and weeding regime on the performance of transplant Aman rice

An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh during July to December 2014 to evaluate the effect of planting method and weeding regime on the performance of transplant Aman rice. Two planting methods viz. line transplanting and haphazard transplanting and six weed control treatments viz. no weeding, one hand weeding at 21 DAT, two hand weeding at 21 and 42 DAT, pre-emergence herbicide Rifit 500 EC at 7 DAT, pre-emergence herbicide Rifit 500 EC at 7 DAT + one hand weeding at 42 DAT and weed free were used as experimental treatments with three replications in a randomized complete block design (RCBD). Planting methods, weeding treatment and their interaction significantly influenced most of the crop characters and yield components of transplant Aman rice. The highest effective tillers hill-1 (9.30),grain panicle-1 (185.4), grain yield (3.89 t ha-1), straw yield (5.57 t ha-1), biological yield (9.54t ha-1) and harvest index (41.08) were obtained from line transplanting. Complete weed free treatment produced the highest total tillers hill-1 (12.37), effective tillers hill -1 (9.89), grain yield (4.11 tha-1) and biological yield (9.94 t ha-1).The highest total tillers hill-1(13.07), effective tillers hill -1(10.70), grain yield (4.50t ha-1) and biological yield (10.79 t ha-1) were obtained from line transplanting under weed free treatment. Results revealed that line transplanting with pre-emergence herbicide Rifit 500 EC at 7 DAT + one hand weeding at 42 DAT might be used to control weeds effectively and to get higher yield of transplant Aman rice.Progressive Agriculture 27 (3): 249-255, 2016

Exploitation of heterosis loci for yield and yield components in rice using chromosome segment substitution lines.

We constructed 128 chromosome segment substitution lines (CSSLs), derived from a cross between indica rice (Oryza sativa L.) 9311 and japonica rice Nipponbare, to investigate the genetic mechanism of heterosis. Three photo-thermo-sensitive-genic male sterile lines (Guangzhan63-4s, 036s, and Lian99s) were selected to cross with each CSSL to produce testcross populations (TCs). Field experiments were carried out in 2009, 2011, and 2015 to evaluate yield and yield-related traits in the CSSLs and TCs. Four traits (plant height, spikelet per panicle, thousand-grain weight, and grain yield per plant) were significantly related between CSSLs and TCs. In the TCs, plant height, panicle length, seed setting rate, thousand-grain weight, and grain yield per plant showed partial dominance, indicating that dominance largely contributes to heterosis of these five traits. While overdominance may be more important for heterosis of panicles per plant and spikelet per panicle. Based on the bin-maps of CSSLs and TCs, we detected 62 quantitative trait loci (QTLs) and 97 heterotic loci (HLs) using multiple linear regression analyses. Some of these loci were clustered together. The identification of QTLs and HLs for yield and yield-related traits provide useful information for hybrid rice breeding, and help to uncover the genetic basis of rice heterosis.

Silicon improves rice grain yield and photosynthesis specifically when supplied during the reproductive growth stage

Silicon (Si) has been recognized as a beneficial element to improve rice (Oryza sativa L.) grain yield. Despite some evidence suggesting that this positive effect is observed when Si is supplied along the reproductive growth stage (from panicle initiation to heading), it remains unclear whether its supplementation during distinct growth phases can differentially impact physiological aspects of rice and its yield and the underlying mechanisms. Here, we investigated the effects of additions/removals of Si at different growth stages and their impacts on rice yield components, photosynthetic performance, and expression of genes (Lsi1, Lsi2 and Lsi6) involved in Si distribution within rice shoots. Positive effects of Si on rice production and photosynthesis were manifested when it was specifically supplied during the reproductive growth stage, as demonstrated by: (1) a high crop yield associated with higher grain number and higher 1000-grain weight, whereas the leaf area and whole-plant biomass remained unchanged; (2) an increased sink strength which, in turn, exerted a feed-forward effect on photosynthesis that was coupled with increases in both stomatal conductance and biochemical capacity to fix CO2; (3) higher Si amounts in the developing panicles (and grain husks) in good agreement with a remarkable up-regulation of Lsi6 (and to a lesser extent Lsi1). We suggest that proper levels of Si in these reproductive structures seem to play an as yet unidentified role culminating with higher grain number and size.

