GROWTH, SOME PHYSIOLOGICAL TRAITS AND PRODUCTIVITY OF SUGAR BEET UNDER DIFFERENT IRRIGATION LEVELS AND MULCH TYPES IN NEW RECLAIMED AREA

Abstract

This work was investigated to study the combined effects of water stress levels [60%, 80%, and 100% of irrigation water requirements (IWR)] and different types of soil mulching [non-mulch, organic mulch (paddy straw and sawdust), inorganic mulch (black polyethylene film mulch (BPFM)] under drip irrigation system on growth, some physiological characteristics, yields and quality of sugar beet crop. The study was conducted at a private farm in the vicinity of Cairo-Alexandria Desert Road, Egypt (30° 14' 14.59 ̋ N latitude and 30° 46' 53.90 ̋ E longitude) during 2017/2018 and 2018/2019 seasons. The experimental design used was a split plot in a randomized complete blocks arrangement with three replications. The results revealed that most of growth, physiological and yield characteristics significantly increased by increasing irrigation levels from 60% up to 80 or 100% of irrigation water requirements (IWR) in both seasons. On the contrary, quality parameter of sugar beet decreased by increasing irrigation levels from 60% to 100% of IWR. Covering soil with inorganic mulch (black polyethylene film mulch (BPFM)) was significantly more efficient for the growth, physiological and yield parameters followed by organic cover (paddy straw and sawdust) compared to non-mulching in both seasons. The distribution of stomata density of the leaf increased as water stress level increased. There were slight differences between full the irrigation (100%) and moderate stress (80% of IWR) for stomata closure % but stomata closed under severe stress (60% of IWR). The results also showed that, all mulching types under the three water stress levels had positive effects and increased stomata area, but stomata density and its index as well as stomata closure% decreased compared with non-mulch. Finally, the highest sugar yield (ton fed -1 ) was observed under moderate stress (80% of IWR) and covering soil by BPFM.