1. KAUTIR (Kerala Agricultural University Theses Information and Retrieval)
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Item Integrated weed management in blackgram [Vigna mungo (L.) Hepper] with pre-mix herbicides.(Department of Agronomy, College of Agriculture, Vellayani, 2025-05-05) Ameena, MAn investigation entitled ‘Integrated weed management in blackgram [Vigna mungo (L.) Hepper] with pre-mix herbicides’ was conducted at College of Agriculture, Vellayani during 2022-2024. The major objective was to formulate an integrated weed management strategy using pre-mix herbicides for black gram intercropped in coconut garden. The field experiment was conducted at the Instructional Farm, Vellayani during the summer season from February to April 2024 in a coconut garden with palms above 40 years of age. The experiment was laid out in randomized block design with nine treatments replicated thrice. The weed management practices tested were: T1- pre emergence (PE) pendimethalin + imazethapyr (premix 1) 800 g ha-1; T2 - T1 followed by (fb) hand weeding (HW) at 30 days after sowing (DAS); T3- post emergence (PoE) propaquizafop + imazethapyr (premix 2) 125 g ha-1; T4- T3 fb HW at 40 DAS; T5- PE pendimethalin 1kg ha-1 fb HW at 30 DAS; T6- PE pendimethalin 1kg ha-1fb PoE imazethapyr 50g ha-1; T7- PE pendimethalin 1kg ha-1 fb PoE propaquizafop 100g ha- 1; T8- HW at 15 and 30 DAS; T9- weedy check. The blackgram variety DBGV-5 treated with Bradyrhizobium inoculant BMBS 47 was dibbled in the interspaces of coconut and managed as per the KAU Package of Practices. Pre emergence herbicide was applied on the next day of sowing and post emergence applied at 15 DAS. Symptoms of phytotoxicity were observed in crop as mild stunting in plots sprayed with premix combination, pendimethalin + imazethapyr which persisted upto 10 days after herbicide application. The results of the study revealed that weed management practices had no significant influence on the growth attributes of blackgram. However, the yield and yield attributes were significantly influenced by the weed management practices. Higher pods per plant was recorded in T4 (36.00) and was comparable with T7 (35.83) while weedy check recorded the lowest number of pods (14.24). Hundred seed weight was recorded higher in T2 (5.33 g) and was on par with T4 (5.17 g) and T1 (5.13 g). The highest seed yield per plant was recorded in T4 (9.60 g) followed by T7 (9.23g), T6 (8.3g) and T5 (8.23g). Post emergence application of premix 2 fb HW at 40 DAS resulted in higher seed yield per ha (1793 kg) and was comparable with T7 (1731 kg). Higher haulm yield per ha was recorded in T5 (3658 kg) and was comparable with T4 (3616 kg), T6 (3581 kg) and T7 (3485 kg). The study observed that absence of weeding led to the highest yield reduction in blackgram, with a weed index of 54.44 per cent while yield reduction was lower in T4 (2.45%) and on par with T7 (5.35%). The predominant weed flora in the experimental field was grasses. However, more diversity was observed in the flora of broad leaf weeds. Pre emergence application of premix 1 fb HW at 30 DAS resulted in significantly lower weed density and weed dry weight and higher weed control efficiency at all stages of observation and was comparable with T7, T4 and T6. At 30 and 45 DAS, T1, T2, T5, T6 and T7 resulted in lower relative biomass of grasses that was comparable with T4 and the highest relative biomass of grasses was recorded in weedy check (85.92 %). Treatments involving both pre- and post-emergence herbicide applications (T7 and T6) resulted in higher dehydrogenase enzyme activity at 30 DAS, while their combination with hand weeding (T4, T5) showed increased activity at 45 DAS. Weed management practices significantly influenced nutrient uptake, with T7 and T1 exhibiting higher N, P and K uptake. The integration of premix herbicides with hand weeding and use of pre and post-emergence herbicides, significantly reduced N, P, and K removal by weeds throughout the growth period. The BC ratio varied significantly among the weed management practices with the highest in T4 (1.95), followed by T7 (1.94), with the lowest ratios in hand weeding twice (1.05) and weedy check (0.82). Weed management practices significantly influenced the population of Bradyrhizobium, fungi and actinomycetes in rhizospheric soil at 30 DAS with T2 showing higher count and on par with T1. However, no significant differences were noted in the population of phosphorus solubilising bacteria across all time points. The in vitro sensitivity test of Bradyrhizobium to premix 1 and 2 at concentrations of 800 to 2000 ppm and 175 to 325 ppm respectively showed positive growth with no inhibition zones around the sterile disc containing herbicide mixture placed on a lawn of Bradyrhizobium in the medium. The study identified application of propaquizafop + imazethapyr 125 g ha-1 at 15 DAS fb HW at 40 DAS; and application of pendimethalin 1kg ha-1 on the next day of sowing fb propaquizafop 100g ha-1 at 15 DAS as the most effective weed management strategies in terms of yield, weed control efficiency and gross return in blackgram. Considering economics, application of propaquizafop + imazethapyr at 15 DAS fb HW at 40 DAS could be adjudged as the most effective integrated weed management strategy for achieving higher seed yield in blackgram intercropped in coconut garden.Item Investigation on allelopathic influence and control of purple nuts edge(Department of Agronomy, College of Agriculture, Vellayani, 1999) Ameena, M; Sansamma GeorgeLab and field experiments were conducted at the Instructional farm, College of Agriculture, Vellayani to study the allelopathic influence of Purple nutsedge (Cyperus rotund us L) on important field crops; to investigate the effectiveness of systemic herbicides for control of nutsedge and also to assess the effect of chemical weed control on growth and yield of subsequent field crops. In Ex. no. I, allelopathic influence of purple nutsedge on important field crops like rice, ragi, cowpea, green gram, bitter gourd and bhindi were studied. The treatments comprised of aqueous extracts and blended extracts of fresh and dry plant parts of nutsedge. The results revealed that aqueous