Variability and path co-efficient for yield and yield components in rice

Twenty five rice varieties were evaluated for their variability with regard to yield and yield components. Estimates of heritability and genetic advance as per cent mean were also obtained for the above traits. In addition, studies on character associations and path co-efficients were also undertaken. The results revealed high variability, heritability and genetic advance as per cent mean for productive tillers per plant, number of tillers per plant, number of grains per panicle and number of filled grains per panicle, while days to maturity was recorded with high heritability coupled with low genetic advance as per cent of mean. Further, yield was observed to be positively associated with number of tillers per plant, productive tillers per plant, number of grains per panicle and number of filled grains per panicle. Among these, number of tillers per plant, productive tillers per plant and number of filled grains per panicle were noticed to exert high direct effects on grain yield per plant. High indirect effects of most of the traits were noticed mostly through productive tillers per plant indicating importance of the trait as selection criteria in crop yield improvement programmes.Bangladesh J. Agril. Res. 41(2): 259-271, June 2016

Detection of additive and additive×environment interaction effects of QTLs for yield‐component traits of rice using single‐segment substitution lines (SSSLs)

AbstractAdditive effects (A) and additive‐by‐environment interactions (A×E) for five rice yield components were analysed using 20 SSSLs under mixed linear model methodology. Thirty‐one QTLs were detected. Different yield components have different QTL‐by‐environment (Q×E) interaction patterns. No A×E interaction effects were detected for the four QTLs for panicle number (PN). Four QTLs detected for spikelets per panicle (SPP) had A×E interactions. Five of seven QTLs detected for grains per panicle (GPP), two of 10 QTLs detected for 1000‐grains weight (GWT) and three of six QTLs detected for seed set ratio (SSR) showed significant A×E interaction. Most of these QTLs were distributed in clusters across the genome. The complexity of linkage and pleiotropy of these QTLs plus environmental effect may result in the diversity of the yield phenotype in the SSSLs. Only S19 exhibited a significant increase in yield with a predicted gain by 281.58 kg ha−1. The results may be useful to design a better breeding strategy that takes advantage of QTL‐by‐environment interaction effects in each of the SSSLs.

Effect of Foliar Boron Application on Rice (Oryza Sativa L.) Growth and Final Crop Harvest

Boron (B) is an essential micro nutrient and its deficiency caused a reduction in final crop harvest and quality of the yield. A field experiment was conducted to evaluate the effect of foliar application of B on yield and yield components of rice in calcareous soils under agro-climatic conditions of Lahore, Pakistan. The experiment was laid out in randomized complete block design (RCBD) with six B foliar application rates (0, 5, 10, 15, 20 and 25 mg L-1). The experiment was replicated three times. The results illustrated a significant effect of B foliar application on number of grains panicle-1, number of filled grains and final grain yield. The highest grain yield (352 g m-2) was recorded in 20 mg L-1 foliar application, whereas an increase in B application to 25 mg L-1 reduces the final grain yield significantly (313 g m-2). Detrimental effects of the highest B application on yield components were also observed. The decline in the quantity and quality rice yield resulted by increasing B application might be due to the toxic effect of higher concentration of B application.

Properties of a clay soil from 1.5 to 3.5 years after biochar application and the impact on rice yield

We assessed the impact of a single application of wood biochar on soil chemical and physical properties and aerobic rice grain yield on an irrigated kaolinitic clay Ferralsol in a tropical Savannah. We used linear mixed models to analyse the response of soil and plant variables to application rates of biochar (0, 8, 16 and 32tha−1) and mineral N fertilization (0, 30, 60 and 90kgNha−1), and their interaction. The response was analysed within three aerobic rice-growing seasons (S), equivalent to 1.5, 2.5 and 3.5years after biochar application (S1.5, S2.5 and S3.5). The fraction of oxidisable C in soil increased with biochar application rate, irrespective of N fertilization, at S2.5 and S3.5, whereas the rice stress-free available water (soil water retention between −6 and −100kPa) decreased with biochar application rate at S1.5 and S2.5. Rice grain yield and yield components varied with the seasons according to the changes in soil properties and weather conditions. A single application rate up to 32tha−1 of the wood biochar type used in this study had no impact on aerobic rice yield increase on a kaolinitic clay Ferralsol under the climatic conditions of the Brazilian Savannah prone to dry spells. Most likely, the beneficial effects of wood biochar on soil chemical properties on rice production were offset by a decrease in soil water retention capacity and N uptake by the crop.

