ABSTRACT
Due to the intensive harvest from natural habitat and increasing competition as a source of food, O. syriacum was introduced into cultivation and soon became one of the promising crops for many farmers in rural areas. The aim of the study is to investigate the effect of pine needle mulch(PN) and irrigation frequency(IF) at 5, 10 and 15 days on the yield under open field conditions. The study was conducted at the Lebanese agricultural research institute (LARI) in Lebaa station (33°32.681′ North, 35°27.088′ East, 354 m a.s.l.), south Lebanon, province of Jizzin, under open field condition for two seasons during 2016. Treatments were organized in randomized complete block design (RCBD) with three replicates. The results indicated a significant effect of mulch in both spring and fall seasons F (1, 172) = 59.34, p < .0001, η²=.24, F (1, 172) = 77.71, p < .0001, η²=.30 respectively. The two-way anova showed no significant effect of irrigation frequency on the average and total plant fresh weight (PFW) across two seasons F (2, 349) = .80, p= .4522, η²=.0038, F (2, 159) = 1.07, p= .3460, η²=.007 respectively. Very little variance of the plant fresh weight ,(0.2% – spring and 3.1 %- fall) was attributed to the interaction of mulch and irrigation frequency .In a comparison between percent weight contribution(PWC) of a different plant part, leaves formed the highest proportion (48.6%) compared to the inflorescence and stem. The fresh weight of weeds(g/ m2 ) was significantly less in plots mulched with pine needles compared to the control (F(1,66)=24.43, p<.0001, η²=.75). Applying pine needle mulch enhanced most of the yield parameters. Under calcareous clayey soil O. syriacum could be irrigated at10 or 15 days frequencies without remarkable decrease in the yield.