extracts of nutsedge inhibited germination of rice, ragi, bitter gourd and bhindi while it had some stimulatory effect on germination of cowpea and green gram. The early growth characters of the field crops were found suppressed by the aqueous extract treatment while the blended extract showed no effect. In general, the dry plant parts showed greater effect than the fresh material. Under Ex.no.Il, field studies were made to investigate the effectiveness of systemic herbicides viz. Glyphosate and 2,4-D for control of nutsedge. The treatments included different doses of the herbicides with and without adjuvants and Glyphosate combined with sublethal dose of 2,4-D. The results revealed that lowest dose of the herbicides were sufficient for complete kill of the purple nutsedge plants in the experimental area and there was no regrowth upto 6 weeks. There was significant reduction in viability of tubers collected one month after herbicide application, but the tubers tested 45 days after spraying showed an increase in germinability over the record on 30th day. Tubers from treatments involving Glyphosate with sublethal dose of 2,4-D recorded the lowest sprouting percentage indicating the possibility for weed control for a longer period. In Ex. no. In, the persistence of the herbicides in soil were monitored and it was observed that early growth of cucumber sown on the same day of herbicide application was affected while that sown on soils collected 10 days after spraying recorded growth characters comparable to that of control. From Ex.no.IV, it could be inferred that chemical weed control did not show any deleterious effect on growth and yield characteristics of ragi and cucumber sown 15 days after the treatments. Application of 2,4-D for nutsedge control was found superior to other treatments in terms of net income and B:C ratio and the lower unit cost of the chemical was precisely the reason for its superiority.Item Integrated management of purple nutsedge(Department of Agronomy, College of Horticulture, Vellayani, 2003) Ameena, M; Geetha Kumari, V LAn investigation entitled "Integrated management of purple nutsedge (Cyperus rotundus L.)" was conducted during 1999-2002 at College of Agriculture, Vellayani, Thiruvananthapuram. It comprised of one pot study, two field experiments and three laboratory experiments. Pot experiment was conducted to study the biology of purple nutsedge under various seasons and stage of tuberisation. Field experiments were conducted to evolve an integrated management strategy for purple nutsedge control in cropped area and a long-term control strategy in non- cropped area. Laboratory experiments were conducted to assess the allelopathic influence of purple nutsedge root exudates on early growth of crop seeds and nutsedge extracts on weed seeds. An attempt has been made to identify the allelochemicals present in tubers of nutsedge by employing HPLC (High Performance Liquid Chromatography) technique. In pot study, the growth and development of purple nutsedge was observed for a period of one year. Results of the study indicated that chain tuber took more time for sprouting compared to shoot tubers or bulb. The time required to sprout varied with seasons in the case of chain tuber and August and March planted tubers took lesser time for sprouting. March and May planting tecorded more tuber production compared to August and November planting. August planted tubers recorded very early tuberisation and November and May planted tubers took more or less double the time for tuberisation compared to August planted tubers. Field studies in cropped area indicated that the growth characters of okra were significantly influenced by the weed management practices. Flowering was early by about 7-10 days in mulched plots under both stale seed bed and soil exposure treatments compared to weedy check plots. Stale seed bed coupled with mulching registered maximum leaf area index during both the years. All the weed control treatments except where cowpea was raised as smother crop resulted in significantly more fruits per plant and fruit yield per hectare. Maximum productivity of 5.24 t ha" was realised by stale seed bed with eucalyptus mulched plots which was 171.5 and 11 per cent more than weedy check and weed free plots respectively. The treatments had no significant influence on quality attributes of okra like vitamin C, keeping 'quality, protein and fibre content of fruits. Regarding soil fertility status, minimum depletion of nutrients occurred in completely weed free and mulched plots. Stale seed bed with polythene mulching or pre and post emergent glyphosate application were identified as the best nutsedge control measure in cropped area. Post emergent glyphosate application after stale seed bed has found to show spectacular inhibitory effect on nutsedge multiplication and spread and this treatment recorded the highest percentage reduction values for nutsedge control. Lowest rate of regeneration was recorded by this treatment with lower viability of tubers. The most economical treatment was stale seed bed with glyphosate application integrated with eucalyptus mulching and it recorded the highest net returns (Rs.18,2701-) and B:C ratio (2.01). In non-cropped area. results of two seasons study indicated that the effective stage for glyphosate spraying was identified as before tuber initiation. The degree of inhibition exerted by glyphosate on regeneration of nutsedge tubers was higher thanthat of 2.4-0. Among the summer season treatments stale seed bed with irrigation followed by glyphosate application was the best in achieving higher level of control. In allelopathic studies. nutsedge root exudates collected at sprouting stage inhibited the germination and growth of all the crop seeds tested vi : .. rice. co wpea. sesamum. okra and brinjal. Also the nutsedge extracts collected at different stages inhibited the growth and development of Gomphrena de cumbe nse and Syne drell a nodij7ora. The allelochemicals present in tubers of purple nutsedge was identified by High Performance Liquid Chromatography (HPLC) and it indicated the presence of p-hydroxy benzoic acid, p-coumaric acid, m- coumaric acid, vanillic acid and gentisic acid.