Physiological growth and gas exchange response of saffron (Crocus sativus L.) to irrigation water salinity, manure application and planting method

• Very high salt sensitivity of saffron is remediated by in-furrow planting.
• The in-furrow planting reduce salinity effects on growth parameters of saffron.
• Higher cow manure remediated the salt sensitivity of photosynthesis in saffron.
• The in-furrow planting method increased corm growth even under high salinity levels.

The objective of the present study is to investigate the effects of irrigation water salinity, cow manure levels and different planting methods on saffron growth rate and gas exchange. A split-split plot arrangement was conducted in randomized complete block design with irrigation water salinity levels (0.45 (fresh water, S1), 1.0 (S2), 2.0 (S3), and 3.0 (S4) dS m−1) as the main plot, cow manure levels (30 (F1) and 60 (F2) Mg ha−1) as the subplot and planting method (basin (P1) and in-furrow (P2)) as the sub-subplot in three replications. Results showed that initial amount of planted corms were degraded by using saline water (EC higher than 2.0 dS m−1) in the basin planting method and under F1 and F2 cow manure levels in consecutive growing seasons; however, we observed an acceptable increase in corm growth in high salinity levels (S3 and S4) under the in-furrow planting method. Assessment of the ratio of corm DW to the leaf DM showed that corms propagation were higher in the first year; however, in the second year higher weight proportions of dry matter were allocated to the leaves. Maximum saffron LAI and crop growth rate (CGR) decreased significantly as about 26% by using the highest water salinity level and these parameters increased as 37 and 61%, respectively by using the in-furrow planting method. Higher cow manure (F2) also increased LAI and CGR by 16 and 13%, respectively. Results of gas exchange parameters showed that photosynthesis rate (An) decreased as about 32% in the highest water salinity level. Higher manure application increased the An as about 18%. Also, An increased significantly by 29% under the in-furrow planting method compared with that in the basin. An was 17% higher in the second year than that in the first year and the conversion rate of photosynthetic production to shoot dry weight for developed saffron increased by about 47% due to leaf area index increase. High salt sensitivity of saffron could be remediated by using the in-furrow planting method and higher cow manure application rate.