Effect of water deficit stress on growth and yield of three wheat (Triticum aestivum) varieties, viz. BARI Gom 25, BARI Gom 26 and Sourav was studied. Water deficit lowered the light interception at anthesis in wheat. Under water deficit condition, the highest amount of PAR interception was recorded in BARI Gom 26. The reduction of leaf area index (LAI), crop growth rate (CGR), relative growth rate (RGR) and net assimilation rate (NAR) were less in BARI Gom 26. Water deficit conditions lowered the SPAD values in all the three wheat varieties. BARI Gom 26 showed less reduction, while BARI Gom 25 reflected the highest reduction in SPAD value under water deficit condition. Under water deficit condition the maximum number of spikelets/spike, 1000-grain weight and HI were recorded in BARI Gom 26 and the minimum in BARI Gom 25. Under both control and water deficit conditions BARI Gom 26 gave the highest grain yield, while the lowest grain yield was obtained from BARI Gom 25.
Injudicious use of nitrogen fertilizer is very commonly practice in tropical and subtropical regions. SPAD (Soil-Plant Analysis Development) chlorophyll meter-based nitrogen top-dressing may reduce the risk of under or over application. Considering this, the study was conducted to measure the relative advantage of dynamic methods of nitrogen fertilization over conventional method in wheat field. For this, conventional nitrogen (CN) treatments i.e. CN60, CN90, CN120, CN150 at 60, 90, 120 and 150 kg ha-1 were compared with four chlorophyll meter-based dynamic nitrogen (DN) treatments i.e. DN80, DN90, DN120, DN100 at 80, 90, 120 and 100 kg ha-1 nitrogen. Irrespective of treatments, SPAD meter readings remained above 45 (threshold value) beyond 50 days after seeding, but plant performance varied depending on the methods and doses used in nitrogen top-dressing. Treatment CN150 performed better displaying the highest SPAD values, total dry matter production, leaf area index, crop growth rate and net assimilation rate resulting to the highest grain yield (5.10 t/ha) in wheat. The plant performance in DN120, DN100, DN90 and CN120 treatments were statistically similar to that of CN150 in respect of all most all plant characters studied. Comparing with CN treatments, DN treatments resulted in better plant growth and grain yield at the same level of nitrogen fertilizer. This is because of maintaining need-based fertilizer at early stage of wheat and application of appropriate amount of nitrogen fertilizer in each time in DN treatments compared to CN treatments. The result suggests that chlorophyll meter can be effectively used for real time nitrogen top-dressing to increase productivity of wheat.
Drought has a deleterious impact on the growth, physiology, and yield of various plants, including soybean. Seaweed extracts are rich in various bioactive compounds, including antioxidants, and can be used as biostimulants for improving yield and alleviating the adverse effect of drought stress. The purpose of this study was to evaluate the effect of soybean growth and yield with different concentrations (0.0%, 5.0%, and 10.0% v/v) of water extracts of the red seaweed Gracilaria tenuistipitata var. liui under well-watered (80% of field capacity (FC) and drought (40% of FC)) conditions. Drought stress decreased soybean grain yield by 45.58% compared to well-watered circumstances but increased the water saturation deficit by 37.87%. It also decreased leaf water, chlorophyll content, plant height, and the fresh weight of the leaf, stem, and petiole. Drought stress decreased soybean grain yield by 45.58% compared to well-watered circumstances but increased the water saturation deficit by 37.87%. It also decreased leaf water, chlorophyll content, plant height, and the fresh weight of the leaf, stem, and petiole. Under both drought and well-watered situations, foliar application of seaweed extracts dramatically improved soybean growth and production. Under drought and well-watered situations, 10.0% seaweed extract increased grain yield by 54.87% and 23.97%, respectively in comparison to untreated plants. The results of this study suggest that red seaweed extracts from Gracilaria tenuistipitata var. liui may be used as a biostimulant to improve soybean yield and drought tolerance in the presence of insufficient water. However, the actual mechanisms behind these improvements need to be further investigated in field conditions.
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