The results obtained showed that there was severe competition between potato and the predominant weed species Coronopus didymus, Chenopodium album, Fumaria parviflora, Melilotus indica and Spergula arvensis. Competition by other weed species was nominal. The maximum reduction in tuber yield due to weed competition was 50.5% in 1997–98 and 63.4% in 1998–99. Weed control treatments lowered the weed density and weed biomass and scaled up tuber yield in both the years, but their effect on weed species differed. Metribuzin killed all the Chenopodium album plants and gave excellent control of Coronopus didymus (94%) and effective control of other weed species. Pendimethalin inhibited the germination of Chenopodium album, gave good control of arvensis and lowered the density of other weed species. Fluchloralin completely inhibited the germination of Fumaria parviflora and gave good control of Chenopodium album and Spergula arvensis, but was least effective against other weed species. The highest yield was recorded in the weed-free treatment, which was significantly superior to all other treatments. Hand weeding + earthing up, isoproturon (1.0 kg/ha), metribuzin and pendimethalin caused an identical increase in tuber yield, which was significantly higher than the increase in the rest of the treatments. Atrazine at 0.25 kg ha –1 resulted in a higher increase than when applied at 0.5 kg ha –1 . Fluchloralin, paraquat and paddy straw mulch boosted up production, but the increase in tuber yield was not significant.
The results obtained showed that there was severe competition between wheat and the predominant weed species Phalaris minor, Avena ludoviciana and Melilotus indica. Competition by other weed species was normal. The maximum reduction in grain and straw yields due to weed competition was 34.8% and 43.7%, respectively. Weed control treatments lowered the weed population and weed biomass accumulation and boosted up the crop yield. A significant reduction in the weed population and weed dry weight was observed with increasing doses of both atrazine and metribuzin. Metribuzin at 200 g ha-1 killed all the plants of M. indica and gave excellent control of both P. minor (98%) and A. ludoviciana (89%). Atrazine at higher doses had an almost similar effect on P. minor, A. ludoviciana and M. indica with 83-87% control. Pendimethalin gave good control of P. minor and M. indica (75-83%) but poor control of A. ludoviciana (55%). The highest yield was recorded in hand weeding which was significantly superior to all other treatments. Metribuzin at 100 g ha-1 was the next best treatment, and this rate was superior to the higher doses. Pendimethalin and atrazine also brought about a marked increase in the crop yield. Higher doses of atrazine and metribuzin had a phytotoxic effect on the crop, reducing the number of productive tillers and finally lowering the crop yield, despite their excellent control of dominant weed species.
Authors:N. Jain, G.P. Singh, R. Yadav, R. Pandey, P. Ramya, M.B. Shine, V.C. Pandey, N. Rai, J. Jha and K.V. Prabhu
Under limiting water resources, root system response of genotypes to soil-water conditions with enhanced shoot biomass holds the key for development of improved genotypes. Based on the hypothesis of root biomass contribution to higher yields under limiting conditions which might be attributed to the root system plasticity of genotypes, a set of thirty-four genotypes were evaluated under three moisture regimes in a pot experiment for root system traits. Total root dry matter had a positive association with total shoot dry matter (0.35). The identified genotypes showed greater yields and higher stress tolerance index (STI) in an independent field experiment. Root dry matter positively correlated with stress tolerance index on grain yields in both the years. The total variation was partitioned into principal components and GGE biplots were studied to identify the best performing genotypes under the three environments for root dry biomass and related traits. HD2932 appeared to be the winner genotype under different regimes. These results might be helpful in identifying donors for moisture stress tolerance that can be utilized in wheat breeding programmes for accelerated development of varieties with improved root systems.
Authors:Ashish Pandey, Anoop Kelkar, R. Singhal, Chetan Baghra, Amrit Prakash, Mohd. Afzal and J. Panakkal
Pyrohydrolysis is a fast, reliable and convenient method for the decomposition of solid refractory samples. Thoria based mixed
oxide nuclear fuels requires more than 1,200 °C reaction temperature to lose its structural integrity so as to release the
halides. In the present paper, we report WO3 accelerated pyrohydrolytic extraction technique for the separation of F− and Cl− from thoria based fuels along with the feasibility of using MoO3 and V2O5. The mechanism of extraction has been investigated in detail using X-ray diffraction and recovery studies. ThO2 along with its halides undergo high temperature solid state reaction with WO3 forming Th(WO4)2 and releasing the halides for their subsequent hydrolysis. The quantification was carried out by ion chromatography with
suppressed ion conductivity detection. The average recoveries of the spiked samples for F− and Cl− were 93–99%. The method was successfully applied for simultaneous determination of F− and Cl− in thorium based nuclear fuel samples at 950 °C.