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Subject: Agronomy × Author: Bansal, Tanu × Start date: 2020 × Thesis Type: M.Sc ×
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    Weed competitive abilities of rice genotypes in direct seeded rice (Oryza sativa L.)
    (Punjab Agricultural University, Ludhiana, 2021) Bansal, Tanu; Dhillon, Buta Singh
    Investigation entitled “Weed competitive abilities of rice genotypes in direct seeded rice (Oryza sativa L.)” was undertaken at Research Farm, Rice Section, Department of Plant Breeding and Genetics, Punjab Agricultural University, Ludhiana, India during Kharif 2020. The soil of experimental fields was sandy loam in texture, low in available nitrogen, high in available phosphorous and medium in available potassium and organic carbon. Experiment-I was laid out in split plot design keeping combinations of four crop-weed competition periods [weedy throughout (WT), weed free up to 15 days (WF15), weed free up to 30 days (WF30) and weed free throughout (WF-Th)] in main plot and eight genotypes (RYT 4004, RYT 4005, RYT 4079, RYT 4080, RYT 4081, PR 120, PR 126 and SAVA 134) in sub plots. Purple rice was used as surrogate weed in this experiment. Experiment-II was laid out in completely randomized design with two genotypes (PR 126 and DRR 46) as Factor A and nine treatments of population density of weed (i.e., 0, 2, 4, 6 and 8 plants of E. crus-galli /purple rice) as Factor B. It was observed that emergence count at 13 and 17 DAS, emergence rate index (ERI) and vigour indices (VI-I & II) at 15 DAS was the higher WF15, WF30 & WF-Th. Weed free treatments (i.e., WF30 & WF-Th) also maintained significantly higher growth, physiological parameters, yield attributes and yield, which decreased under WF15 and WT. The occurrence of various phenological stages was significantly advanced under WT treatment. However, crop-weed competition period did not influence milling and grain quality parameters except 1000-grain weight of paddy and brown rice, head rice recovery, head yield, grain breadth, which was significantly higher under weed free treatments. Although WF-Th recorded the highest amylose content but crude protein (CP) and total soluble protein (TSP) content was the highest in WT treatment. It was also found that genotypes namely; SAVA 134, PR 120 and PR 126 maintained higher ERI, VI values, growth, physiological parameters, yield attributes and yield as compared to rest of the genotypes. Genotype PR 120 took the highest, whereas PR 126 took the least number of days to reach all phenological stages. PR 120, PR 126 and SAVA 134 were found to be weed suppressive and high yielding genotypes. Although RYT 4081 was also weed suppressive but gave the least grain yield. RYT 4004, RYT 4005 and RYT 4080 were found superior w.r.t. grain and milling quality characteristics but the highest amylose and TSP content was recorded in RYT 4081. However, PR 120, PR 126 and RYT 4080 were found superior w.r.t. CP content. The correlation and path analysis studies indicated direct negative effect of LAI at 7 DAS, rice tiller count at physiological maturity, number of leaves plant-1 at 60 DAS and grain yield on weed DMA at physiological maturity, which was indirectly contributed by tiller count at 60 and 90 DAS, flag leaf area, DMA at 30 DAS, panicles m-2 and straw yield. In experiment-II, DRR 46 was recorded relatively more weed competitive than PR 126. Between E. crus-galli and purple rice, E. crus-galli was relatively more competitive at the densities of 2 and 4 plants pot-1 but at 6 and 8 plants pot-1 purple rice showed competitiveness against crop similar to E. crus-galli.