enhancing water productivity of direct seeded basmati rice ( OryzasativaL.) . In: Proc. Nat. Symp. on Agricultural Diversification for Sustainable livelihood and Environmental Security . Ludhiana, Punjab, India. pp. 180 – 181
Authors:H. El-Sharkawi, M. Irshad, A. M El-Serfy, T. Honna, and et al.
The use of poor quality water for agriculture is now receiving major attention especially in arid and semi-arid regions. This experiment was carried out to evaluate the effects of different irrigation water qualities on the grain yield and nutrient uptake of rice and on the heavy metal concentration in the grains. Six water treatments were applied at intervals of three days, involving either fresh water (FW), drainage water (DW), mixed water (MW), fresh water followed by drainage water (1FW + 1DW), two applications of fresh water followed by one of drainage water (2FW + 1DW) or one application of fresh water followed by two of drainage water (1FW + 2DW). The rice grain yield and the uptake of nitrogen (N), phosphorus (P) and potassium (K) were determined. The grains were also analysed for the concentration of nickel (Ni), cadmium (Cd) and lead (Pb). The results showed that the grain yield, the uptake of N, P and K in the plant biomass and the concentration of heavy metals in the grains were significantly affected by the water quality. The rice grain yield exhibited a close correlation with the water quality. The highest grain yield was obtained in the FW treatment and the lowest yield in the DW treatment. The uptake of N, P and K was detrimentally affected by poor quality water. However, the uptake trend for these elements was similar across all the irrigation treatments. The concentrations of heavy metal in the grains were significantly higher in plots irrigated with poor quality water. Among the treatments the cumulative concentrations of heavy metal were in the order of: DW ≯1FW + 2DW ≯ MW ≯ 1FW + 1DW ≯ 2FW + 1DW ≯ FW. This study showed that there is a potential risk of heavy metal contamination in rice crops treated with poor quality water. The lower grain yield after irrigation with poor quality water could be due to the disturbed mineral nutrition or to relatively higher salt toxicity.
Authors:N. Kumar, Nitin Kumar, A. Shukla, S. C. Shankhdhar, and D. Shankhdhar
Global warming is rising as a serious concern affecting agricultural production worldwide. Rice is a staple food crop and the threshold temperature for its pollination is 35 °C. A rise in temperature above this value can cause pollen sterility and may severely affect fertilization. Therefore, a study emphasizing the rise in temperature with respect to pollen viability was conducted with eleven rice genotypes during kharif seasons of 2010 and 2011 in indigenous field conditions. Increasing mean temperature by 12 °C at full flowering was found to severely affect the spikelet attributes of the crop. All genotypes showed spikelet sterility above 90% during both seasons. The study indicated that increased temperature may limit rice yield by affecting spikelet fertility and grain filling. The net reduction in grain yield was 30.4% and 27.6% in 2010 and 2011, respectively. A clear reduction in pollen size under high temperature was shown by scanning electron microscopy.
Authors:S.L. Krishnamurthy, S.K. Sharma, R.K. Gautam, and V. Kumar
Effects of salinity on correlation, path and stress indices, yield and its components were studied in a set of 34 promising rice genotypes collected from various national and international organizations. These genotypes were evaluated in a randomized complete block design with three replications during the wet seasons (kharif) of 2009 and 2010 in normal (ECiw ∼ 1.2 dS/m) and salinity stress (ECiw ∼ 10 dS/m) environments in micro plots at Central Soil Salinity Research Institute (CSSRI), Karnal, India. Grain yield per plant showed positive significant association with plant height, total tillers, productive tillers, panicle length, and biological yield per plant and harvest index under normal environment, whereas grain yield showed positive significant association with biological yield and harvest index under salinity stress. These results clearly indicate that selection of high yielding genotypes would be entirely different under normal and saline environments. The stress susceptibility index (SSI) values for grain yield ranged from 0.35 (HKR 127) to 1.55 (TR-2000-008), whereas the stress tolerance index (STI) values for grain yield ranged from 0.07 (PR 118) to 1.09 (HKR 120). The genotypes HKR 120, HKR 47 and CSR-RIL-197 exhibited higher values of stress tolerance index (STI) in salinity. Under salinity, negative and significant association was shown by SSI and grain yield in contrast to positive and significant association shown by STI and grain yield. These associations could be useful in identifying salt tolerant and sensitive high yielding genotypes. The stress susceptible and stress tolerance indices suggest that the genotypes developed for salinity tolerance could exhibit higher tolerance, adaptability and suitability. Harvest index and biological yield traits emerged as the ideal traits for improvement through selection and could be used to increase the rice productivity under saline stress environments.
To understand the molecular details of T-DNA integration, the left border (LB) sequences and flanking plant DNA of 16 independent T-DNA insertions in transgenic
rice were analyzed by an inverse PCR approach. DNA sequencing indicated that five of the 16 fragments (31%) were found to have simple or rearranged tandem repeats of right border sequences in a head to tail fashion. Mirror truncations of LB of the T-DNA, as well as mirror rearrangements, such as point mutations, small deletions and inversions were found in the region close to the LB breakpoints in some inserts. Host plant DNA flanking the T-DNA endpoints were also sequenced. The A+T contents in the plant DNA within 50 bp adjacent to the T-DNA endpoints were between 30–76% (average 52.5%), not different from the average genome value. Despite minor mutations and some rearrangements, it appears that T-DNA, harbouring a synthetic
coding sequence of 49% GC (as well as
), still carries such a foreign gene into ‘transcriptionally active regions’ of the rice genome, which are 55.8% GC on average as predicted from the rice genome sequence.
Authors:Raheem Shahzad, Muhammad Waqas, Abdul Latif Khan, Khadija Al-Hosni, Sang-Mo Kang, Chang-Woo Seo, and In-Jung Lee
Bacterial endophytes from the phyllosphere and rhizosphere have been used to produce bioactive metabolites and to promote plant growth. However, little is known about the endophytes residing in seeds. This study aimed to isolate and identify seed-borne bacterial endophytes from rice and elucidate their potential for phytohormone production and growth enhancement. The isolated endophytes included Micrococcus yunnanensis RWL-2, Micrococcus luteus RWL-3, Enterobacter soli RWL-4, Leclercia adecarboxylata RWL-5, Pantoea dispersa RWL-6, and Staphylococcus epidermidis RWL-7, which were identified using 16S rRNA sequencing and phylogenetic analysis. These strains were analyzed for indoleacetic acid (IAA) production by using GC-MS and IAA was found in the range of 11.50 ± 0.77 μg ml−1 to 38.80 ± 1.35 μg ml−1. We also assessed the strains for plant growth promoting potential because these isolates were able to produce IAA in pure culture. Most of the growth attributes of rice plants (shoot and root length, fresh and dry biomass, and chlorophyll content) were significantly increased by bacterial endophytes compared to the controls. These results show that IAA producing bacterial endophytes can improve hostplant growth traits and can be used as bio-fertilizers.