Selda Ors

Evaluation of water use and yield responses of drip-irrigated sugar beet with different irrigation techniques

Effective water use should be investigated in terms of sustainable production strategy in arid and semi-arid regions. A 2 yr field study was conducted in order to investigate the effects of full root-zone wetting (FI) and partial root-zone drying (PRD) irrigation techniques with 4 and 8-d (I2) irrigation intervals and three different irrigation levels (W1, W2, W3) adjusted according to Class A pan evaporation on root, leaf, and sugar yields and irrigation water use efficiency (IWUE) of sugar beet (Beta vulgaris L.) Three different plant-pan coefficients (0.70, 0.60, and 0.50) were used for adjusting the three different irrigation levels. The irrigation techniques and levels affected yields significantly. Seasonal meanly irrigation quantities were 280.4 mm in FI treatments and 162.4 mm in PRD treatments. While mean root yield of 33.80 t ha-1 is obtained in FI treatments, it was 26.43 t ha-1 in PRD treatments. Similarly, mean white sugar yield (WSY) for FI treatments (5 t ha-1) was higher than PRD treatments (3.81 t ha-1). There were significant polynomial relationships between irrigation quantities and root yield or WSY in both FI and PRD treatment. PRD technique increased by 34.9% IWUE compared to FI. Although the highest root yield was determined in FI-I1W1 sub treatment as 37.57 t ha-1, the highest IWUE was determined in PRD-I1W3 sub treatment as 173.9 kg ha-1 mm-1 since it has the lowest irrigation water amount as 140.6 mm. However, among PRD treatments for more root yield and for more white sugar yield, I1W1 and I1W2 sub treatments were the best.

Seasonal induced changes in spinach rhizosphere microbial community structure with varying salinity and drought

Salinity is a common problem under irrigated agriculture, especially in low rainfall and high evaporative demand areas of southwestern United States and other semi-arid regions around the world. However, studies on salinity effects on soil microbial communities are relatively few while the effects of irrigation-induced salinity on soil chemical and physical properties and plant growth are well documented. In this study, we examined the effects of salinity, temperature, and temporal variability on soil and rhizosphere microbial communities in sand tanks irrigated with prepared solutions designed to simulate saline wastewater. Three sets of experiments with spinach (Spinacia oleracea L., cv. Racoon) were conducted under saline water during different time periods (early winter, late spring, and early summer). Bacterial 16S V4 rDNA region was amplified utilizing fusion primers designed against the surrounding conserved regions using MiSeq® Illumina sequencing platform. Across the two sample types, bacteria were relatively dominant among three phyla-the Proteobacteria, Cyanobacteria, and Bacteroidetes-accounted for 77.1% of taxa detected in the rhizosphere, while Proteobacteria, Bacteroidetes, and Actinobacteria accounted for 55.1% of taxa detected in soil. The results were analyzed using UniFrac coupled with principal coordinate analysis (PCoA) to compare diversity, abundance, community structure, and specific bacterial groups in soil and rhizosphere samples. Permutational analysis of variance (PERMANOVA) analysis showed that soil temperature (P=0.001), rhizosphere temperature (P=0.001), rhizosphere salinity (P=0.032), and evapotranspiration (P=0.002) significantly affected beta diversity of soil and rhizosphere microbial communities. Furthermore, salinity had marginal effects (P=0.078) on soil beta diversity. However, temporal variability differentially affected rhizosphere microbial communities irrigated with saline wastewater. Therefore, microbial communities in soils impacted by saline irrigation water respond differently to irrigation water quality and season of application due to temporal effects associated with temperature.

Responses to the Irrigation Water Amount of Spinach Supplemented with Organic Amendment in Greenhouse Conditions

The effect of organic amendment applications on some agrophysiological properties of pot-grown spinach was investigated under drought stress. The I1, I2, I3, and I4 irrigation treatments received water amounts up to 100, 80, 60, and 40 percent of evaporation from a reduced pan, respectively. A liquid organic amendment was applied to spinach seeds as seed treatment at the ratios of 0.1 percent (H1) and 0.2 percent (H3). Furthermore, in the H2 and H4 treatments the amendment was foliar applied to spinach seedlings at the ratios of 0.1 percent and 0.2 percent in addition to the seed treatments, respectively. Organic amendment treatments positively affected root and leaf growth. The plants responded to water stress by lower growth. Leaf relative water content, membrane permeability, chlorophyll reading, and stomatal conductance values also indicated significant changes. These results support the view that organic amendment application increased growth. However, it could not provide a significant contribution for growth under water stress.

Changes in gas exchange capacity and selected physiological properties of squash seedlings (Cucurbita pepo L.) under well-watered and drought stress conditions

ABSTRACT Water use efficiency (WUE) is considered as an important component of adaptation to drought stress. This study was conducted to determine the effect of drought stress on gas exchange parameters and selected physiological properties, and also its relations with WUE in summer squash seedlings (Cucurbita pepo L.). Plants were grown in pots under different irrigation levels (D0: 100%, D1: 67% and D2: 33% of the water required to reach the field capacity) in controlled greenhouse. The results show that drought treatments significantly decreased the leaf chlorophyll reading values (LCRV), leaf relative water content (LRWC), stomatal conductance (gs), photosynthetic rate (PN), transpiration rate (Tr), fresh weight (FW) and dry weight (DW) of squash seedlings by 7, 42, 69, 62, 62 63 and 82%, respectively, in D2 treatment compared to D0. However, electrolyte leakage (EL) values increased 72% with severe drought treatments (D2). The highest WUE was obtained by D0 treatment as 0.26 g mm−1. The relationship between PN and WUE is the strongest one among all leaf gas exchange parameters. Together with Tr, the linear relation with WUE was considerably higher compared to other measured parameters.

Nitrik Oksit Uygulamalarının Bitkilerde Abiyotik Stres Şartlarına Toleransı Arttırmadaki Etkileri

Gunumuzde bitkisel uretimini sinirlandiran cevresel stres faktorleri nedeniyle, yetistiricilikte bitkinin normal urun potansiyeline ulasmasini saglayacak uygun alanlarin bulunmasi oldukca zorlasmistir. Tarimsal uretimin azalmasinda cok buyuk oranda abiyotik stres, daha dusuk oranlarda ise diger stres faktorleri etkilidir. Abiyotik stres faktorleri olarak, kuraklik, tuzluluk, yuksek ve dusuk sicaklik, sel, radyasyon, agir metaller, oksidatif stres, ruzgâr, besin maddesi eksikligi gibi faktorler sayilabilir ve bu stres kaynaklari bitki gelisimini, kaliteyi ve verimliligi olumsuz yonde etkilemektedir. Gaz halindeki farkli bilesikler arasinda, nitrik oksitin (NO) bitkilere disaridan uygulanmasi son yillarda daha fazla onem kazanmistir. NO tohum cimlenmesi ve fide buyumesinin iyilestirilmesi gibi bitkilerde duzenleyici rollerinin yani sira, metal toksisitesi, sicaklik, kuraklik ve tuzluluk gibi farkli abiyotik streslere karsi da koruyucu bir rol oynamaktadir. Bu makalede bitkilerin kuraklik, tuzluluk, yuksek ve dusuk sicaklik ile agir metaller gibi abiyotik stres kosullarinda NO uygulamalarinin etkileri tartisilmistir.