Effect of plant establishment method and weeding on the yield and yield components of Boro rice

An experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, Mymensingh, Bangladesh during December 2013 to May 2014 to observe the effect of plant establishment method and weeding on the yield and yieldcomponents of boro rice cv. BRRI dhan29. The treatments included two plant establishment methods viz. direct seeding and transplantingusing the seedling of direct seeded plots; four weedings viz. no weeding, one weeding at 15 days after transplanting (DAT), two weedings at 15 and 30 DAT, three weedings at 15, 30 and 45 DAT.The experiment was laid out in a randomized complete block design with four replications. Yield contributing characters and yield of boro rice were influenced by plant establishment method and weeding. The highest plant height (79.24 cm), grains panicle-1 (121.90), grain yield (2.86 t ha-1), straw yield (3.56 t ha-1), biological yield (6.42 t ha-1) and harvest index (44.81%) were recorded by transplanting method. The highest number of total tillers hill-1 (17.48 ), effective tillers hill-1 (13.39), grain yield (3.38 t ha-1), straw yield (4.22 t ha-1), biological yield (7.61 t ha-1) and harvest index (47.01%) were obtained with three weeding at 15, 30 and 45 DAT. The lowest grain yield (1.69 t ha-1) and straw yield (2.42 t ha-1) were recorded from no weeding. The highest grain yield (3.65 t ha-1) was recorded from transplanting method with three weeding, which was statistically similar to transplanting method with two weeding. Again direct seeding method with three weeding resulted in similar yield with that of transplanting method with two weeding. The lowest grain yield (1.46 t ha-1) was recorded from direct seeding method with no weeding. From the present experiment it may be concluded that transplanting method with two weeding or direct seeding method with three weeding may be recommended for cultivation of modern bororice.Progressive Agriculture 27 (1): 27-31, 2016

Short and long-term effects of different irrigation and tillage systems on soil properties and rice productivity under Mediterranean conditions

Abstract In Mediterranean environments, flood irrigation of rice (Oryza sativa L.) crops is in danger of disappearance due to its unsustainable nature. The aim of the present study was to determine the short- and long-term effects of aerobic rice production, combined with conventional and no-tillage practices, on soils' physical, physicochemical, and biological properties, as well as on the rice yield components and productivity in the semi-arid Mediterranean conditions of SW Spain. A field experiment was conducted for three consecutive years (2011, 2012, and 2013), with four treatments: anaerobic with conventional tillage and flooding (CTF), aerobic with conventional tillage and sprinkler irrigation (CTS), aerobic with no-tillage and sprinkler irrigation (NTS), and long-term aerobic with no-tillage and sprinkler irrigation (NTS7). Significant soil properties improvements were achieved after the long-term implementation of no-tillage and sprinkler irrigation (NTS7). The short-term no-tillage and sprinkler irrigated treatment (NTS) gave lower yields than CTF in 2011 and 2012, but reached similar yields in the third year (NTS 8229 kg ha−1; CTF 8926 kg ha−1), with average savings of 75% of the total amount of water applied in CTF. The NTS7 data showed that high yields (reaching 9805 kg ha−1 in 2012) and water savings are sustainable in the long term. The highest water productivity was with NTS7 in 2011 (0.66 g L−1) and 2012 (1.46 g L−1), and with NTS in 2013 (1.05 g L−1). Thus, mid- and long-term implementation of sprinkler irrigation combined with no-tillage may be considered as a potentially productive and sustainable rice cropping system under Mediterranean conditions.

Seletividade de herbicidas sobre arroz irrigado em resposta à época de semeadura e redução da luminosidade em fases do desenvolvimento

RESUMO Diferentes fatores ambientais podem afetar a seletividade de herbicidas às culturas. O objetivo deste experimento foi avaliar os efeitos da época de semeadura e da redução artificial da luminosidade, em diferentes fases do desenvolvimento das plantas, sobre a seletividade de herbicidas e os componentes de produtividade do arroz irrigado. O experimento foi conduzido a campo, na safra 2012/2013, com o cultivar IRGA 424. Os fatores estudados foram: época de semeadura (18/outubro e 09/novembro); herbicidas (testemunha capinada, bispyribac-sodium e penoxsulam) e fases do desenvolvimento da cultura com luminosidade reduzida de 70% [testemunha, plântula (S0-V4), períodos vegetativo, reprodutivo e todo o ciclo]. Foi utilizado o delineamento inteiramente casualizado, em esquema fatorial, com quatro repetições, sendo que os fatores época de semeadura e redução de luminosidade foram dispostos em faixas, visando a viabilizar o experimento. Avaliaram-se: fitotoxicidade visual, colmos e panículas por área, espiguetas por panícula, esterilidade de espiguetas, peso de 1000 sementes e produtividade. Os dados foram submetidos à análise de variância pelo teste F (p≤0,05) e teste de médias de DMS de Fischer (p≤0,05). A época de semeadura influencia na seletividade de bispyribac-sodium, sendo que, quando realizada a semeadura perto do início do período recomendado, em 18/outubro, reduz-se a produtividade do cultivar estudado. A redução artificial de luz em diferentes fases do desenvolvimento não afeta a seletividade dos herbicidas bispyribac-sodium e penoxsulam sobre o arroz irrigado.

