Evaluation of yield and yield components of pumpkin (Cucrbita pepo L.) and land equivalent ratio affected as row intercropping with some field crops

Medicinal and aromatic plants are looked upon not only as a source of affordable health care products but also as a source of income. Several studies emphasized the need for cultivation of medicinal and aromatic plants in agricultural systems based on low input management. One of such causes is production of medicinal plants with oil seed with unsaturated fatty acids such as oleic and linoleic acid. Pumpkin (Cucurbita pepo L.) is an important oil seed plant belongs to family Cucurbitaceae with a prostrate stem. This seeds is used in food industry, cosmetics and health items. Active ingredients of seed are fatty acids, Vitamin E and ß-phytosterols. The major components of pumpkin oil are linoleic, oleic, palmitic and stearic acids. Seeds of pumpkin species contain 39.5-56.5% oil and 21-67.4% linoleic acid (Aroiee & Omidbaigi, 2004; Siami et al., 2003). Because of its ability to tolerate shade and to cover ground rapidly with its creeping growth habit (Aroiee & Omidbaigi, 2004), is often intercropped with other plants. This intercropping system could be effective in suppressing weed growth and increasing crop yields.
Intercropping is defined as the intensification and diversification of agricultural system in time and space dimensions. Increased food production by intercropping with more variety can to be effective in improving yield and ecosystem services and functions.
The purposes of the experiment were evaluating the yield and yield components of pumpkin in row intercropping treatments with some field crops and medicinal plants This experiment was done based on a randomized complete block design with four replications and 11 treatments at the Agricultural Research Station, Ferdowsi University of Mashhad during growing season 2014-2015. Row intercropping of pumpkin with corn (Zea mays L.), sweet corn (Zea mays convar. saccharata), sunflower (Helianthus annuus L), sesame (Sesamum indicum L), castor been (Ricinus communis L) and their monoculture were considered as treatments. Studied traits were yield components of pumpkin (such as number of fruit, fruit weight, fruit yield, number of seeds per fruit, weight of seeds per fruit and 1000- seed weight), biological and seed yield of pumpkin, corn, sweet corn, sunflower, sesame and caster been and land equivalent ratio (LER). The results showed that the effect of rows intercropping with some field crops and medicinal plants was significant on fruit number, fruit weight, fruit yield per ha, seed number per fruit, seed weight per fruit, 1000- seed weight, seed yield and biological yield of pumpkin. The highest fruit number of pumpkin was observed in monoculture with 31650 fruits.ha-1 and the lowest was intercropping with sunflower with 14386 fruit.ha-1. The maximum seed number was related to intercropping with sunflower with 333.75 seeds.fruit-1. The highest seed yield of corn, sweet corn, sunflower, sesame and castor bean was obtained in their monoculture with 772.17, 437.59, 563.69, 177.75 and 177 g.m-2, respectively. The maximum land equivalent ratio was calculated for intercropping of pumpkin+ sweet corn with 1.57. The results highlight the importance of intercropping medicinal plants and crops for improving the yield and yield components of pumpkin. The yield advantage of intercropping system occur when the component plants are in complementarily with each other, resulting in more effective use of environmental resources such as nutrients, radiation and water and yield compared with when produce as monoculture. The highest LER was computed for intercropped pumpkin with sweet corn. It seems that sweet corn had lowest competitive effects on pumpkin. On the other hand, weakness of pumpkin competitive ability in comparison with castor bean possible was due to morphology and its growth form (prostrate form). Of course it is always necessary to determine the types of interactions in intercrops in order to find out and select the best plant in intercropping with pumpkins in which the competition is the lowest, while yield components are the highest.