Journal of Agricultural Sciences and Natural Resources
Year:2000 | Volume:7 | Issue:3|Papers Count:8

Effects of different levels of farmyard manure and P and N fertilizers on growth and yield of seed potato, Peshendy variety, were studied. Growing season in Zanjan area was on date 1376-1377. This experiment was conducted as a split plot design in randomized complete blocks design with four replications. In this study farmyard manure was applied at three levels (0,25 and 50 ton ha-1), phosphorus at four levels (0, 80, 160 and 240 kg P2O5 ha-1), and nitrogen at four levels (0,80, 160 and 240 kg N ha-1) The results showed that levels of farmyard manure increased plant height, and also percent of medium and small size tubers per hectare. The higher levels of farmyard manure mcreased density of tuber. The large and medium size tubers in N rates is compared with treatment of 80 kg plots were higher. Generally N fertilizer rate increased the medium size of tuber in total yield of crops. The higher levels of farmyard manure, P and N reduced the amounts of dry meter in tuber.

In order to study the effects of plant density on yield, yield components and seed quality of soybean [Glycine max (L.) Merr] cultivars an expriment was conducted in 1988 at Agricultural College Experimental Station, Mazandran University, Sari. Four cultivars of soybean including Williams, Sahar, Dear and Hill with three densities: 20, 30 and 40 plants/m2 were compared in a factorial experiment based on randomized complete block design with four replications per treatment. Results showed that increasing plant density increased the height of stem and the height of first pod from ground, but other morphological characteristics such as the number of nodes in main stem, stem diameter and the number of branches were decreased. Increasing plant density, decreased number of pods and seeds per plant, seed weight and seed per pod. There was interaction between plant density and cultivars for seed yield. Dear and Williams had highest and lowest seed yield respectively. Among all cultivars, Williams and Sahar had highest (41.4%) and lowest (37.78%) percentage of protein respectively. Williams and Sahar had highest (15.17%) and lowest (11.42%) percentage of oil respectively. Totally, with increasing density, percentage of protein increased and of oil decreased.

In order to investigate the effect of early planting date on bulb production of three onion cultivars an experiment was conducted at Dezful Agricultural Education center in 1999. The design of the experiment was a split plot in the randomized complete block with 4 replications. The main plots were comprised of 5 levels of planting dates (1, 11, 21 and 31 August).In order to produce onion early seedling, they were sowing in Khoremabad Agricultural Research center. Seventy days after the seedling were transported from Khoremabad to Dezful and replanted. The seed was sowing direct as control (12 october) in Dezful region. The subplots were three onion cultivars (Ringer Grana, Primavera and Savanna Sweet). Results of the experiment indicated that yield bulb, total yield, number of bolting plants and bulb diameter were affected planting date and cultivar. Maximum and minimum of bulb diameter, total yield, leaves number and leaves weight at harvest time were obtained in first and fourth planting dates. The highest bulb weight was obtained in third and control treatments. The lowest bulb weight was achieved in first and fourth sowing dates. In the first and second sowing dates emergence of bolt was more than other sowing dates. The least plants of bolting were obtained with control treatment. Ringer Grana and Savanna Sweet cultivars exhibited the highest and lowest plant of blotting respectively. Primavera and Ringer Grana cultivars brought about the maximum and minimum bulb diameter respectively. Interactive effects of sowing date and cultivar indicated that the lowest plant of bolting of Primavera cultivar was obtained in the first sowing date. Results of this the study showed that the first and second sowing date would be better to these onion cultivars for green onion and third sowing date would be useful to produce early onion bulb in compare to control treatment. It was concluded that Primavera cultivar could be recommended early sowing time in this region.

Tampson orange (Citrus sinensis) and clementin tangerin (C.reticulata) have a matter of economical importance in citrus industry. The most common procedure of asexual propagation of citrus is inverted - T - budding which after healing the bud, can promote growth of scion. In this study four techniques of girdling, ringing, heading back and bending were used. Terminal growth of scion and number leaf were used as variables. For each species a randomized complete blocks with four treatments (growth promoting techniques) and four blocks was used. The experiment carried out in two sites of Tonekabon and Azadshar in north of Iran. The result revealed that bending had the major effect on the growth of scions. This is because using bending technique lead to accumulation of elaborate sap and growth hormones in upper part of the graft. The technique of heading back after bending had the most significant effect on growth of scion. This is because heading back eliminates auxin hormone and starts lateral bud (scion) growth. Other treatments, girdling and ringing had no considerable effects on the growth of scion.

The persent research was conducted to compare different methods of tea processing to find out fermentation and withering times. Experimental samples were collected from Lahijan research - Tea station. The old and young leaves processed separately. Two different fermentatich times as 3 and 3 1/2- h was used in this research. Different analysis were done for all samples. The amount of theaflavin and thearubiging in young leaves was more than old ones. The highest amount of theaflavin and thearubiging were observed in June samples. Values of caffeine showed irregular changes during tea processing, however young leaves had more caffeine than old ones. The amount of mineral Na, K and P did not changed during tea processing. Young leaves had more mineral than old ones. The average values of these elements were: Na(10-60), K(10000-20000), P(400-1200) microgram per gram dried tea, respectively. Florida quantity did not different between old and young leaves. Average of Florida quantity was between 90-160 microgram per gram dried tea.

Species richness and growth forms of semi-steppic vegetation type under three level of range utilizations (reference, key, and critical areas) in different land units (plain, hill, and mountain) were compared by using Whittaker plot. Group regressions between pairs of range potential showed that the slope and intercepts of regression lines for reference and key areas are not significant (P>0.05), indicating that under moderate grazing, species richness is the same as ungrazed rangelands under full protection. However, regression lines of critical and key areas and / or critical and reference areas were different (P<0.01), so under severe grazing, species richness was declined and annuals and cushion plants were invaded.

Richness, diversity, and evenness indices of species under three level of utilization (reference, key, and critical areas) in different land units ( plain, hill, and mountain) were compared by 10xl belt transect. Form richness indices, the number of all species in the sample (NO) and richness based on rarefaction method had the same behavior at different level of utilization, which were quite fitted to the real situation. But Margalef and Menhinick indices (R1,R2) did not show any sensitivity to the different levels of utilization, and were considered as improper indices. Richness based on long normal models also exaggerated the actual number of species and was not recommended. Form diversity indices, Shannon's index was preferred to the other indices which it was sensitive to the rare species at reference and key areas. So the effects of protection in terms of rare species can be evaluated by this index. Because of occurrence of rare species in reference and key areas and invaders in critical area, evenness index was higher at critical areas, so among evenness indices, Pets index (E1) was close to one, so it was more suitable than the others.