Effect of Seedling Age and Density on Growth and Yield of Rice in Saline Soil
ABSTRACT Two field experiments were carried out in saline soil receiving fertilizers NPK @ 130-75-75 kg ha-1, respectively, to see the effect of seedling age and number of seedling hill-1 on rice growth and yield. Rice seedlings of 25-, 35- and 55-day-old were transplanted in puddled field. Results revealed that seedlings of 25- to 35-day-old produced significantly higher number of tillers and productive tillers hill-1, paddy and straw yields compared with 55-day-old seedlings. In the second experiment, transplanting of two and three seedlings hill-1 of 35-day-old gave more promising results compared with one and four seedlings. Two seedlings hill-1 caused maximum increase in plant height, straw and paddy yield while more number of tillers and productive tillers were recorded with three seedlings hill-1.
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ABSTRACT: Salinity tolerance in rice varies with the state of growth, with the seedling and reproductive stages being the most sensitive. However, association between tolerances at the two stages is poor, suggesting that they are regulated by different processes and genes. Tolerance at the reproductive stage is the most crucial as it determines grain yield. An F2 mapping population was developed from two rice genotypes contrasting in tolerance: Cheriviruppu and Pusa Basmati 1 (PB1). Cheriviruppu is highly tolerant at the reproductive stage, while PB1 is highly sensitive at both seedling and reproductive stages. One hundred and thirty-one microsatellite markers polymorphic between the parents were used to construct a linkage map of 1458.5 cM (Kosambi), with a mean intermarker distance of 11.1 cM. Sixteen QTLs with LOD values ranging from 3.2 to 22.3 were identified on chromosomes 1, 7, 8 and 10, explaining 4–47 % of the phenotypic variation. The maximum number of QTL clusters for different component traits was colocalized on the long arm of chromosome 1 and chromosome 7. We identified several significant epistatic interactions, including three inter-QTL interactions, using MapManager. The results suggest that pollen fertility, Na+ concentration and Na/K ratio in the flag leaf are the most important mechanisms controlling salt tolerance at the reproductive stage in rice. The study reports the construction of a genetic map for reproductive-stage salt tolerance in rice and demonstrates its utility for molecular mapping of QTLs controlling salinity tolerance-related traits, which will be useful in marker-assisted selection in the future.Journal of Agronomy and Crop Science 07/2014; · 2.15 Impact Factor
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ABSTRACT: The system of rice intensification (SRI) aims to improve rice (Oryza sativa L.) yields through multiple management practices that have been presumed to interact synergistically. This study evaluated (i) the performance of SRI-component practices on salt-affected soils, and (ii) possible synergistic effects behind SRI's productive potential. Two replicated experiments were conducted in the Chokwé District, Mozambique in 2004 and 2005. The main trial was established at two sites differing in salinity levels and involved factorial arrangements of irrigation management (flooded, intermittent), compost application (12 Mg ha−1, none), plant spacing (30 cm × 30 cm, 20 cm × 20 cm) and variety (ITA312, IR52). The second trial involved three seedling ages (10-, 20- and 30-days old), and varieties. In each trial soil samples were collected prior to planting and soil chemical and physical properties analyzed. Intermittent irrigation reduced grain yields by 41–46% compared to conventional flooding. Compost application increased (12–13.5%), and wider spacing decreased grain yields (2.2–11%), as did higher transplant seedling age in the first year (9.3, 8.6 and 7.8 Mg ha−1 for 10-, 20- and 30-days old seedlings, respectively), but not in the second year. Rice compensated for decreased plant density by increasing yield per plant through more tillers and panicles. Interactions among practices were minimal, and in some cases antagonistic among SRI practices. In conclusion, several individual practices, including intermittent irrigation, compost application, and row spacing impacted grain yield, with SRI overall resulting in reduced rice yields. Synergistic effects of SRI practices were not observed for salt-affected soils.Field Crops Research. 01/2008;
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ABSTRACT: Studies were initiated for two consecutive years to find out the effect of time of transplanting and seedlings hill(-1) on the productivity of rice in Dera Ismail Khan district of North West Frontier Province (NWFP), Pakistan. The experiment was laid out in a randomized complete block design with split plot arrangements. Main plots consisted of four transplanting dates viz. 20th and 27th of June and 4th and 11th of July while sub-plots contained 1, 2, 3 or 4 seedlings hill(-1). Among transplanting dates, June 20th planted crop gave highest paddy yield and net return with 1 seedling hill(-1). It explains that the use of more seedlings hill(-1) not only adds to cost but is also a mere wastage of natural resources. Based on research findings, we conclude that the use of 1 seedling hill(-1) is most appropriate for timely sowing otherwise 4 seedlings hill(-1) should be used to compensate for the yield gap in late transplanted rice.Journal of Zhejiang University SCIENCE B 08/2006; 7(7):572-9. · 1.11 Impact Factor