Analysis of Growth Characteristics and Yield Components According to Rice Varieties Between on Irrigated and Partially Irrigated Rice Paddy Field

국내 가뭄 조건에서의 벼 품종별 재배안정성을 평가하기 위한 인위적인 가뭄 처리 조건(수리불안전답 조건)에서 생육 특성과 쌀수량 조사하고 쌀수량 감소 요인을 분석한 결과는 다음과 같다. 1. 수리불안전답 조건에 의한 경수 및 이삭수 감소율은 품종에 따라 각각 10.7%에서 33.1%와 10.5%에서 30.1%였으며, 공시품종 중 '새일미', '일미'가 경수 및 이삭수 변화가 적었으며, '오대'와 '운광', '추청' 품종에서 경수와 이삭수 감소가 크게 나타났다. 2. 수리불안전답 조건에서의 쌀수량은 품종에 따라 수리안전답 조건보다 9.9%에서 33.3% 감소하였으며, 쌀수량 감소가 적은 품종은 '새일미'와 '주남', '일미'였으며, 감소율이 큰 것으로 조사된 품종은 '오대'와 '칠보', '호품' 등 이였다. 3. 수리불안전답 조건에 의한 생육초기 경수 발달 부진과 이의 영향에 의한 이삭수 감소가 쌀수량 감소에 가장 큰 영향을 준 것으로 분석되었다. 4. 본 연구에서 수리불안전답 조건에서의 쌀수량 감소를 분석한 결과, 국내 기상조건에서 발생할 수 있는 가뭄은 생육후기보다 생육초기의 경수 발달에 크게 영향을 주는 것으로 확인되었다. 따라서 농업용수 공급이 원활하지 않는 수리불안전답의 경우 가뭄에 대비하기 위하여 '새일미'와 '일미', '일품' 품종 같은 가뭄에 대한 재배안정성이 우수한 품종을 재배하는 것이 적당하다고 판단된다. Drought caused by global climate change is one of serious problems for rice cultivation. However, it was little reported the impact of drought on rice cultivation in Korea. In here, to assess impact of drought on rice varieties in Korean climate condition, growth characteristics and yield components of rice were compared on irrigated and partially irrigated rice paddy field. First, we have chosen 11 rice varieties including 'Saeilmi' and 'Shindongjin' which are widely cultivated in Korea. For partially irrigated rice paddy treatment, we have withheld irrigation from 25 days after transplanting and water supply was totally dependent on rainfall for rice cultivation. When we examined early plant height and tiller number of these varieties on partially irrigated rice paddy were reduced 1.6% to 18.4% and 10.4% to 33.1%, respectively, and these reduction rate were highly correlated with yield loss in our experimental conditions. Among rice yield components, panicle number was decreased 10.5% to 30.1% according to rice varieties and reduced panicle number was highly correlated with yield loss. Grain number per panicle, grain filling rate and 1,000 seeds weight did not have correlation with yield loss of rice varieties. These result means that growth stage, especially the tillering stage, is seriously affected by drought on rice cultivation in Korea. And we suggest that 'Saeilmi', 'Ilmi' and 'Ilpum' are good for rice cultivation on drought prone rice field in Korea.

Soil Texture and Cultivar Effects on Rice (Oryza sativa, L.) Grain Yield, Yield Components and Water Productivity in Three Water Regimes.

The objective of this study was to determine the effects of water regime/soil condition (continuous flooding, saturated, and aerobic), cultivar (‘Cocodrie’ and ‘Rondo’), and soil texture (clay and sandy loam) on rice grain yield, yield components and water productivity using a greenhouse trial. Rice grain yield was significantly affected by soil texture and the interaction between water regime and cultivar. Significantly higher yield was obtained in continuous flooding than in aerobic and saturated soil conditions but the latter treatments were comparable to each other. For Rondo, its grain yield has decreased with soil water regimes in the order of continuous flooding, saturated and aerobic treatments. The rice grain yield in clay soil was 46% higher than in sandy loam soil averaged across cultivar and water regime. Compared to aerobic condition, saturated and continuous flooding treatments had greater panicle numbers. In addition, panicle number in clay soil was 25% higher than in sandy loam soil. The spikelet number of Cocodrie was 29% greater than that of Rondo, indicating that rice cultivar had greater effect on spikelet number than soil type and water management. Water productivity was significantly affected by the interaction of water regime and cultivar. Compared to sandy loam soil, clay soil was 25% higher in water productivity. Our results indicated that cultivar selection and soil texture are important factors in deciding what water management option to practice.