عنوان مقاله [English]
Due to the increasing population and consequently the need to supply the protein needed by the country through the production of livestock and also the importance of maintaining soil structure by creating the right crop rotation in agricultural fields, research on forage plants is inevitable. One of the methods to increase soil fertility and increase crop production is to alternate the plants of legumes in the fields. Pomegranate is also used as a source of protein in livestock and poultry feed and can be used as dry fodder, green fodder and straw for cattle and sheep. Because the organic matter in kelp forage (carbohydrates, proteins and fats) can be catabolized in livestock and used as a source of energy, kelp fodder is important in providing the minerals needed by livestock.
Materials and Methods
In order to study the effects of sowing date on seed and forage yield of four local and foreign Lathyrus sativa L. ecotype a field experiment was conducted at Shahriar, Tehran in 2021 growing season. Experimental treatments were arranged in randomized complete blocks design with factorial arrangement with three replications. In this research sowing date were in three levels (including 14th March, 6th April and 29th April) and grass pea ecotype were in four levels (Syria, Ethiopia, Eshnoye and Mashhad). For field sampling and quantitative and qualitative analysis of samples, grass pea forage crop was harvested at 50% flowering and pod stage. After determining the dry forage yield, a sample of forage of each plot was prepared to determine the quality traits. At this stage, traits such as percentage of crude protein, percentage of water-soluble carbohydrates and percentage of crude fiber using Near Infrared Reflectance Spectroscopy technology (Inframatic 8620 Percor, Germany) was measured. Simultaneously, one plant was harvested from each experimental unit and the green leaf area was calculated using a Leaf Area meter (England) in the laboratory. In order to determine the grain yield, an area of one square meter per harvest plot and measurements including grain yield and grain yield components (total number of pods, number of seeds per pod, 1000-seed weight) were performed on harvested plants. Significant differences among sowing date, ecotypes and their interaction for traits were compared by LSD test (P≤0.05) using using the SAS (9.1) package. Microsoft Office Excel (2013) and Origin Pro. 9.1 were used for figures drawing.
Results and Discussion
The results of the analysis of variance revealed ecotype, planting date and interaction between them was significant for most traits. Foreign yield was significantly affected by planting date and the highest yield was from Ethiopia ecotype in first planting. The highest percentage of organic matter, soluble sugars and crude fiber was found in the third culture, whereas protein content and leaf area were higher in the second planting date. The cultivars also showed significant difference in terms of agronomic characteristics and the maximum number of pod per plant, number of seeds per pod and seed yield was achieved from Mashhad ecotype. There is a significant interaction between cultivars and planting date, indicate that various ecotypes have different reactions at different planting dates. In additional, the results of this study showed that delay in planting due to change of temperature and day length leads to faster development, lower photosynthetic area, earlier flowering and these consequently lower yield.
Based on the findings of the current experiment, it can be concluded that the timing of sowing has a substantial impact on both the quantitative and qualitative characteristics of grass pea seed yield and forage production. The results clearly demonstrated that delaying the sowing significantly reduces grain yield. Specifically, this study identified mid-March to mid-April as the most suitable planting period for the studied ecotypes. Among the ecotypes, the Mashhad ecotype outperformed others in terms of grain yield, mainly attributed to its higher number of pods and seeds per pod. Additionally, it was observed that delayed sowing, leading to the critical flowering and seed filling stages coinciding with hot weather conditions, resulted in yield losses. These findings underscore the significance of selecting optimal sowing dates to maximize yield and avoid potential yield reductions associated with unfavorable environmental conditions during critical growth stages. On the other hand, it was found that delaying sowing from the usual planting time reduces forage quality and in the climate of the region, mid-April to early May is the best time to obtain low-volume and high-quality forage.