Assessing Yield and Physiological Aspects of Guar (Cyamopsis tetragonoloba L.) and Sunflower (Helianthus annuus L.) Intercropping under Different Levels of Nitrogen

IntroductionIntercropping is the cultivation of two or more crops simultaneously on the same field. The most common goal of intercropping is to produce a greater yield on a given piece of land by making use of resources that would otherwise not be utilized by a single crop. The main aims of intercropping are reduces the insect populations and plant diseases, reduces hillside erosion and minimizes labor cost on the control of weeds. Guar belongs to the legume family and drought resistant plant which is cultivated as a forage and seed crop and vegetable in warm and dry regions of Asia and Africa. This plant is a precious plant in intercropping system, because it had a development root system as a source of fertilizer and located in symbiosis with nitrogen- fixing bacteria. In fact, use guar is necessary for second crop.
Materials and MethodsIn order to investigate the physiological aspects of guar and sunflower intercropping under different levels of nitrogen a split plot experiment was conducted as based on randomized complete block design with three replications at the farm research of Agricultural Research Institute of University of Zabol (Chah nimeh), Iran in 2012-13 growing season -. Main factor was included 0, 100 and 150 kg ha-1 of nitrogen (N) (urea source) and sub factor was different planting ratio including: sole crop of sunflower, sole crop of guar, guar 75% sunflower 25%, sunflower 50% guar 50% and guar 25% sunflower 75%. Traits such as plant height, head diameter, 1000- seed weight, chlorophyll index, biological yield, seed yield, harvest index, guar LER, sunflower LER, total LER, soil nitrogen percentage and weeds dry weight were evaluated. Determination of soil nitrogen percentage carried out by using of Kjeldahl apparatus and measured leaf chlorophyll content by SPAD 502 Plus chlorophyll meter.
Results and DiscussionThe statistical analysis showed that different levels of nitrogen fertilizer, planting ratios and interactions between them had significant effect on biological yield of sunflower and guar. The highest seed yield (1633.33 kgha-1) in sowing pattern of sunflower were achieved from 75% guar 25% with consumption of 100 kgN ha-1 and in guar (4356.7 kg ha-1) from 75% guar 25% sunflower and application of 150 kgN ha-1 of . Different levels of fertilizer and planting ratios had significant effect on chlorophyll index in sunflower and guar. The highest chlorophyll index of sunflower were achieved from 100 kg ha-1 nitrogen application and %75 guar %25sunflower treatment with mean of 100 values and in guar plant this trait was 29.6 values from non application fertilizers (control) and sole crop treatment. The maximum and minimum the soil nitrogen ratio were obtained on sole crop of guar and sole crop of sunflower with mean 0.2% and 0.17%, respectively. The highest land equivalent ratio (2.73) was obtained from 75% guar 25% sunflower and the lowest of value was obtained from 25% guar 75% sunflower treatment with mean of 2.5. On account of weed control, the highest weed dry weight were obtained from sole crop of sunflower and sole crop of guar with mean 192.2 and 156.6 g m-2, respectively and the lowest of weed dry weight showed that from 75% guar 25% sunflower with mean 153.3 g m-2. Based on the results of mean comparison, the highest of LER (2.73) was obtained from 75% guar 25% sunflower treatment.
ConclusionThe highest seed yield of sunflower and guar were obtained from mixed 25% guar 75% sunflower and 75% guar 25% sunflower treatment respectively. Also weed dry weight was highest in sole crop of sunflower, but sole crop of guar and all ratios of intercropping reduced weed dry weight. The maximum of soil nitrogen was obtained from sole crop of guar and minimum value from sole crop of sunflower.