Phalaris minor Retz. has evolved multiple herbicide resistance in wheat growing areas in northwestern India. An understanding of the effect of growth stage on herbicide tolerance of wheat and control of P. minor will help in selecting the most appropriate herbicide for different situations. The weed control and crop safety of four commonly used wheat herbicides (sulfosulfuron, pinoxaden, fenoxaprop plus metribuzin and mesosulfuron plus iodosulfuron), each applied at four different wheat growth stages was investigated in field studies for two years. P. minor plants were at 1, 2-3, 3-4 and 7-8 leaf stages when the herbicides were applied at Zadok 12-Z12, Z13, Z21 and Z23 stages of wheat, respectively. Sulfosulfuron application at Z12 and Z13 wheat stages (before first irrigation), provided >80% control of P. minor and produced wheat grain yield (4.5-4.7 t/ha) similar to the weed-free check (4.9 t/ha) in both years. Pinoxaden, fenoxaprop plus metribuzin and mesosulfuron plus iodosulfuron application at Z12 and Z13 wheat stages recorded significantly lower wheat grain yield (3.62-3.95 t/ha) due to poor weed control, crop toxicity or both. All the four herbicides were equally effective on P. minor when applied at Z21 wheat stage. At Z23 wheat stage, pinoxaden gave >90% control of P. minor and the highest wheat grain yield (4.82 t/ha). The results are expected to allow changes in the current recommendation of the timing of postemergence herbicides for the management of P. minor in wheat.Additional key words: crop toxicity; crop stages; littleseed canarygrass; selectivity; Triticum aestivum.Correspondence should be addressed to Rubia Rasool: rubiarasool@yahoo.com; rasiarasool@gmail.com Abbreviations used: ALS (acetolactate synthase); DAS (days after sowing); DAT (days after treatment); Z (Zadoks).

Rice is the most important crop at the global level, as it used as a staple food in most of the countries of the world. Transplanting aged seedlings of paddy has a detrimental effect on the crop performance, which needs to be overcome for sustaining the productivity. Leaf colour chart based nitrogen application is an efficient and economical tool for enhancing the rice productivity and nitrogen use efficiency. With this in mind, a field experiment was conducted during kharif 2011, at the Research Farm of SKUAST-K, Shalimar, Srinagar (Kashmir) to optimize the seedling age of rice (Oryza sativa L.) under late transplanting conditions and to assess the suitability of using leaf colour chart as a nitrogen management tool to improve the performance of rice. The experiment was established in Randomized Block Design, with three replicates, 3 seedling ages and 6 nitrogen application treatments. The analyses of data revealed that 35 days old seedling recorded significantly higher total dry matter accumulation and dry matter partitioning to panicle (8.2 t ha-1) and leaf (2.4 t ha-1); grain yield (7.4 t ha-1); N, P and K uptake (11.6, 3.1 and 11.3 kg ha-1, respectively) (p<0.05). Among nitrogen application treatments significantly higher dry matter accumulation; yield (8.6 t ha-1) and N, P and K uptake (14.1, 3.6 and 12.7 kgha-1, respectively) was found in ½ N as basal and remaining at LCC <4 @20 kg ha-1 (p<0.05). Age of seedling and time of nitrogen application did not affect N, P, K and protein content of grain and straw significantly (p>0.05). It is concluded that the yield of rice can be improved by transplanting 35-days old seedling under late transplanted conditions in temperate regions and by following LCC guided nitrogen management.

The terminal residues of flufenacet were quantified in soil and wheat grains. Flufenacet was applied at 250 and 300 g/ha on 21 and 35 days after the sowing of wheat at the Research Farm of Punjab Agricultural University, Ludhiana. Matrix solid phase dispersion (MSPD) method was used for the extraction of flufenacet from soil and grain samples. The herbicide residues were quantified using High Performance Liquid Chromatography (HPLC) equipped with UV-Vis detector and were confirmed with gas chromatographic tandem mass spectrometry (GC-MS/MS). The average recoveries of flufenacet extracted from the matrix ranged from 80.9 to 93.0% and 88.0 to 96.2% when quantified using HPLC and GC-MS/MS, respectively with relative standard deviation less than 10%. Both HPLC and GC-MS/MS offer high reproducibility, however GC-MS/MS was more sensitive having limit of detection (LOD) and limit of quantification (LOQ) as 0.001 and 0.003 μg/g, respectively. Terminal residues of flufenacet in the soil and wheat grain samples were below the detectable limit. Thus, the use of flufenacet in wheat under subtropical humid conditions could be considered safe.

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